Image: Bilanol – Shutterstock.

Everything about solar panels on roofs: how they work, their advantages, their installations and their alternatives.

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

Rooftop solar panels: what are they and how do they work?

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

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

To get energy from a solar panel, just put it under sunlight.

Solar energy 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 which adapts the energy generated by the panels to be used in the house and which manages the energy of the system with the electrical network.
  • Connection box: system of safety devices against electrical overloads and on / off switch.
  • Supports: 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 set installed and in operation is called a photovoltaic system.

Since it generates energy with sunlight, the solar panel on the roof will not produce energy at night and will do so at a lower wattage on rainy or cloudy days, usually on less bright 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 home at night or during times of low panel production.
  • Connected to the network: These are the systems connected to the commercial electricity grid, which exchange the surplus generated during the day for the energy consumed from the grid at night.

Most of the systems installed are network type, due to their lower cost and easier maintenance.

Image: Slavun – Shutterstock.

System connected to the grid (On-Grid)

An “On-Grid” photovoltaic system operates connected to the commercial electricity grid. All the energy produced during the day by the panel and which is not consumed immediately is returned to the public network. The investor is responsible for this task.

During sunny hours, the panel generates power 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 quantity of energy produced is greater than that requested, the inverter injects the surplus into the electrical network of your distributor.

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

Solar panel on the roof: 7 advantages

Of all the renewable energy sources authorized for distributed generation, solar is the most widespread in the world.

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

1. Durability.

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

The loss of efficiency in converting light to energy is minimal and the major manufacturers guarantee 80% of the production 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 initially generated.

The photovoltaic inverter, which is the other fundamental element of the system, has a minimum useful life of 15 years. With proper maintenance, it can be stretched out a bit more.

2. Minimal maintenance.

Although the system operates long hours every day, photovoltaic systems require very little maintenance.

The main thing, which you can do yourself, is to clean the plates.

But this is only in the event that they are very dirty, because they have a non-stick film that prevents the accumulation of dirt. In the case of dust, rainwater wins out.

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

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

3. Weather resistance.

These systems are manufactured with the necessary protection against physical damage. Photovoltaic panels are tough, they can withstand even the impact of large hailstorms. Everything to ensure that they work for their long life.

4. Increase in the value of the property.

Another great benefit for those who install solar power in their homes is the value it adds to their home.

A house that generates its own energy should be worth more than a house that doesn’t.

Therefore, if you decide to rent or sell your house after installing a PV system, you can sell it for a higher price.

5. Price of electricity.

Having a photovoltaic system in your home ensures that you are not afraid of the electric bill.

With a photovoltaic system, you will be protected against price increases.

6. Quick return on investment.

Installing a solar power system is an investment. And the payback period for investments in solar energy is very interesting.

While this will depend on the cost of your installation and the price of electricity where you live, I can assure you that you will recoup the investment before you reach the end of the useful life of your tiles, so you will benefit from a few years. 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 the 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 used on the grid and you will only have to pay the minimum price.

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 where distribution grids did not reach.

The great examples of the use of off-grid photovoltaic systems are the artificial satellites (telecommunications, meteorological …) which orbit our planet, and all are electrically powered by solar panels, which are one of the components of the photovoltaic system. implemented. in 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 city of Americus, Georgia in 1955.

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

It was then that the use of photovoltaic solar energy made a qualitative leap, and since the end of the 90s, 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 photovoltaic systems.

Components of an off-grid system

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

These systems are ideal for homes that want to live independently, generating and consuming their own electricity, or for detached homes that do not have the option of connecting to the commercial power grid.