Category: Solar Panels (Page 2 of 2)

Rv solar panels

December 27, 2022 / / 0 Comments

If you want to be more self-sufficient in your travels, you can purchase a solar kit for caravan, with which you can charge the batteries and generate your own electricity. Everything you need to know before installing your solar panels on your caravan, camper or motorhome is explained in the following post. We help you so that campering your caravan with solar panels does not become a complicated task.

 

Useful tips before installing solar panels on a caravan

First of all we must assess whether it is worth installing panels or not. If you are one of those who do a few kilometers a day and end up sleeping in a campsite where you can connect to the mains, you probably do not need this type of installation. If, on the other hand, you spend several days in the same location and do not usually spend the night in campsites, keep reading because you are interested in this post…

IMPORTANT considerations before equipping our caravan with photovoltaic solar energy are:

  • See the space we have because the biggest limitation of these facilities is the usable space on the roof.
  • Calculate the power we need according to our consumption.
  • Types of trips and duration of the trip.

Necessary elements in a solar installation for caravans.

 

2.1- Solar panels

Function: The main function of the solar panel is to obtain electrical energy from the solar radiation during the day that they capture thanks to their silicon cells., which is distributed through the electric cable to the charge regulator, which will be in charge of storing it in the battery. They are installed on the roof, usually glued and without protruding from the dimensions of the roof according to Spanish regulations. In a camper van the solar panel is usually used as a charging aid.

  • How many solar panels do I need for a camper van?

The number of panels that we will need for our installation will depend on the electronic devices that we want to connect. We will have to consult the watts (in the back label of the device), the hours that they will be working and then we will be able to make the calculation.

  • Calculation of the power I need in my solar panels

The most important thing is to know the consumption that we are going to have to be able to size our installation correctly. Let’s see an example of calculation:

  • The yield of a plate is approximately 60-70%, therefore, a 100W solar panel will deliver a maximum of 60W.
  • The installation position of a solar panel on the roof of a van is not optimal. A solar panel, to work at maximum performance, should be placed at an angle of 45º in winter or 15º in summer. For mixed use, it is normally installed at 30º in fixed domestic installations.
  • The location and time of year are factors to be taken into account.

The current intensity that a panel will be able to supply is determined by the following formula :

Intensity = Power/Voltage * Efficiency

If we have a 100W solar panel and an efficiency of 70%, the formula would be as follows:

100W/12V * 0.7 = 5.83Ah

This means that the solar panel, in full sunlight, can generate at most 5.83 Amps per hour.

If we assume that our daily consumption is 50 Amps, let’s see what solar panel we would need.

We are also going to suppose that in summer we take advantage of a total of 7 hours of sun per day, while in winter, because there are less hours of sun, we only take advantage of 3 hours per day on average.

Well, if we have a 100W solar panel for example, we would obtain the following daily energy:

In summer: 5.83A/h x 7 hours = 40.81 Amps per day.

In winter: 5.83A/h*3 hours = 17.49 Amperes per day.

In no case do we reach 50 Amperes of daily consumption. In addition, we are not taking into account other losses that exist (such as the loss of the charge regulator), the loss in the wiring and without counting the days when there is no sun… With 100W of panel, the solar panel is simply going to be a support for the battery to discharge more slowly.

The more panels we can install, or more capacity (Wp), the more energy self-sufficiency we will achieve.

Below we leave you some solar kits for caravans as an example, so you can get an idea of the configuration. They are kits that already include all the materials ready to install: solar panels, batteries, inverters, regulators and necessary wiring.

  • What solar panel is better: Monocrystalline or Polycrystalline?

Depending on the climate, one type of panel or the other is recommended. Monocrystalline panels tend to be used more in cloudy climates and polycrystalline panels in places where the sun shines more directly and where they are more resistant to high temperatures. On the other hand, monocrystalline plates are usually more powerful for the same number of cells (same surface area).

The differences are not very noticeable, so it is better to choose those that are better value for money.

  • Maintenance of the solar panels in a motor home

For the good functioning of our installation it will be necessary to keep the solar panels clean. The fact of installing the solar panel in a flat position will make the dirt accumulate more easily.

  • Autonomy solar panels in a motorhome

When installing the solar panels in our caravan what we obtain is to recharge the batteries without the vehicle is in march and without being connected to an electrical network, which is perfect to lengthen the life of the batteries and to avoid that they remain without load.

 

2.2- Batteries for motorhomes.

Function: The batteries are in charge of storing the energy during the hours of light captured by the solar panels to be able to have it later at night or in moments of low luminosity. When choosing it we will have to take into account the percentage of discharge.

  • What type of battery is best for my caravan?

The battery is one of the most important components to take into account in any photovoltaic installation. The caravans normally already have batteries but if what we want is to connect different devices and to make use when we are stopped, the own ones that the caravan takes would not serve us.

The original batteries of the car are not designed for such use.and in addition to using them, there would be a high risk that the battery would be discharged so much that the van would not even start…

We would have to add auxiliary batteries. Although there are different types of batteries, in Atersa Shop we recommend the AGM or Gel batteries because they are more economic, they admit deep discharge cycles and they are completely safe because they are sealed and they do not need maintenance. They can be installed in any position, although it is not advisable to install them in inverted position.

With the AGM batteries and GEL batteries (as the rest of lead/acid batteries) we will have to bear in mind that the discharges are carried out to 50% more or less. Which means that although we have the battery charged to 100% it is only going to be discharged up to the half.

  • What battery capacity should I choose?

The capacity of the battery is measured in Ah (ampere hours). To choose the suitable battery we will have to consider the total sum of amperes that we are going to need daily according to the consumptions. We will always value this data a little above in case in a future we want to extend.

