Wertermittlung Photovoltaikanlage: Methoden, Faktoren & Gutachten
Whether when acquiring an existing system, when selling a property with a PV system on the roof or after an insurance claim – the question of the value of a photovoltaic system arises more often than one might think. The answer is rarely simple because value is not the same as purchase price. This article explains the common valuation methods, the decisive influencing factors and the role of thermography in a well-founded valuation.
Wann wird eine Wertermittlung benötigt?
A valuation for a PV system is relevant in various situations. It most frequently arises in connection with Immobilientransaktionen : anyone buying or selling a house with a solar installation wants to know what the system actually contributes to the property value. This is by no means self-evident – a poorly maintained, defect-ridden system can also burden rather than increase the value of a property.
Bei standalone PV systems and solar farms the valuation is part of every serious transaction. Investors, funds and developers acquire existing systems on the basis of a structured technical and economic assessment. Valuation also plays a role in Versicherungsschäden , when current value or replacement value must be determined, and in inheritance and divorce proceedings, where PV systems are assessed as assets. An increasingly relevant special case is the takeover of a PV system after expiry of a roof lease contract – here the residual value must be determined particularly carefully to assess the economic viability of the takeover.
Auch beim Ablauf der Einspeisevergütung after 20 years of EEG subsidy the question arises: how much is the system still worth, and is continued operation or reinvestment worthwhile? Precisely when decisions of economic significance need to be made, a reliable basis is needed.
Die drei Bewertungsmethoden im Überblick
The income value is derived from the capitalised future yield of the system – i.e. the present value of all expected income from grid feed-in or self-consumption over the remaining service life. This method is the most relevant for commercial systems, solar farms and transactions because it directly maps the economic benefit. The decisive inputs are annual yield (kWh), electricity value (feed-in tariff or self-consumption value), degradation rate and remaining service life.
The replacement value is based on the replacement cost of a comparable new system, less a depreciation for age. This method is primarily used by insurers for determining the current value and is common for private systems and smaller rooftop systems. The replacement value does not reflect the economic value, however – an old system with low yield can be attractive despite a low replacement value if the tariff is high.
The comparative value is derived from market prices for comparable transactions. This method has only limited applicability for PV systems because the market is fragmented and comparative values are rarely transparently available. It is occasionally used as a supplement to check plausibility – as the sole valuation basis it is unsuitable for PV systems.
Wertbeeinflussende Faktoren
Der Wert einer PV-Anlage hängt von einer Vielzahl technischer und wirtschaftlicher Parameter ab:
The rated power in kWp is the starting point of every valuation. What is relevant, however, is the actually achievable power – not the installed rated power of a system with defects.
Historical monitoring data shows whether the system delivers the expected yields. Deviations of more than 5% from the specific yield are a warning signal.
The condition documented by thermography is the most important single factor. Defective modules, overheated junction boxes and degradation reduce the value directly and quantifiably.
Systems with a high EEG feed-in tariff from the years 2010–2013 are economically more valuable than newer systems with a lower tariff – even at the same age.
Sunshine hours, orientation, tilt angle and shading situation determine yield potential. The specific yield (kWh/kWp) is the most important location indicator.
Complete documentation (commissioning log, maintenance evidence, thermography reports) considerably increases the value. Incomplete documents reduce it – or make a valuation impossible.
Modules typically have a 25–30 year service life. Inverters 10–15 years. How many years remain in the system, and which components will need to be replaced soon?
Brand manufacturers with proven quality and active warranty services are more valuable than unknown manufacturers. The insolvency of a module manufacturer renders guarantee claims worthless.
Die Rolle der Thermografie bei der Wertermittlung
A valuation without thermographic condition assessment is like a property valuation without an inspection. A value can be stated – but it is speculative. Thermography delivers the only objective, complete recording of the technical condition of a PV system during operation.
Specifically a professional thermographic assessment to IEC TS 62446-3 delivers the following information for the valuation: the number and type of defective modules, the current yield loss in kWh or percent, a qualified estimate of the remediation costs and an assessment of the degradation and remaining service life. All of these are direct inputs for the income value – without these data the expert is working with assumptions.
In transactions a current thermographic assessment builds trust on both sides: the seller can market a proven condition, the buyer can decide on the basis of real data. Defects discovered only after the purchase regularly lead to disputes – a thermographic assessment prepared in advance prevents this. More on this in the article on Technical Due Diligence für Solarparks.
Wann brauchen Sie ein formelles Gutachten?
A thermographic inspection is not an expert report in the legal sense – it is a standards-compliant technical inspection. A formal expert report is needed when the result is to be used in a legal context: in court, in arbitration proceedings, against an insurer or as a basis for a bank financing decision.
For a court-admissible expert report the expert must be publicly appointed and sworn in. The thermographic report to IEC TS 62446-3 is typically one of the key attachments – it documents the technical condition objectively and to standards. An expert who dispenses with thermography cannot assess the technical condition of a system professionally.
| Anlass | Empfohlene Methode | Thermografie nötig? |
|---|---|---|
| Anlagenkauf/-verkauf | Ertragswert + technische Prüfung | Ja – unverzichtbar |
| Versicherungsschaden | Sachwert (Zeitwert) | Ja – Schadensnachweis |
| Finanzierung / Bank | Ertragswert | Ja – Risikobewertung |
| Immobilienbewertung | Sachwert oder Ertragswert | Empfohlen |
| Erbschaft / Scheidung | Sachwert oder Ertragswert | Empfohlen |
| EEG-Auslauf / Weiterbetrieb | Ertragswert (Restlaufzeit) | Empfohlen |
Technische Zustandsbewertung anfragen
For a well-founded valuation you need standards-compliant thermography. Contact us – we will prepare an individual quote for your system.
Anfrage stellen →Frequently asked questions
The value is determined via income value (capitalised future yield), replacement value (replacement cost minus age depreciation) or comparative value. For transactions the income value is usually decisive because it directly maps the economic benefit.
The most important factors are installed power, actual yield history, technical condition (documented by thermography), remuneration structure, location quality and remaining service life.
A formal expert report makes sense for insurance claims, legal disputes, bank financing and larger transactions. A thermographic report to IEC TS 62446-3 is typically one of the key attachments.
Thermography delivers the objective evidence of the technical condition – defects, yield loss and remediation costs. Without thermographic condition assessment a valuation remains speculative.
Conclusion
The valuation of a photovoltaic system is not a purely mathematical process – it requires a solid technical basis. The most important step is capturing the actual condition through a standards-compliant thermographic inspection. Only then can yield losses be quantified, remediation costs estimated and a reliable value determined.
Anyone wanting to buy or sell a system will find further information in our article on Technical Due Diligence . For the technical basis – thermography – we are available on request.