Rooftop PV is neither a sure thing nor a swindle — it is an investment that has to be computed honestly. This piece separates the defensible figures from the marketing — politely, but clearly.
According to surveys by independent energy research, the generation cost of small rooftop systems is typically around 6–14 ct/kWh, while grid electricity for households often costs 30–40 ct/kWh. The biggest lever is therefore self-consumption: every kilowatt-hour used yourself saves considerably more than feeding it in earns (currently only around 7.7–7.8 ct/kWh for partial feed-in, and still falling). For anyone who consumes little themselves and feeds in a lot, the arithmetic turns thin.
With a battery and high self-consumption (heat pump, electric car, daytime use), sensibly sized systems often pay back in 10–15 years; after that the electricity runs largely free of charge. Without high self-consumption, and on pure feed-in, it becomes markedly thinner — especially as negative exchange prices become more frequent and the tariff keeps falling.
The large providers who bundle PV with zero down payment, full service and a 20-year contract are mainly selling comfort and financing — not the cheapest kilowatt-hour. Over the term, such rental and financing models are noticeably more expensive than buying outright; independent consumer tests put the extra cost at 30–80 % depending on the calculation. Advertised low tariffs and savings promises often do not hold in practice, the assumptions on self-consumption and price rises tend to be optimistic, and a 20-year commitment is risky if the house is sold or the technology ages. For anyone with neither capital nor time, such a model can hold fair value. But anyone who computes it themselves — or has it computed — is usually markedly better off buying. That is exactly where we come in: the honest, reproducible figure instead of an optimistic offer.
Private rooftop PV is not a game changer for the global climate; its contribution is mainly local. The real lever sits with industry, large-scale generation, heat and transport. The energy transition needs scalable, cost-efficient solutions — large PV and wind farms, better networks, storage, realistic carbon pricing. This is not a rejection of PV but an argument for directing capital to where each euro does the most good — and that is exactly what EXAIOS computes, for every case.
EXAIOS returns the decisive figures for every site:
We publish no invented numbers. Compute your real site in minutes — the first indication is free.
Start a free indicationFor most people with some capital or a subsidised loan, buying is clearly cheaper. The large all-inclusive providers mainly sell comfort and risk transfer — that has value, but over 20 years it costs noticeably more. What decides is computing your own figures honestly.
Then self-consumption alone carries the economics. For households with low self-consumption, PV then often stops paying off — the lever is to raise self-consumption (heat pump, electric car, battery), which itself costs money.
As an individual investment, often reasonable — if you compute your own figures honestly (roof orientation, consumption, financing) rather than believing the marketing. As climate rescue it is overrated; the big lever sits with industrial and grid-scale solutions.