In short
A PV system is worth the discounted surplus it will still generate until decommissioning, minus inverter replacement and removal. Age and purchase price say little. A 15-year-old commercial system with a high feed-in tariff can be worth more than a newer system with defects.
Calculator: estimate the value of your PV system
Enter the figures from your feed-in statement. Once you have confirmed your email address, you receive the income value as of 1 January of next year with a range, a sensitivity analysis and annual cash flows as a PDF. The calculator uses the same building blocks as our valuation reports but knows neither the condition of the system nor your contracts.
What determines the value of a PV system?
- Revenue until the end of the feed-in tariff Under Germany's Renewable Energy Sources Act (EEG) the tariff runs for 20 years plus the year of commissioning. For systems built between 2009 and 2012, most of the value lies in these final years.
- Revenue afterwards Systems whose tariff has expired receive the annual solar market value minus a marketing fee; the annual market value was 4.51 ct/kWh in 2025 (Verbraucherzentrale, in German). Self-consumed electricity saves the purchase price.
- Self-consumption At 25 to 35 ct/kWh grid price, every self-consumed kilowatt-hour is worth several times the feed-in revenue.
- Actual yield We work with meter readings, not design forecasts. Degradation, shading and faulty strings show up there.
- Inverters Replacement is usually due after 10 to 15 years. If it has already been done, the value rises.
- Costs Maintenance, insurance, metering, direct marketing, roof lease.
- Remaining useful life Modules, mounting structure, roof and lease contract set the end date. An upcoming roof renovation often shortens it more than module age does.
- Discount rate It reflects risk and cost of capital. One percentage point shifts the value by 3 to 10 %, depending on the remaining term.
Which value do you need?
Buyers, banks, insurers and courts ask for different values depending on the occasion. The figures can be far apart.
Why rules of thumb mislead
Percentages of the purchase price circulate online, such as "5 to 10 % after 20 years". They ignore that value depends on future revenue, not on the historical price. Two examples from our model calculations:
- A 250 kWp commercial system from 2011 comes to around €205,000. Almost 98 % of that comes from the five remaining tariff years. After the tariff ends, it barely covers its own costs at 4.5 ct/kWh.
- A 10 kWp system on a single-family home from 2012 is worth around €18,000. Without self-consumption it would be only €10,100.
Both calculations with all annual figures are on the page on remaining value.
Sensitivity: what moves the value most
For the commercial system in the example, individual assumptions change the value as follows:
| Assumption | Value | Change |
|---|---|---|
| Base case (5.5 % discount rate, 960 kWh/kWp) | €205,000 | – |
| Yield −10 % | €173,800 | −15 % |
| Yield +10 % | €236,500 | +15 % |
| Discount rate +1 percentage point | €199,100 | −3 % |
| Discount rate −1 percentage point | €211,200 | +3 % |
| Inverter already replaced | €235,800 | +15 % |
Yield matters more than the discount rate. That is why our reports start with the measured data and the technical condition before any discussion of rates.
Calculator or valuation report: when is which enough?
The calculator is enough for a first, static estimate. It does not take current market movements into account. You need a valuation report before talking to a prospective buyer and whenever a third party relies on the value: a bank, the tax office, a court, an insolvency administrator or an insurer. We then inspect the system on site (thermography, electroluminescence, IV curves), analyse yield data and contracts and disclose every assumption.
Frequently asked questions
How much is a PV system worth after 10 years?
That depends mainly on the tariff and the ten remaining tariff years. Systems from 2014 to 2016 with 12 to 13 ct/kWh still have ten secured tariff years ahead, and these carry the value. A percentage of the purchase price is not a useful yardstick.
How much is a PV system worth after 20 years?
Once the tariff has ended, only market value, self-consumption and costs count. Systems that feed in everything are then often worth little, systems with high self-consumption considerably more. What matters is how long modules, roof and inverters will last.
What data do I need for the calculator?
System capacity, year of commissioning, tariff rate and the kilowatt-hours fed in over recent years from the grid operator's statement. With self-consumption, also the share and your electricity price.
Is the calculator result binding?
No. It is an indicative calculation based on your inputs. For a purchase, sale, financing, insurance or court you need a valuation report with an on-site inspection.
Who can establish the value of a PV system as an expert?
An expert for photovoltaics with valuation experience. We combine the technical inspection on site with the economic valuation, so both are covered in one report.