Skip to main content

Enter the size of the system in kWp, the average peak sun hours per day at your location and the performance ratio. You get the production per day, month and year, and what it is worth. It is an estimate for planning, not a yield guarantee.

Enter your values

Peak power of all panels together: number of panels × watts per panel ÷ 1000.
Where do I find this?

Multiply the number of panels by the watt-peak of one panel, then divide by 1000: 12 panels × 420 Wp = 5.04 kWp.

The offer or the inverter documents also state the kWp.

Yearly average of the daily solar energy in kWh/m². Look up your location.
Where do I find this?

Peak sun hours equal the daily solar irradiation in kWh per m². The European Commission's free PVGIS tool (re.jrc.ec.europa.eu/pvg_tools) gives it for any location.

Averaged over the year it is often around 2.5 to 3.5 in Central Europe, higher in the south. 3 is an example.

Share of the ideal output that remains after losses. Often 75 to 85 %.
Where do I find this?

The performance ratio covers inverter, cable, temperature and shading losses. Well-built systems are often around 80 %.

Use a lower value for shading or a poor roof angle.

What a kWh is worth to you: the electricity price you avoid buying, or the feed-in tariff.
Where do I find this?

For power you use yourself, use your electricity price per kWh. For power you feed into the grid, use the feed-in tariff.

The Solar Payback Calculator mixes both.

Only changes the symbol; no exchange rate is applied.

Result

Enter your values to see the result.

Production per year
– kWh
Per month
– kWh
Per day
– kWh
Yield per kWp and year
– kWh/kWp
Value per year
–

Want this tracked for you? UtilityControl logs your meters and costs automatically.

How it is calculated

  • Energy per day (kWh) = system size (kWp) × peak sun hours × performance ratio ÷ 100
  • Per month = per day × 365 ÷ 12; per year = per day × 365
  • Yield per kWp = peak sun hours × 365 × performance ratio ÷ 100

Example

A 5 kWp system with 3 peak sun hours and an 80 % performance ratio makes 5 × 3 × 0.8 = 12 kWh a day, about 4,380 kWh a year.

What this estimate leaves out

Real production varies with the weather from year to year, with roof angle and direction, shading and panel ageing. For a precise yield of your roof use a tool such as PVGIS or ask your installer for a simulation.

Written and reviewed by QLines, Cologne · Last reviewed

Read the PV and heat pump planning guide (German)

FAQ

Frequently Asked Questions

How much electricity does a solar panel produce?

It depends on the system size and the sun at your location: kWh per day = kWp × peak sun hours × performance ratio. A 5 kWp system with 3 peak sun hours and 80 % ratio makes about 12 kWh a day.

What are peak sun hours?

The number of hours per day with the full 1 kW/m² of sunshine that would give the same energy as the real day. It equals the daily solar irradiation in kWh per m². Look up your location in PVGIS.

What is kWp?

kWp (kilowatt-peak) is the output of the panels under standard test conditions. It is the usual way to state the size of a solar system.

What is the performance ratio?

The share of the ideal output that is left after losses in the inverter, cables, temperature and shading. A good system often has about 75 to 85 %.

More free calculators

Solar Payback Calculator

How many years until your solar system has paid for itself? Cost, production, own use and tariffs.

Electricity Cost Calculator

What does a device cost to run? Watts, hours and your price give the kWh and the cost per day, month and year.

Track your meters instead of calculating by hand

UtilityControl keeps your readings, usage and costs for every meter and location, and it starts free.

See UtilityControl Pricing