Solar panel calculator: how much electricity and what economics?
The economics of a solar installation depend both on the production and on when you use the electricity. Here you can examine an installation with the nearest Danish town, roof direction, pitch and your expected self-consumption.
Worked example
- Nearest town: Aarhus
- Direction: South
- System size: 6 kWp
- Slope: 35 degrees
- System loss: 14 %
- Self-consumption: 50 %
- Price paid for electricity: 2.00 DKK
- Sale price: 0.50 DKK
- Running costs: 500.00 DKK
- System price: 60,000.00 DKK
- Lifetime: 25 years
- Annual payment decrease: 0.5 %
Production
5,817.1 kWh per year
Self-consumption 2,908.55 kWh · sold 2,908.55 kWh
Value in the first year: 6,771 DKK · over 25 years 158,784 DKK · payback about 8.8608 years
Self-consumption is your estimate (a rough model, not hour by hour). Production: PVGIS (EU JRC), typical year.
Self-consumption and sales have different values
Electricity you use directly from the installation can replace purchases from the grid. Surplus electricity is sold at other prices and terms. The whole production can therefore not be valued as saved electricity at the full purchase price. Fixed payments do not necessarily disappear either.
The calculator shows estimated production, self-consumption, export and economics. Installation price, running costs and any replacements are included in the chosen period. The production estimate is not a guarantee for each individual year.
How to assess a solar panel offer
Check the roof details
Enter the roof’s actual orientation and pitch. Shade from trees, buildings or parts of the roof can affect production. Use a documented assessment if there is significant shade.
Example of the value of the electricity
If you use 2,000 kWh yourself at an avoided price of 2 DKK per kWh, the value is 4,000 DKK. If another 2,000 kWh are sold net at 0.50 DKK, that gives 1,000 DKK. The total is 5,000 DKK before other items.
Try changes in the electricity price, self-consumption and installation price. This shows whether the economics hold under other assumptions. If you are considering a battery, the battery calculator can isolate the extra investment and examine whether the shifted consumption gives enough value.