To calculate the capacity of the battery that we need in our installation

We give you some advices to calculate the ideal size of battery;

The voltage by defect in an electrical installation of camper van is of 12V. Bearing in mind that the capacity of the battery is measured in Ah (ampere hours). Next we will calculate what is going to be our consumption with the following formula.

THE FORMULA IS -> Energy (Wh)/ Voltage (V) = Ah (amp hours)

IN THE SAME WAY -> Ah (ampere hours) * Voltage (V) = Energy (Wh)

As we have indicated, AGM/Gel batteries (as any lead acid battery) should not be discharged below 50%. Therefore, the amount of Ah (ampere hours) should be more than double the result obtained.

Example of consumption in Ah per day :

The sum results in a total consumption of 47.68 Ah. Taking into account this data we would choose a battery of 100Ah/day (the double) as minimum and thus we solve the problem of the discharges to 50% (the battery must not be discharged more than 50% of its capacity). If this consumption is done during 2 days then the capacity of the battery would increase to 200 Ah (2 batteries of 100ah connected in parallel or one of 200Ah). To be able to connect them in parallel in this case, we will always have to make sure that the two have the same voltage and to have wiring as similar as possible.

If you have enough space, a higher capacity battery (150Ah or more) would be ideal, as this will mean that you will have more autonomy.

Each trip is different, so we recommend that you make the appropriate calculations depending on the type and duration of your trips. If you are one of those who move around and do not spend the night in campsites, you will need more autonomy and therefore more battery capacity.

2.3- Charge regulator

Function: What the charge regulator does is precisely to “regulate” the energy supplied by the solar panels until it reaches the batteries. The regulator manages the energy of the solar panels, the necessary one for the batteries to work and will even know at all times when the battery is discharging and when it will have to start charging it. It is installed between the solar panels and the battery.

  • Difference between PWM and MPPT charge controller:

PWM charge controllers are much cheaper than MPPTs but if what we want is to install high power solar panels, or maximize the performance of our panels, we would have to use MPPTs. Discover the differences between these two types of regulators.

Regulators are measured in Amps. To know the type of regulator we need, we must first know the peak watts (Wp) that our panel installation will provide.

If for example we have 150Wp panels and we work with 12V voltage, we will be talking about 12.50 Amps. In this case the PWM charge regulator would have to be of the same amperes or higher amperage.

In a MPPT regulator you can use larger panels or connect several panels in series increasing the voltage of the panel field but the result is similar. A 30A 12V regulator will allow the installation of panels up to 360Wp or several panels in series not exceeding the same power figure. It is advisable to follow the manufacturer’s instructions in order not to exceed the maximum power or voltage allowed by the MPPT regulator.

2.4- Current inverter (optional if we wish to have alternating current).

Function: The inverter is connected to the auxiliary battery and is in charge of transforming the 12v provided by the battery (direct current) to 230v (alternating current, which is what we usually have at home). It is the one that is going to allow you to connect different electronic devices.

If we are only going to charge the cell phone and a light bulb we will not need to have an inverter in our caravan, it would be enough with the solar panel and the battery. But if we need to charge more devices such as a laptop, a hairdryer or a coffee maker then the inverter will be essential.

  • What type of inverter is best for a caravan?

There are two types of inverters. From pure wave and modified wave. We advise to use pure sine wave inverters for caravans, they are more expensive but it is the most similar to the connection to the network that we have in our house and allows us to connect any appliance.

We observe the watt hours (Wh) consumed by each appliance and according to this we choose the power of the inverter.

 

Is it necessary to homologate the solar installation on a caravan?

The approval of a solar installation on a caravan in Spain is currently mandatory if the dimensions of the vehicle are modified. Exceeding the dimensions of the vehicle without approval may result in the immobilization of the vehicle, or it may not pass the Itv.

The installation of a solar panel in a flat position on the vehicle is not considered a homologable modification (as long as it does not protrude from the roof of the vehicle). In any case, it is advisable to get more detailed information at any station.

 

Installing the solar kit on your caravan

In Atersa Shop you can buy all the necessary products for the installation separately but we have configured solar kits for caravans thinking about your needs. Buying the set will be more economical.

To install your solar kit follow these basic instructions;

  • Attach the solar panel with silicone to the roof and run the wires inside.
  • Connect the regulator to the battery and then the panels to the regulator.
  • Use a fuse between the regulator/inverter and the battery and another fuse between the regulator/inverter and the battery to avoid overloads.
  • Use the right wiring. Take into account the length and thickness.

 

Solar panel roof: all you need to know

August 5, 2022 / / 0 Comments

All about rooftop solar panels: how they work, benefits, installations and alternatives.

A photovoltaic system, which has the solar panel as one of its main players, can reduce your electricity bill by up to 95%.

Solar panels roof: What are they and how do they work?

A solar panel is a set of solar panels, or photovoltaic modules, that generate energy by direct conversion of sunlight.

Each of these panels is composed of dozens of photovoltaic cells. These cells generate energy directly by converting sunlight.

To obtain energy from a solar panel, simply place it in direct sunlight.

Solar power kit.

To power your home with solar energy, it is not enough to have a solar panel, you will also need other equipment.

In a solar energy kit we find:

  • Solar inverter: equipment that adapts the energy generated by the panels to be used in the house and that manages the energy of the system with the electrical grid.
  • Junction box: system of safety devices against electrical overloads and on/off switch.
  • Brackets: metal structure used to fix the panel on the roof of the house.
  • Wiring: set of connectors and cables for the electrical connection of the system.

The installed and operating assembly is called a photovoltaic system.

