PVGIS - Calculator

We advise you not to modify this color code.

For a quick calculation we advise you to check calculated horizon

The solar radiation and photovoltaic production will change if there are local hills or mountains that block sunlight during certain periods of the day. PVGIS can calculate the effect of this by using data on ground elevation with a resolution of 3 arc-seconds (approximately 90 meters).

This calculation does not take into account shadows from very close objects such as houses or trees. In this case, you can upload your own information about the horizon by checking the "Download horizon file" box in CSV or JSON format.

We recommend keeping the default database determined by PVGIS.

PPVGIS offers four different databases on solar radiation with hourly resolution. Currently, there are three satellite-based databases:

PVGIS-SARAH2 (0.05º x 0.05º): Produced by CM SAF to replace SARAH-1 (PVGIS-SARAH). It covers Europe, Africa, most of Asia, and some parts of South America. Time range: 2005-2020.

VGIS-SARAH (0.05º x 0.05º): Produced using the CM SAF algorithm. Similar coverage to SARAH-2. Time range: 2005-2016. PVGIS-SARAH will be discontinued by the end of 2022.

PVGIS-NSRDB (0.04º x 0.04º): Result of collaboration with NREL (USA), providing the NSRDB solar radiation database to PVGIS. Time range: 2005-2015.

In addition, there is a worldwide reanalysis database:

PVGIS-ERA5 (0.25º x 0.25º): The latest global reanalysis from ECMWF (ECMWF). Time range: 2005-2020.

Reanalysis of solar radiation data generally has higher uncertainty than satellite-based databases. Therefore, we recommend using reanalysis data only when satellite-based data is missing or outdated. For more information on databases and their accuracy, please refer to the PVGIS webpage on calculation methods.

By default, PVGIS provides solar panels made up of crystalline silicon cells. These solar panels correspond to the majority of rooftop-installed solar panel technology. PVGIS does not differentiate between polycrystalline and monocrystalline cells.

The performance of photovoltaic modules depends on temperature, solar irradiance, and the spectrum of sunlight. However, the exact dependence varies among different types of photovoltaic modules.
Currently, we can estimate losses due to temperature and irradiance effects for the following types of modules:

• Crystalline silicon cells
• Thin-film modules made from CIS or CIGS
• Thin-film modules made from cadmium telluride (CdTe)

For other technologies, especially various amorphous technologies, this correction cannot be calculated here.

If you choose one of the first three options here, the performance calculation will take into account the temperature dependence of the chosen technology. If you choose the other option (other/unknown), the calculation will assume an 8% power loss due to temperature effects (a generic value that has been found reasonable for temperate climates).

Note that the calculation of the spectral variations' effect is currently available only for crystalline silicon and CdTe. The spectral effect cannot yet be considered for areas covered only by the PVGIS-NSRDB database.

Monocrystalline or Polycrystalline?
Monocrystalline silicon is composed of a single silicon crystal, as it is manufactured from a stretched ingot. Polycrystalline silicon is composed of a mosaic of silicon crystals (in fact, residual monocrystalline silicon is used to make polycrystalline silicon).

Monocrystalline solar panels currently have a better efficiency, higher than that of polycrystalline panels, by approximately 1 to 3%.

Monocrystalline solar panels can produce more electricity than polycrystalline ones because they are better at capturing sunlight, even in diffuse radiation. Therefore, they are suitable for regions with less intense sunlight, such as temperate zones.

Polycrystalline solar panels are particularly more efficient in very sunny and hot regions.

Please provide the total power of the installed panels in kilowatts. For example, if you have 9 panels each with a capacity of 500 Watts, you would enter 4.5. (9 panels x 500 Watts = 4500 Watts, which is 4.5 kilowatts)

This is the power that the manufacturer declares the photovoltaic system can produce under standard test conditions, which include constant solar irradiance of 1000 W per square meter in the plane of the system, at a system temperature of 25 °C. The peak power should be entered in kilowatt-peak (kWp).

PVGIS provides a default value of 14% for overall losses in the solar electricity production system. If you have a good idea that your value will be different (perhaps due to a highly efficient inverter), you can slightly reduce this value.

