Are Solar Panels Worth It? Payback, Savings and When They Aren't

If you have a sunny, unshaded roof and pay a mid-to-high electricity price, solar panels are one of the few home improvements with a predictable positive return. Not every house qualifies, though. The economics come down to five numbers: installed cost, local sunshine, retail electricity price, how much of the output you use yourself, and what you earn for the rest. Below you’ll find realistic ranges for each, how to combine them, three worked examples, and the situations where solar doesn’t pay.

The five numbers that decide the answer

Installed cost ranges come from IRENA’s cost reports and LBNL’s Tracking the Sun series. Real quotes vary widely with country, roof complexity and installer margin. Countries where installation is cheap (Germany, the Netherlands, Australia) sit at the low end. Markets with high soft costs such as permits and customer acquisition, above all the US, sit at the high end.

The core calculation

Watch the blended value per kWh. If it sits well above the system’s levelised cost per kWh, solar pays.

What does solar electricity cost to produce?

Divide the installed cost plus maintenance by all the kWh a system produces in its life and you get the levelised cost of electricity (LCOE). Ignoring financing, a €7,500 system of 6 kWp yielding 1,100 kWh/kWp for 25 years with 0.5%/year degradation makes about 155,000 kWh: roughly €0.05–0.06/kWh in hardware, or €0.06–0.08 including an inverter replacement and maintenance. With a 5% cost of capital, the figure rises to about €0.08–0.10/kWh. The LCOE calculator handles discounting properly; our LCOE explainer covers the method.

Grid electricity at €0.25–0.35/kWh costs several times more. The catch is that you have to use the energy yourself or get a fair price for exporting it.

Worked example: three households

All three install 6 kWp at €1,250/kWp (€7,500), with €80/year maintenance and an inverter replacement after about 12 years.

Household A still gets its money back well within the panels’ life, but its 25-year net gain is less than half of B’s. The only difference is when they use electricity. Moving the dishwasher, washing machine, EV charging and hot-water heating into daylight hours is often the cheapest upgrade there is. The solar panel calculator simulates your own case hour by hour with real weather, and the net metering calculator compares export schemes side by side.

Export rules can make or break the case

Many countries started with generous feed-in tariffs or 1:1 net metering, then cut export rates as solar grew:

• Full net metering (each exported kWh offsets an imported kWh at retail value) makes self-consumption irrelevant and gives the fastest payback.
• Net billing / feed-in at wholesale pays €0.03–0.10/kWh for exports, sometimes varying by time of day. Self-consumption then drives the result.
• Zero or negative export value at midday is spreading wherever solar saturates the grid. There, an array bigger than your daytime use adds little.

Before you buy, find out exactly how your utility or regulator values exports, and how likely the rules are to change over the system’s life. Our country energy profiles give the national context.

Should you add a battery?

A battery stores the midday surplus for the evening and typically lifts self-consumption by 20–40 percentage points. Each cycle is worth the spread between retail and export price.

The example assumes the battery is filled and emptied on 250 days a year. That’s realistic in summer and optimistic in a northern winter. Batteries pay back faster with time-of-use tariffs (charge cheap, avoid the peak), where exports earn almost nothing, or where backup during outages is worth real money. Size yours with the solar battery calculator and read the home battery storage guide.

When solar panels are not worth it

Think twice if any of these apply:

1. Heavy shading. Trees, chimneys or neighbouring buildings that shade the array for hours in the morning, afternoon or winter can cut yield by 20–40%.
2. The roof needs replacing soon. Taking panels off and refitting them usually costs several hundred to a few thousand euros. Re-roof first.
3. Very cheap electricity. At retail prices below about €0.12–0.15/kWh with low export rates, payback can exceed 15 years.
4. Poor orientation and low pitch to the north at high latitudes. A north-facing 40° roof at 52°N produces roughly 55–65% of an optimal one.
5. Overpriced quotes. If a quote is far above the usual range for your country, get two more. Installed cost moves payback more than anything else.
6. You’ll sell soon and don’t expect the sale price to reflect the system.
7. Leases or PPAs with escalators. Third-party ownership can work, but annual price escalators of 2–3% eat into savings. Read the contract carefully.

Things that make solar more worth it

• Electrifying heating (heat pump) and transport (EV) raises daytime demand and self-consumption. See the heat pump calculator and EV charging cost calculator.
• Right-sizing. Match the array to your annual use and the value of exports. How many solar panels do I need works it out from your bill.
• Incentives such as tax credits, VAT exemptions or grants can cut net cost by 10–30%.
• Rising retail prices. Each rise in the grid price makes every self-consumed kWh worth more.

Cash, loan or lease?

How you pay changes the return:

A quick test for financing: if the annual loan repayment is below year-1 savings, the system is cash-flow positive from day one. At 6% over 10 years, the €7,500 system above costs about €1,020 a year. That is just below household B’s savings but above household A’s. The solar panel calculator reports NPV and IRR, so you can compare solar with leaving the money in a savings account. Well-sited systems often reach an IRR of 8–15%, comfortably above most deposit rates.

Sensitivity: what moves payback most

For a typical European system, a ±20% change in installed cost shifts payback by about ±20%. The same change in retail price or self-consumption shifts it by roughly 15–20%. A ±20% change in export rate moves it by only 5–10% when self-consumption is high, and degradation and maintenance matter least. So spend your effort on competitive quotes and on using more of your own power.

Non-financial considerations

Rooftop solar also cuts emissions. Lifecycle assessments compiled by the IPCC and others put crystalline silicon PV at roughly 20–50 g CO₂-eq per kWh, depending on where modules are made and installed. Gas comes in around 400–500 g and coal around 800–1,000 g. The CO₂ your panels actually avoid depends on your grid’s carbon intensity. Check it with the electricity CO₂ calculator or compare grids on the world energy map and rankings.

Verdict

Solar panels are worth it when three things hold. The blended value of each kWh (weighted by how much you self-consume and what exports earn) comfortably exceeds about €0.08–0.10/kWh. The roof is sound and mostly unshaded. And the installation price is in line with your market. Then a 5–10-year payback on a 25–30-year asset is normal. If any condition fails, fix it first by shifting demand, re-roofing or collecting more quotes, or put the money somewhere else.

Figures in this guide are typical ranges drawn from the sources above; your own numbers depend on location, prices and equipment. Use the linked calculators for site-specific estimates.