As it generates energy with sunlight, the solar panel on the roof will not produce energy during the night, and it will produce less power on rainy or cloudy days, in general on less luminous days.

We have two alternatives to solve this problem:

  • Off-grid installation: from the English “off grid”. These are systems that use batteries to store excess energy during the day, which will power your house during the night or in periods of low production of the panels.
  • Grid-connected: These are systems connected to the commercial power grid, which exchange the surplus generated during the day for the energy consumed from the grid during the night.

Most of the systems installed are of the grid-connected type, due to their lower cost and simpler maintenance.

Image: Slavun – Shutterstock

Grid-connected system (On-Grid)

An on-grid photovoltaic system operates connected to the commercial power grid. All the energy generated during the day by the panel and not immediately consumed is fed into the utility grid. The inverter is responsible for this task.

During sunshine hours, the panel generates energy and sends it to the inverter. The inverter converts this energy (from direct current to alternating current) and sends it to the devices that consume it. If the amount of power generated is greater than the amount demanded, the inverter injects the surplus into your distributor’s power grid.

During the night or at times of low system production, power from the commercial grid is used.

Rooftop solar: 7 advantages

Among all the renewable energy sources allowed for distributed generation, solar is the most widespread around the world.

In addition to being the most widely used, photovoltaic systems also offer several advantages that make them the best choice.

1. Durability.

Even exposed to the elements on the roof, a solar panel has a standard lifetime of at least 25 years.

The loss of efficiency in the conversion of light into energy is minimal and the main manufacturers guarantee 80% of the generation at the end of this period. A module, up to 25 years of life, will generate at least 80% of the amount of energy it generated at the beginning.

The PV inverter, which is the other key part of the system, has a minimum life of 15 years. With proper maintenance it can be extended a little longer.

2. Minimal maintenance.

Despite the fact that the system works for many hours every day, PV systems require very little maintenance.

The main one, which you can do yourself, is the cleaning of the plates.

But this is only in case they are very dirty, as they have a non-stick film that prevents the accumulation of dirt. In the case of dust, rainwater will wash it away.

In case of excess dirt or bird droppings, cleaning is simple and only requires a jet of water and a soft bristle broom.

We should also maintain the electrical system, but much less frequently. Once a year is sufficient to ensure the optimization of the system generation.

3. Weather resistance.

These systems are manufactured with the necessary protection against physical damage. The photovoltaic panels are resistant, they can withstand even the impact of large hail balls. Everything to ensure that they work during their long life.

4. Increased property value.

Another great advantage for those who install solar home energy is the value it adds to your home.

A home that generates its own power should be worth more than one that does not.

Therefore, if you decide to rent or sell your house after installing a photovoltaic system, you will be able to sell it at a higher price.

5. Price of electricity.

Having a photovoltaic system on your house ensures that you won’t have any surprises on your electricity bill.

With a photovoltaic system, you will be protected against rate hikes.

6. Fast return on investment.

Installing a solar energy system is an investment. And the payback period for solar energy is very attractive.

Although it will depend on the cost of your installation and the price of electricity where you live, I can assure you that you will amortize the investment before reaching the end of the useful life of the panels on your roof, so you will enjoy some years of free electricity.

7. Reduction of the electricity bill.

And, of course, this return on investment is only possible thanks to the greatest advantage of these systems: savings of up to 95% on your electricity bill.

A grid-connected photovoltaic system (On-Grid) can be designed to generate all the energy consumed in a house. Thus, you stop paying for the energy you have used from the grid and will only have to pay the minimum fee.

Off-grid photovoltaic system.

In the early days of solar PV, between the 1950s and 1970s, off-grid PV systems were the only type that existed because the goal was to bring electricity to places where distribution grids did not reach.

The great examples of the use of off-grid photovoltaic systems are artificial satellites (telecommunications, meteorological…) orbiting our planet, and all of them are electrically powered by solar panels, which are one of the components of the photovoltaic system implemented on the satellite.

Photovoltaic solar panels were mainly used in telecommunications. One of the first documented uses of solar panels was to power a “rural telephone”, installed in the American town of Americus (Georgia) in 1955.

The concept of on-grid and off-grid PV emerged only after the use of inverter technology to directly connect solar PV panels to the grid, without the power going through a battery bank; which would eliminate one of the most expensive (and least durable) components of a stand-alone PV system (off-grid PV system), which is the battery.

It was then that the use of solar PV took a qualitative leap, and since the late 1990s, mainly with subsidies, the mass production of the main components (modules, inverters, charge controllers, batteries) began, followed by new techniques and components for the integration of PV systems.

Components of an Off-Grid system

  1. Photovoltaic solar panels: responsible for collecting solar radiation and converting it into electricity.
  2. Roof mounting structure.
  3. Batteries: responsible for storing the converted electrical energy, allowing its use at any time, even during the night.
  4. Charge Controller: device responsible for managing battery charging.
  5. Solar inverter (stand-alone): component responsible for transforming the direct current generated by the solar panels and stored in the batteries into alternating current, allowing its use by the different electrical appliances in the house.

These systems are ideal for houses that want to live autonomously, generating and consuming their own electricity, or for isolated houses that do not have the possibility of connection to the commercial power grid.

How many solar panels do I need? Calculate it yourself

June 23, 2022 / / 0 Comments

The number of solar panels that any photovoltaic installation will need will depend on the energy consumption, which can vary between low, medium and high.

How to calculate solar panels?

Calculating the number of solar panels is one of the most important procedures in the implementation of a photovoltaic installation. This step is technically known as sizing and is carried out taking into account the amount of energy consumed (measured in kWh) during a year.