The estimated losses of the system encompass all losses within the system, resulting in the actual energy supplied to the electrical grid being less than the energy produced by the photovoltaic modules.

There are several factors contributing to these losses, including cable losses, inverters, dirt (sometimes snow) on the modules, etc.

Over the years, modules also tend to lose a bit of their power, so the average annual production over the system's lifespan will be a few percentage points lower than the production in the initial years.

There are two installation possibilities: Freestanding/On-Top Installation: Modules are mounted on a rack with free air circulation behind them.

Roof-Integrated/Building-Integrated: Modules are fully integrated into the structure of a building's wall or roof, with little or no air movement behind the modules.

The majority of rooftop installations are currently on-top installations.

For fixed systems (without tracking), the way modules are mounted will influence the module temperature, which, in turn, affects efficiency. Experiments have shown that if air movement behind the modules is limited, the modules can be considerably warmer (up to 15°C at 1000 W/m2 sunlight).

Some mounting types fall between these two extremes. For example, if modules are mounted on a roof with curved tiles, allowing air to move behind the modules. In such cases, performance will be somewhere between the results of the two calculations possible here. To be conservative in such cases, the roof-added/integrated construction option can be used.

You are aware of the tilt angle of your sloped roof; please provide information on this angle.

Optimize slope

This application can calculate the optimal values for slope and orientation (assuming fixed angles throughout the year).

This concerns the angle of the photovoltaic modules in relation to the horizontal plane, for a fixed installation (without tracking).

If you have the opportunity to choose the tilt angle of your mounting system for your solar installation, whether it be on a flat roof or on the ground (concrete slab), you will check the angle optimization.

You are familiar with the azimuth or orientation of your sloped roof; please provide information on this azimuth as follows.

Optimize slope and azimuth

This application can calculate the optimal values for tilt and orientation (assuming fixed angles throughout the year).

The azimuth, or orientation, is the angle of the photovoltaic modules in relation to the direction:

• SOUTH 0°
• NORTH 180°
• EAST - 90°
• WEST 90°
• SOUTHWEST 45°
• SOUTHEAST - 45°
• NORTHWEST 135°
• NORTHEAST - 135°

If you have the opportunity to choose the azimuth or orientation of your mounting system for your solar installation, whether it be on a flat roof or on the ground (concrete slab), you will check the optimization of both the angle and the azimuth.

This is a very approximate option for calculating the cost of produced kWh. This option has no impact on the electricity production calculation, and like any option, it is not mandatory.

The calculated cost of the kWh does not take into account maintenance costs, insurance, and other corrective maintenance costs. The essence of PVGIS is the calculation of the production of your photovoltaic system based on your geographic location and installation information.

Nevertheless, you have the option to calculate, based on the electricity production estimate, the cost of photovoltaic electricity per kWh.

• Cost of the Photovoltaic System: Here, you need to enter the total installation cost of the photovoltaic system, including photovoltaic components (photovoltaic modules, mounting, inverters, cables, etc.) and installation costs (planning, installation, ...). The choice of currency is yours to decide; the electricity price calculated by PVGIS will then be the price per kWh of electricity in the same currency you have used.

• Interest Rate: This is the interest rate you pay on all loans necessary to finance the photovoltaic system. This assumes a fixed interest rate on the loan that will be repaid through annual payments over the system's lifespan. Enter 0 if it is a cash financing, without a loan.

• Photovoltaic System Lifespan: This is the expected lifespan of the photovoltaic system in years. This is used to calculate the effective cost of electricity for the system. If the photovoltaic system lasts longer, the cost of electricity will be proportionally lower. Power purchase agreements with grids are generally for 20 years. We recommend choosing this duration as information about the system's lifespan.

Click to view the results on the screen.

visualize results

Example of solar production month by month.

The result of the photovoltaic energy calculation is the average monthly energy production and the average annual production by the photovoltaic system with the properties you have chosen.

The year-to-year variability is the standard deviation of the annual values calculated over the period covered by the selected solar radiation database.

PV output

Radiation

Export a PDF of the results of your simulation of the performance of your grid-connected photovoltaic system.

By clicking on PDF, you download your simulation.

PDF