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.
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
- Photovoltaic solar panels: responsible for collecting solar radiation and converting it into electricity.
- Roof mounting structure.
- Batteries: responsible for storing the converted electrical energy, allowing its use at any time, even during the night.
- Charge Controller: device responsible for managing battery charging.
- 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.
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