The following table shows how the number of solar panels required can be calculated according to consumption. Specifically, an electricity bill is used to find out the annual consumption in kWh, quantify the number of solar panels that will be needed and forecast their installation cost.

Solar panels calculation

Type of consumption Electricity bill month Consumption kWh/year No. of solar panels Price of installation
Under Less than 50 2,400 kWh/year Less than 3 panels Around € 2,500
Low – medium 50 – 100 € 3,600 kWh/year 3 – 6 panels From 3.300 €
Medium 100 – 150 € 6,000 kWh/year 6 – 9 panels Starting at 4.800 €
Medium – high 150 – 200 € 8,400 kWh/year 9 – 12 panels From 6.300 €
High 200 – 250 € 10,800 kWh/year 12 – 14 panels From 7.500 €
Very high More than 250 € 12,001 kWh/year More than 14 panels From 9.100 €

Approximate figures

In this way, and following this table, any person can know how many solar panels he/she will need to be self-sufficient. All you need to do is

  1. Have access to the last electricity bill you received.
  2. Place yourself in the table, in the price range that corresponds to your case.
  3. Take a good look at the other consumptions that you have near your cell, because the final calculation may vary.

Solar panels calculator

Another option, also free and online to identify the number of solar panels that will be needed, is to use a solar panels calculator. This is a very useful tool, which is made available to any user by the installation companies, and which allows you to quantify the number of solar panels and the price of their installation.

These solar panel calculators work in the same way as a form. Through a question-answer system, they are able to identify the user’s energy needs. In such a way that, at the end of the questionnaire, they can issue an indicative budget.

In some cases, this final document also provides an estimate of savings and a financed installation price. In fact, this is the case of the online solar panel calculator that BlueSolarPanels has set up.

Through it, a user, whether the owner of a house, a commercial premise or belonging to a community of neighbors, can get a general idea of the number of solar panels that will be needed.

Although a multitude of similar tools can be found online, most solar panel calculators usually ask the same questions to the user, as these are necessary to provide any kind of indicative installation budget. Some of the most common ones are:

  • Asking for the type of building where the panels are going to be.
  • Asking for the address or zip code
  • Knowing the energy consumption: through the electricity bill or the CUPS number.
  • Inquire about the type of roof on the property
  • Need some personal information such as email or telephone, to detail the information provided.

Why use a solar panels calculator before installing? Before installing it is highly recommended to use a solar panels calculator. This tool allows users to get an insight into photovoltaic energy and learn first-hand about key aspects to make the decision to switch to solar self-consumption.

How many solar panels do I need for a house?

To illustrate how to calculate the number of solar panels based on energy consumption, let’s see how many solar panels would be necessary for a house. Specifically, for 2 types of houses:

  1. The first dwelling is a rural house, of sporadic use, which has a low energy consumption.
  2. The second dwelling is a residential house, which has a high energy consumption.

We are going to observe, comparing both cases, how the number of solar panels needed increases based on a higher or lower use of household appliances.

Number of solar panels as a function of plugged-in items

Elements plugged into the grid Number of solar panels you will need
  • Rural house of sporadic use with low consumption
  • One refrigerator
  • One TV
  • Lighting (8 bulbs)
  • Washing machine
 You will need 4 solar panels
  • Residential house with high consumption
  • Refrigerator
  • Washing machine
  • Microwave
  • 2 televisions
  • 1 computer
  • Toaster
  • Radio
  • Iron
  • 6 fans
  • 6 lamps
  • 12 light bulbs
  • The motor of the purifier for a removable swimming pool
  • Daily cell phone charging
 12 solar panels

Also, apart from energy consumption, other factors can be used to calculate how many solar panels a house needs. Mainly, there are 2:

  • The surface area of the house (m2)
  • The number of people living in the house

How many solar panels do I need for a house of a specific m2?

How many solar panels do I need for a 200 m2 house?

The number of solar panels needed for a house of 200 m2 is between 8 and 12 solar panels. This is a large property, which will need several panels to supply the lighting and other domestic energy it uses.

How many solar panels does a 100 m2 house need?

Typically, the number of solar panels being installed on houses with a surface area of 100 m2 is between 4 and 8.

How much does a solar panel produce per m2?

A 460 W solar panel can produce about 350 kWh per m2 per year.

However, the energy production of the solar panel per m2 will depend on the power, the material, the size and the other characteristics that make up the price of solar panels.

6 key aspects of the price of solar panels

Power
The higher the power, the higher the price. It is measured in peak power (Wp).

Cells
Transform the sun’s rays into electricity. They can change the size of the panel.

Material
Monocrystalline is more efficient and expensive. Polycrystalline is less efficient and less expensive.

Aesthetics
is determined by the color, such as All Black. And also by the flexibility of the panel.

Size
There are solar panels of 0.5 cm and can exceed 2 meters. They are measured in length x width x height.

Brand
There are brands that are more expensive because of their prestige, but new, more economical ones are emerging.

Number of solar panels according to the number of cohabitants

Finally, another element that could be taken into account to calculate how many solar panels a house needs is to analyze the number of cohabitants. Normally, a house with a large family tends to need more energy than a house with a married couple. Even if both have the same square meters.

Calculation of solar panels according to the number of cohabitants

Number of cohabitants Number of solar panels Price of the installation
2 persons 3 solar panels 3.300 €
6 persons 9 – 12 solar panels 6.300 €
4 persons 6 persons 9.100 €

Also, and within the sizing process, users are often interested in the number of solar panels needed to be able to consume a number of kilowatt hours per year, or the number of solar panels needed for their installation to have a certain power (Wp).

Here are the most frequently asked questions on this subject.

