How much energy does a solar panel produce in Tarragona? Month-by-month data

Knowing how much your installation should produce is the best tool for spotting problems. To work it out we use PVGIS, the free tool from the European Commission's Joint Research Centre, which estimates solar production from satellite radiation data [1].

Month-by-month production in Tarragona

This is the PVGIS calculation for Tarragona with 1 kWp of power, south-facing panels at the optimal tilt (38°) and 14% system losses [1]:

How to estimate your panels' output

Multiply your installation's power in kWp by 1,583. Some examples:

• One 450 W panel (0.45 kWp): about 710 kWh a year.
• A home with 4 kWp: about 6,330 kWh a year.
• A warehouse with 50 kWp: about 79,100 kWh a year.

These are estimates for optimal conditions. If your panels face east or west, have a lower tilt or are shaded, real output will be lower. You can run your own calculation in PVGIS by entering your address.

Summer produces more, but not everything it could

In the PVGIS calculation, May to August are the highest-producing months, with July slightly ahead of June. Note that in summer the cells get very hot and lose some efficiency due to temperature [2]; even so, radiation is so high that these remain the most productive months. We explain this in our article on heat.

Use this figure to spot problems

Compare what your inverter shows with the table. If, in a clear month, you produce clearly less than expected, the most common causes are:

• Dirt: dust, Saharan dust, agricultural dust or droppings. Worldwide it accounts for a 3–5% loss of production, and more in dry areas [3].
• New shading: trees that have grown, aerials or nearby buildings.
• Faults: a damaged module, a loose connector or an inverter failure.

As a solar panel cleaning company in Tarragona, on every job we check the condition of the modules and give you a photo report, so you know whether the loss was dirt or something else.