What is photovoltaic energy?

Photovoltaic energy is the electrical current produced by light in solar cells in the solar module. The energy of the light is transformed into electricity in the photovoltaic cells. The electricity can then be used in electrical equipment, fed into the electricity network for use by others or stored on a battery.

Photovoltaic energy is generated by sunlight in solar modules that are mostly made of silicon solar cells in the solar module. The light travels as light particles which are called photons. Each photon when hitting the cell can displace one electron, thereby transferring its energy to the electron. In practice, this energy transferred to the electrons is reflected in the electrical voltage of the solar module and as an electric current. The modules are coupled sequentially and in parallel to produce the total power required for the solar photovoltaic system.

Solar power in Finland

The amount of electric energy produced per year by the photovoltaic system (kWh) can be reasonably predicted based on the solar rotation, system position and module orientation using the current and past weather and solar radiation data from the meteorological institutes.

In Finland, the annual amount of radiation varies between 790 and 980 kWh / m2, depending on the location. This can be achieved with a solar photovoltaic system of about 700-1000 kWh per installed kilowatt. The differences between regions are mainly due to cloudiness and, furthermore, the production per north decreases as the sunlight has to penetrate the thicker layer of the atmosphere. In the dark winter months, solar electricity is often unavailable. Instead, the spring snowdrift reflects a lot of light and thus increases solar energy output. Variations during the years are also significant. It may well be up to 20% variation in the production of successive years.

A photovoltaic system

Naps photovoltaic system is optimized for the needed use. System optimization takes into account local weather conditions, shading, module installation, and the need for the item's electricity and the timing of its use.

Photovoltaic systems contain solar modules, mounting brackets, electric cables, and in use either inverters for connecting the system to the grid or charge controller and batteries. Off-grid battery systems can also be supplemented by inverters for conventional 230 V electrical devices. The module is installed in a non-shaded sunny position and is directed generally to the south side, often in the same direction as the ceiling.

Shadows reduce photovoltaic production. Shadows that substantially affect the production of solar electricity are minimized during the design phase of the system mainly through the placement of modules and, if necessary, by taking care of the removal of the trees. The fouling of modules affects the production of photovoltaic electricity in Finland in general very little. Most of the rain keeps the modules clean enough.

Naps Aurinkosähkön Asiantuntija

Optimizing the production of solar modules At Naps' systems, we use chain-specific optimization or module-specific optimization. Module-specific optimization in Finnish conditions is seldom economically viable in the long run, because in module-specific optimization, the number of separate electrical devices required for the system increases and thus increases the need for maintenance. However, module-specific optimization is justified in situations where individual modules of the same chain are placed in different lighting environments, such as a different mounting angle on different roofs of the roof, or where a module is almost always partially shaded.

Read more about sizing the solar power system