How many solar panels do I need according to the Wp power?

How many solar panels do I need to generate 5 kw?

With a good orientation and inclination, you would need 8 solar panels of 460 Wp to generate 5,000 kWh/year of consumption.

However, if you want to have a photovoltaic installation that reaches 5 Wp, you would need 11 solar panels of 460 Wp.

How many solar panels do I need for 4000w?

Users who are interested in having a solar panel installation to consume 4000 kWh/year will need 6 solar panels of 460 Wp.

But if they want to have an output of 4000 Wp they will need 9 solar panels.

How many solar panels do I need for 3000w?

With a good orientation and inclination, 4 solar panels of 460 Wp would be needed to generate 3,000 kWh/year.

However, in the case of a self-consumption installation with a power of 3000 Wp, 7 solar panels will be necessary.

How many solar panels do I need for 20,000w?

35 460 Wp solar panels are needed to generate 20,000 kWh/year.

And if you want to have an installation of solar panels that can reach 20000 Wp, 43 solar panels would be needed.

How many solar panels do I need for 2000w?

With a good orientation and inclination, 3 solar panels of 460 Wp would be needed to generate 2000 kWh/year of consumption.

On the other hand, to have an installation that reaches 2000 Wp, 5 solar panels would be needed.

How many solar panels do I need for 1500w?

To consume 1500 kWh/year, 2 solar panels are needed. But to have an installation of 1500 Wp, 4 solar panels of 460 Wp would be needed.

How many solar panels do I need to generate 1 kw?

To have a self-consumption installation and to be able to consume 1 kWh/year, 2 solar panels are needed.

However, if what is needed is to have an installation that reaches 1 Wp, 3 solar panels would have to be installed.

Step by step calculation of solar panels

To determine the number of solar panels needed for a self-consumption installation, installation companies use a special formula: the solar panel calculation. This is a complex formula, which should only be carried out by qualified technicians. This is the only way to ensure, as they say in the industry, the correct sizing of the photovoltaic system.

In order to carry out the calculation of solar panels, it is necessary to have a series of technical information:

Data for the calculation of solar panels

User data

  • Annual consumption in kWh. You can see it in the electricity bill and multiply it by 12.
  • The annual consumption in the example will be 8,400 kWh/year.
  • Hours of light per year. It will be necessary to multiply the daily hours of light of the province by the days of the month during a year.
  • In the example it will be 2,190 hours (6 hours x 30 days x 12 months).

Technical data of the panel

  • Solar panel power. It can be found in the technical data sheet of the product. They are between 300 and 500 Wp.
  • In the example the panel potential will be 460 Wp.
  • Production loss of the panel. This percentage can be found in the data sheet of each panel.
  • In the example it will be 1.15%.

Calculation formula for solar panels

1.- Calculation of daily consumption

  • Annual consumption kWh / Light hours h
  • Example: 8.400 kwh/year / 2.190 h = 3,8 kw

2.- Introduction of the production loss factor

  • Daily consumption kW x Production loss factor %.
  • Example: 3,8 kW x 1,15 % = 4,4 kw

3.- Obtaining the number of plates

  • Daily production / plate power x 1.000 (to convert to Kilowatts)
  • Example: 4,4 / 460, x 1.000 = 9,7
  • Answer: 10 solar panels are needed for a consumption of 8,400 kWh.

The calculation of solar panels changes according to the province. In order to make this calculation of solar panels more precise, installers take into account more technical factors such as the production of the panel according to the geographical area. This means that the number of solar panels needed varies from one province to another, even if the building has the same energy consumption.

BBVA-solar-panels-int-2-sustainability-energy-light-plates

What are solar panels, how do they work and what is their future?

June 7, 2022 / / 0 Comments

The sun can provide enough energy to power the entire planet. But you can’t do it directly. Solar panels are the intermediary that makes sunlight serve us as energy. Its design is simple, very efficient and allows self-consumption, which promotes sustainability . In the near future, the panels will generate electricity even at night.

A single hour of sun would be enough to supply the energy demands of humanity for a whole year. The statement is not exaggerated and explains better than any graph would, the importance of the human being being able, through different processes, to convert into electrical energy what the sun gives away. Solar energy as an alternative for the future of humanity.

The use of renewable energies to be self-sufficient, and thus save on our electricity and gas bills, is an upward trend that also takes care of the environment . The arrival of European funds represents an unprecedented opportunity to promote photovoltaic self-consumption in Spain, at a business level and especially in the residential world. The ‘Roadmap’ for self-consumption, published by the Government in December last year, seeks to promote the installation of solar panels in more than 40,000 homes. In this sense, BBVA provides its customers with the possibility of receiving advice and help in the management and processing of subsidies for self-consumption, storage and air conditioning, as well as requesting financing solutions.

But how is this almost miraculous process carried out? Through two simple installations: solar photovoltaic panel installations (better known as plates or solar panels) and thermal installations. Both are different and are made up of also different teams.

To fully understand what these photovoltaic panels are, it is best to go back a few years (even a century). “We are talking about a 21st century energy, although in reality it was discovered at the end of the 19th century. And it was during the 20th century when it began to develop”, explains Carlos Montoya, head of the Solar Department of the Institute for Energy Diversification and Saving (IDAE) , attached to the Ministry for Ecological Transformation and the Demographic Challenge, to BBVA. “In 1920, Albert Einstein already discovered the photovoltaic effect and for this he took the Nobel a year later.”

How does this effect work? It is a physical phenomenon that consists of the emission of photoelectrons by a material when it receives light energy. “This phenomenon makes it possible for us to exploit solar energy to produce electricity,” says Íñigo Ramírez González, a photovoltaic solar energy researcher at the Polytechnic University of Madrid.

