Solar panel annual yield: kWh and benefits

A panel's power is rated in watt-peak (Wp). To estimate yearly yield, multiply the total wattage by about 0.85 to 0.9. That gives kilowatt-hours (kWh) per year. It is an estimate: your roof, orientation and the weather determine the real result.

Common panels now often sit around 435 Wp. The examples below assume a south-facing roof at about 36 degrees and follow the yield assumptions Milieu Centraal uses.

In the Netherlands a solar installation produces most of its yearly yield between March and September. A top month like June easily produces over four times as much as December. Over a full year that averages out to the rule of thumb of 0.85 to 0.9 kWh per Wp.

Diffuse light in spring and autumn still generates output. You don't need a heatwave: bright but cool spring weather often gives a great result, because cells work slightly more efficiently at lower temperatures.

Four things weigh most on your yearly yield: roof orientation, tilt, shade from trees or chimneys, and the quality of panels and inverter. On a pitched roof, an angle between 20 and 50 degrees is usually favourable. South gives the highest peak; east-west spreads output better across the day, which often matches your usage more closely.

Shade on part of your roof often costs more than you would expect. We look at this closely during the survey. Sometimes a different layout or an Enphase micro-inverter solves it, so shade on one panel does not drag down the whole system.

Yield in kWh is step one. Financially, what matters is how much of that power you use yourself. An average household uses about 30 to 35 percent of its solar power directly, Milieu Centraal estimates. The same source calculates that power from your own roof works out roughly three to four times cheaper over the system's lifetime than power you buy in.

What you don't use straight away goes back to the grid. While the net metering scheme runs, that feed-in is offset against your draw and worth the same as purchased power. For the surplus beyond your draw, and after net metering ends in 2027, you receive a feed-in payment that is usually much lower. Read our dedicated page or the ACM explanation of net metering.

Want to use more of your own generation? An east-west layout or a home battery helps. How much you save depends on your usage, your contract and the schemes at the time. That is why we prefer to calculate it for your situation rather than promise a fixed amount.

You don't always have to make the investment in one go. Through the national Warmtefonds you can finance home improvements, including solar panels, on favourable terms. You spread the cost over several years while already saving on your energy bill once the panels are running.

On our solar panels page we explain how financing works and what you need to apply. No down payment at SolarFast: you pay after installation.

A home with low energy costs and a better energy label appeals to buyers. Panels are not only a saving on your monthly bill, but also an investment in your property. How much that adds in euros varies by home, market and label; financially you gain mainly through lower power costs and more self-use.

For private homeowners a favourable VAT regime applies: supply and installation of solar panels on or at a home has been charged at 0 percent VAT since 1 January 2023. Exceptions apply, for example integrated panels on new-build homes. Current rules are on the Dutch Tax Administration site.

Panels typically last 25 years or more, with a slight yearly drop in output. Whether and when your investment pays back depends on your usage, your roof, purchase costs and the rates and schemes at the time. There is no fixed term that fits everyone; that is why we calculate it for your situation rather than promising a generic number.

In your quote we calculate payback based on your actual situation. No fixed promise on paper, but figures tailored to your roof and usage. Ask us if you want to discuss your situation first.