Solar panel yield and return
How to estimate solar panel yield, what affects output over the year, and the difference between yield and return.
A rule of thumb in the Netherlands: a panel produces roughly 0.85 to 0.9 times its watt-peak rating in kilowatt-hours per year. A 400 Wp panel lands around 340 to 360 kWh a year.
How do you estimate yield?
A panel's power is rated in watt-peak (Wp). To estimate yearly yield, use a rule of thumb: multiply the total wattage by about 0.85 to 0.9. Ten 400 Wp panels are 4,000 Wp together, so around 3,400 to 3,600 kilowatt-hours per year.
It is an estimate, not a guarantee. Real output depends on your roof and the weather, but for a first read the rule works well.
Yield by season
The sun sits higher and longer in summer, so you generate most between spring and early autumn. In winter, output is much lower. Across a full year it averages out to the figure from the rule of thumb.
What determines your yield?
Four things weigh most: roof orientation (south gives the most, east-west a bit less but spread across the day), the tilt, shade from trees or chimneys, and the quality of panels and inverter.
Shade on part of your roof often costs more than you would expect. We look at this closely during the survey, because sometimes a different layout or a micro-inverter solves it.
Yield versus return
Yield is how much power you generate. Return is what your investment earns: your yield in euros against the cost. The faster you pay back the system, the higher the return.
Because prices and schemes change, we leave hard payback figures off this page and prefer to calculate them for your situation.
Frequently asked questions
We apply this every day
The same knowledge you're reading here, we put to work for households across the Netherlands.
Request a quoteGet started
Solar panels
View and request a quoteRelated articles
What is watt-peak (Wp)?
Watt-peak is the measure of a solar panel's power. What it means and how to convert it into yearly output.
What is a kWh (kilowatt-hour)?
A kilowatt-hour is the unit on your energy bill. What it is, how it differs from kW and kWp, and how much a household uses.
How do solar panels work?
From sunlight to the socket: how solar panels work, what the inverter does, and how you use or feed back the power you generate.
Net metering explained
What the Dutch net metering scheme is, how feed-in is settled, and how to keep your bill low as the rules change.
Monocrystalline vs polycrystalline panels
The difference between mono and poly solar panels and what usually fits best.