Knowing this concept, now it is important to explain what a photovoltaic solar installation is . It is a rectangular structure with a basic unit of transformation that is the solar cell and that measures approximately 10 square centimeters. A panel joins several of these cells on a plate, which are covered with a plastic called EVA. It is a type of polyethylene made up of various compounds (ethylene and vinyl acetate) that is one of the great allies of the photovoltaic industry. Because? Because this polymer can withstand extreme conditions and temperatures and also allows light to pass through, but not ultraviolet rays, which are more damaging to the skin.

A solar panel is made up of about 60 cells , although this size varies depending on the manufacturer, and its thickness is around four centimeters. Íñigo Ramírez points out: “The energy they produce is direct current and we use alternating current in our homes, so the panels also have an essential element that is the inverter, capable of transforming the current so that we can use that energy.”

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Silicon since 1954

The first photovoltaic cells were developed in 1954. Daryl Chapin, electronic engineer; Gerald Pearson, a physicist, and Calvin Fuller, a chemist, the three researchers from the American Bell Laboratories, presented their great discovery to the world: it was the first cell that captured energy from the sun and with it a transistor could be made to work. That cell had a particularity: it was made of silicon. “This is precisely the fundamental material that absorbs sunlight and through which that light is transformed into electricity. It is a semiconductor with very good characteristics for manufacturing solar cells and it is very abundant on earth, as well as being cheap”, explains Ramírez.

SOLAR ENERGY

This is how a solar power plant works to generate energy

Solar installations take advantage of radiation to transform it into thermal or electrical energy. There are two types: thermoelectric plants heat a fluid to obtain water vapor and move the turbine that generates electricity, while photovoltaic parks control the silicon reaction that converts light into electrons.

Photovoltaics is a source of energy that has become more and more important over the years. Before the 1970s, its use was merely aerospace , but from then on, it came down to Earth. It is modular, that is, its efficiency does not depend on its size, so it is scalable and can be located in the home.

However, in countries like Spain its use is still eminently industrial. “The more than 10,000 megawatts (MW) of photovoltaic power installed in the country mainly supply companies and industrial buildings ”, explains the head of the IDAE Solar Department. We still have a long way to go to reach China, the world’s largest power in photovoltaic energy.

Solar panels: make the most of the sun and save energy

Returning to these panels, another of the most frequently asked questions is whether the farms (as these facilities are known) of solar panels move with the sun. There are two answers, some panels are installed on fixed inclined structures and others are installations with a tracker, that is, they have an intelligent motor that moves them so that they are at their most efficient point every day of the year.

Regarding the power that standard size panels can generate, it is calculated that a 2 x 1 meter module – between 60 and 72 cells – provides approximately between 300 and 445 Wp (peak watts) for each hour of sunshine.

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Photovoltaic future

The future of the panels passes through the present of scientific research. At Stanford University (USA) they have just developed a facility capable of generating electricity when the sun has gone down. Solar panels ‘in reverse’ take advantage of the energy that the panels radiate after many hours of sun. This phenomenon is known as ‘radiative cooling’ and occurs when a body loses heat after high temperatures. Recovering that heat that is given off, even at night, could be a solution for the panels to perform better.

Solar farms in elevated installations on agricultural fields or greenhouses to optimize space and, at the same time, keep the panels cooled by the humidity released by the plantations; solar trackers to track the sun more economically and efficiently, or solar cells made with organic components that transform the windows of industrial or residential buildings into semi-transparent solar panels are some of the solutions underway.

If you are interested, we offer you these solutions designed for you.

Do solar panels work on cloudy days?

April 14, 2022 / / 0 Comments

In these winter days, when the hours of sunshine are shorter and clouds cover the sky, one of the most frequent questions from our customers is how can our solar panels be affected on cloudy days with hardly any sun?

In this article we will review how our solar panels work, the elements that influence the performance on cloudy days and we will see how we can improve our photovoltaic self-consumption on days without sun.

Do solar panels work on cloudy days?

The answer would be, yes, our solar panels will still work on cloudy days. It is common to think the opposite, since the initial intuition leads us to associate photovoltaic energy with the sun’s heat, and it is important to know that this is not the case, but that our panels are powered by sunlight and not by its heat.

While clouds can limit direct radiation from the sun, they do not totally prevent light from reaching our solar panels. The energy absorbed by our solar panels comes from both visible light and a range of different wavelengths, many of which can penetrate the cloud cover without a problem. This is known as diffuse radiation, and occurs when the sun’s rays do not strike our solar panels directly, having to pass through clouds or fog.

So as long as there is light in the environment, the panels will continue to generate energy, whether the day is cloudy or sunny.

However, the effect of very cloudy or completely overcast days, we will see in the amount of energy that our photovoltaic modules are able to produce, that is, in their performance.

What elements influence the performance of solar panels on cloudy days?

Photovoltaic panels are composed of solar cells that collect sunlight and convert it into direct current (DC). This current is sent to the inverter to be converted into alternating current (AC) which is the electrical energy that we usually consume in most homes. The efficiency of a solar panel would therefore be the percentage of sunlight that the panel collects and converts into the actual electricity we consume. The greater the amount of energy produced, the higher the efficiency of our photovoltaic modules.

There are different factors that can influence this performance. In the case of cloudy or overcast days, two in particular stand out: the technology of the panels and the type or thickness of the clouds.

In terms of technology, the cells that make up our solar panels are the ones that convert the sunlight that strikes them into electricity (photoelectric effect). Larger cells will be more effective in capturing sunlight than smaller ones. Similarly, there are other technologies that can be more efficient than others, such as bifacial panels, which can collect more solar radiation throughout the day.

Beyond the photovoltaic modules, the performance is also influenced by the other components of the installation, such as the inverter, the wiring and the battery, if available.

As for clouds, not all types affect performance in the same way. In this sense, low, dense clouds with different degrees of opacity (nimbostratus and stratus or haze) are the ones that will limit the performance of our solar panels the most.

How much is the performance of our solar panels affected on cloudy days?

To see how cloudy days affect the performance of our photovoltaic modules, we have used the monitoring of a residential installation in Madrid and an industrial installation in the south to compare the electricity production on a cloudy day and a sunny day, both in winter and summer. We first sought to compare two consecutive days of sun and clouds, and then compared the cloudiest day of the month with the sunniest.

For the residential self-consumption installation, the production on January 19, 2020, with clear skies, was 10.79 kWh. The next day, the skies were overcast and production dropped to 2.08 kWh. This means that the output on the cloudy day is 80.73% lower than on the sunny day.

If we compare the cloudiest day of that month with the sunniest day, the yield drops to 96.34%.

Production of residential installation on a clear day in winter.
Production of residential installation on a cloudy winter day.

If we place ourselves in the month of July 2020, the 7th was a sunny day, being able to reach a photovoltaic production of 16.36 kWh. On the following cloudy day, the production dropped to 9.54 kWh. This represents a yield loss of 41.69 %. A reduction that amounts to 44.6 % if we compare the cloudiest day with the sunniest day in August 2020.

Production of residential installation on a clear summer day.
Residential installation production on a cloudy summer day.

For the industrial self-consumption industrial self-consumptionThe production on January 19, 2021, a sunny day, amounted to 33.70 kWh. Meanwhile, on the 20th of the same month, the skies were cloudy and production fell to 9.47 kWh. This represents a 71.90% loss in performance. And if we compare the cloudiest day with the sunniest day of that month, the percentage loss rises to 87.79%.

Production of industrial installation on a clear day in winter.
Industrial facility production on a cloudy winter day.

Finally, if we look at July 2020, the sun shone on the 11th to reach a production of 74.22 kWh. The next day, the skies were overcast again and production dropped to 52.68 kWh. This makes a yield loss of 29.02 %, which would increase to 35.12 % if we compare the most cloudy day with the clearest day.

Production of industrial installation on a clear summer day.
Production of industrial installation on a cloudy summer day.

Thus, depending on the type of cloud cover we encounter, the yield of our solar panels can vary between 5 % and 70 % of their capacity on a cloudless day. The loss will be greater on winter days, due to the fewer hours of sunlight available compared to summer.

Can cloudy days help improve the performance of our solar panels?

In the winter months, if we add to a cloudy day that the days are shorter and therefore, there is not much possibility of balancing the loss of performance with the time that our panels are exposed to sunlight, clearly the answer would be no.

However, if we are in summer with temperatures exceeding 25°C during the day, the output of solar panels can be affected by temperature (as we saw in another blog post). Some types of clouds, especially white fluffy clouds, can help to reduce the temperature of the solar panels and thus contribute to improve their performance.

In addition to reducing the temperature, these types of clouds act as a mirror by reflecting the light that bounces off the earth’s surface or, in this case, also on our panels. In this way, they receive direct sunlight and the light reflected by these clouds.

However, we must understand this improvement as relative, because although with white and fluffy clouds we can reach higher peaks of energy production, sunny days are still the days with the highest total production throughout the day.

How to improve the efficiency of solar panels on cloudy days?

Although technologies are advancing rapidly and there are already prototypes of cells that improve the normal performance on cloudy days, the best way we currently have to take advantage of our photovoltaic installation on days when the production of the panels drops considerably, is to get an energy storage system or solar batteries. In this way, you can take advantage of the surplus production on sunny days to use them at night or on days when the performance falls due to external causes to the installation, such as overcast skies.

Another possibility, if you have a self-consumption installation connected to the grid, is to dump the surplus energy, asking your utility company to compensate you for the surplus in your electricity bill.

In case you have an isolated photovoltaic installation, it can be useful, in addition to the batteries, a backup generator, especially when we chain several very cloudy days.

Photovoltaic self-consumption systems are built to withstand the elements, both physically and in their ability to produce energy, under any normal weather conditions, whether rain, wind, hail or clouds.

If you are thinking of switching to photovoltaic self-consumption, be clear that most of the inclement weather will not have a great impact on your clean energy installation, with which in addition to saving you will be contributing to reduce, among other things, CO2 emissions.

And if you need advice or a no obligation quote, contact us without obligation. We will make a preliminary study in which we take into account the average solar radiation in your area so that your installation adapts both to your consumption needs throughout the year and to the production possibilities of the area where the installation will be carried out.

How to clean your solar panels?

How to clean solar panels in 2023

February 7, 2022 / / 0 Comments

How to clean your solar panels?

Run away from dirty solar panels! We teach you the keys to maintaining and cleaning your facility

 Reading this article will take you less than 9 minutes

How to clean your solar panels?

Solar panels must be exposed to sunlight to produce energy, therefore, they are also exposed to inclement weather. However, unless you live somewhere with a high level of pollution, dust, sand or snow, your photovoltaic solar panels do not need to be cleaned frequently .

In most cases, the rain is more than enough to keep the solar panels clean. Although it may be a good idea to “water” the photovoltaic panels occasionally if you live in beach areas or areas with high pollution. Below, you will find the answers to the main questions that the owners of self-consumption facilities have about the maintenance of solar panels and the cleaning of photovoltaic modules .

Maintenance of solar panels

Photovoltaic panels have a high durability and resistance, therefore, it is not necessary to pay much attention to the maintenance of solar panels in residential solar self -consumption installations.

With the exception of photovoltaic panel installations with trackers, an installation has no moving parts, which means that the risk of breakdowns and problems decreases significantly. In order to be able to observe any live variation of your installation and anticipate immediately in the event of an incident, installers recommend placing performance monitoring devices .

In most cases, the solar panels are cleaned directly with the rain. However, in areas with a lot of wind, high pollution, dust or dirt, production can decrease by up to 15% throughout the useful life of the solar panel installation. This percentage may increase or decrease depending on three factors:

  1. The type of dirt , since a bird droppings will not be the same as a little dust.
  2. The type of installation , if it has optimizers or not, if it has been installed in series or in parallel .
  3. The inclination of the panels , for example, some panels with more inclination better receive rainwater and this natural cleaning, and vice versa.

To mitigate this effect, it is necessary to clean the solar panels.

  • In the case of solar panels on sloping roofs , it is advisable to hire a professional maintenance and cleaning service . Many local installers offer these services or recommend professional solar panel maintenance companies they trust.
  • If the panels are easily accessible , you only need warm water and low pressure.

Products to clean solar panels

The most important aspect to take into account if you are cleaning your solar panels is that you should not scratch or damage the glass , since doing so will reduce the energy production of that panel to a greater or lesser extent .

The best way to clean solar panels is:

  • With warm water and carefully, in the same way that you would when cleaning your windows. Try to use only water , and if you use a product, make sure it is one that does not leave residue, such as dishwasher soap.
  • To remove dirty water or excess lime , you can use any utensil that does not press or scratch the panels. For example, a scraper or glass cleaner.
IMPORTANT! CLEANING MUST BE DONE FIRST THING IN THE MORNING

Clean the panels before they begin to shine, to avoid temperature contrasts that can cause glass breakage.

And remember, avoid damaging or scratching the glass of the plates at all costs . If you live near a highway with a high frequency of trucks or close to an airport , oily stains may appear on your license plates. It is easily and simply removed using a little isopropyl alcohol and a rag. However, the use of “strong” cleaning products is not recommended , as they can damage or even scratch the glass.

How often do you have to clean the solar panels?

At least once a year , at most two. As we mentioned, this will depend on the area in which you live. If you live in an area that is regularly affected by dirt caused by sand, trees or birds, the panels should be cleaned more frequently.

 

Is it worth paying for a photovoltaic solar panel cleaning service?

Just like going to a car wash, there are professional options that will take care of cleaning and maintaining your solar panels for self-consumption for you. Some solar panel installers include cleaning options in their maintenance fee. They could also budget them separately or recommend a company specialized in this work.

If your installation is on your deck or roof and it is difficult to access , it is advisable that you hire the services of a professional for security reasons. You’ll only have to do it once a year or every two years, so it won’t be a big outlay and you’ll avoid unnecessary risks . Cleaning services won’t do a significantly different or better job than you can (they’ll simply make your solar panels stop being dirty), but they are equipped to clean and maintain the cells in a safe way.

In the event that you have the photovoltaic panels installed on the ground, it is not worth hiring the services of a cleaning professional, since you can clean the solar panels yourself with a hose.

Cleaning of photovoltaic modules

Special cases

HAIL

The photovoltaic cells that make up the solar panels are made of silicon. The panels, in turn, are covered by glass, and although this material is quite resistant, a weather phenomenon that is too aggressive could cause serious damage to your installation. For this reason, we always recommend including the panels in your home insurance. This should not lead to an increase in the fee, although it depends on your insurance.

In any case, the probability that the hail impact affects the solar panels is minimal . In the event that something went wrong, there are guarantees that cover these incidents.

SNOW

In areas where snowfall occurs periodically, it is only necessary that your solar panels have an inclination greater than 15º so that the snow does not accumulate . In addition, the melting process is usually fast and favors the cleaning of the panels as if it were a natural maintenance.

Generally, it is not necessary to remove snow from solar panels as it will move on its own. Most solar panel installations are tilted at a certain angle, and the snow will naturally move by gravity as it melts.

If you notice snow lingering on the panels, you can purchase a roof rake specifically for solar panels. The use of this type of tools allows you to safely remove snow without damaging or scratching them and consequently reducing their energy production. For this reason, it is important not to use a standard broom, shovel or any other non-specialized tool to remove snow from solar panels.

If you need any information or want to know how much your installation of solar panels would cost, do not hesitate to contact us , the experts will be happy to answer all your questions and offer you a free fully personalized study.

Solar Panel Warranties

Manufacturers offer different guarantees on their solar panels to provide support and coverage in the event of an unlikely incident , such as a breakdown due to hail or falling branches or other objects.

  • Production guarantee: refers to the fact that the performance of the nominal power of the solar panels will not drop below a certain level throughout the useful life of the installation. This guarantee lasts up to 25 years. A large part of the manufacturers use the 80th percentile as a guarantee, that is, at 25 years they deliver 80% of the power of the solar panels in year one.
  • Additional guarantee: directly related to the previous one, it is the same as the production guarantee, but in a much shorter period of time. Some manufacturers guarantee panel performance will not drop below 90% of year one power rating for the first 10 years.
  • Labor guarantee: although it has nothing to do with the operation of the panels, it protects the client’s roof and the materials on the work of the installers; wiring, conduits, electrical protections, sealing of roof anchors, etc.

At Blue Solar Panel we can advise you from the first moment so that you don’t have to worry about anything, we will help you choose the best solar panels and we will advise you on what type of maintenance you should do depending on where you live.

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