That is the rise in electricity prices in ten years
Your own production, once installed, costs nothing more.
Eurostat, ménages UE, 2015 → 2025Solar panels: are they worth it for your home? – an answer in numbers, in thirty seconds
Your own production, once installed, costs nothing more.
Eurostat, ménages UE, 2015 → 2025Depending on the country. The simulator works it out from your bill.
Prix de détail Eurostat, 2e sem. 2025Twenty times less than coal.
Fraunhofer ISE, 2026Thirty seconds to find out whether it pays off at your home.
Compare the best solution for your home in one minute: size, cost, output and payback.
The installation guide shows you, step by step, how this installation is mounted and connected. The declaration dossier lists the steps for your country, pre-filled with the characteristics above.
How a solar installation works – components, mounting, production and vocabulary
Eight minutes to know what we are talking about: the components, the mounting options, what makes output vary, and the vocabulary you will find on quotes.
Pick a type of installation: the diagram shows the equipment required and the path electricity takes, from the roof to your sockets.
The kWp (kilowatt-peak) measures the size of the system, like engine displacement: 1 kWp is about two panels and 5.5 m² of roof. The kWh measures the energy actually produced or used — what your supplier bills. Between the two sits a single figure: specific yield, the number of kWh one kWp produces where you live in a year. From Helsinki to Valletta it already varies twofold.
For the same specific yield, two roofs are not equal: orientation, tilt and shading make the difference. Move the sliders: the curve shows the power produced through the day, in winter, mid-season and summer, at your latitude.
A panel's cells sit in series: the current is that of the least lit cell. A small shadow therefore throttles a whole group of cells, and on a string inverter the whole panel can get dropped. Move the shadow and watch what is left.
Over the year, a chimney on an eight-panel array typically costs 10 %; micro-inverters recover 4 to 12 % depending on the shade (NREL measurements). Winter shadows count for little: the ones to avoid are those from April to September, between 10:00 and 16:00.
A panel produces most when the rays strike it head-on. But the noon sun is not at the same height at every latitude or season: tilting the panel turns it towards where the sun passes most often. Drag the sliders.
A panel rated 1 kWp almost never delivers 1 kW. Between the nameplate rating and the electricity reaching the meter sit well-known losses, whose sum is called the performance ratio.
You have the vocabulary. Now let us see what it means at your place, with your own figures.
Install your system – three installations, step by step, for a private individual
Mounting depends first on what you are mounting onto. Select your surface.
On a terrace or flat roof, the modules sit on ballasted trays tilted at 10 to 15°, facing south or back-to-back east-west. The ballast — paving slabs or concrete blocks — is what holds the whole assembly down in the wind; its weight is calculated with the manufacturer's configurator according to the wind zone, the height of the building and the position on the roof. Do not guess that figure.
The rest — wiring, inverter, consumer unit — is identical to a pitched-roof installation. A guard rail or a harness is always needed: a flat roof is still a roof.
Ground mounting is the most comfortable — no height, no waterproofing — but it needs space and a trench.
Check that your meter does not run backwards: an old electromechanical meter must be replaced before commissioning. And in a block of flats, a vote may be needed: ask the managing agent before buying.
An 800 W plug & play kit has nothing in common with the above: no high DC voltage, no isolator switch, no surge protective device, no work on the roof. Two panels, a microinverter, a socket. The installation takes half a day and the only real mechanical risk is the wind load on a balcony railing.
The rules differ sharply from one country to another. Germany has set a clear framework — 800 VA at the inverter output, simplified registration in the national register, and no further notification of the network operator. Belgium has allowed these kits since April 2025, with a declaration above 800 W. Italy regulates them from 350 W upwards. France has no legal threshold: the 800 W seen everywhere is a market practice imported from Germany, and the 2024 edition of NF C 15-100 even states that a generator should not be connected through a socket outlet — an acknowledged grey area. In every case, declaring the system to the network operator is free and mandatory: forgetting to do so hands your insurer a reason to refuse a claim.
Without the grid, the inverter-charger supplies its own switchboard, with its circuit breakers per circuit and its residual-current device. There is no meter and no main service breaker: you are the supplier. Three points are non-negotiable:
An off-grid site can be installed without a licensed firm almost everywhere in Europe, including Italy and Spain. But it is the most demanding installation of the three, and the one where a mistake costs weeks without electricity.
Four checks, in this order, before connecting the inverter.
| Open-circuit voltage of the system | Test voltage | Minimum insulation |
|---|---|---|
| below 120 V | 250 V DC | 0.5 MΩ |
| 120 to 500 V | 500 V DC | 1 MΩ |
| above 500 V | 1000 V DC | 1 MΩ |
A 6 kWp system in a single string exceeds 500 V: test at 1000 V, one megohm minimum. Finally, check the continuity of the earthing, from the frames through to the earth bar in the consumer unit.
The calculator's quote gives you the power, the number of modules and the battery suited to your home — and prepares the declaration dossier.
Method and sources – where the figures come from, and how they are combined
This calculator is not a black box. Every figure it shows comes out of an explicit calculation applied to public data you can go and check yourself. Here is which data, and what we do with it.
The starting point is the country's specific yield: what one kilowatt-peak of panels produces in a year, tilted and oriented at best, in kWh/kWp/year. The reference values come from PVGIS, the European Commission's tool, cross-checked against the Global Solar Atlas.
If you enter an address, the calculator queries two open climate databases — Open-Meteo's ERA5 archive, with NASA POWER climatology as a fallback — to retrieve the irradiation actually measured at that point, and replaces the national average with that local value. This is why the same house does not give the same result in Inverness and in Plymouth.
Orientation and tilt then apply a factor running from 0.45 (due north, steep pitch) to 1.00 (due south, optimal pitch). That optimal pitch is calculated from your latitude, not fixed once and for all.
Producing is not the same as consuming. The share of your output that you use on site — the self-consumption rate — depends on the ratio between what you produce and what you consume, and on the time of day when you consume it.
The calculator applies k ÷ (k + production ÷ consumption), with k at 0.80 if you consume mostly during the day, 0.45 for a spread-out profile, 0.28 in the evening and at night. It is a classic form, fitted to residential load curves: the larger the system is against the need, the more the directly consumed share collapses. That is exactly why oversizing without a battery earns almost nothing.
With a battery, a second pass recovers the surplus from the sunny hours, up to the installed capacity and the evening demand.
An installation does not cost in proportion to its size: the fixed costs — travel, scaffolding, inverter, grid connection, surveys — are diluted as it grows. The calculator starts from a reference price in €/kWp for each country, then applies a tapering coefficient: 1.35 below 3 kWp, 1.15 from 3 to 6, 1.00 from 6 to 10, 0.80 from 10 to 50, then 0.65 and 0.55 above that.
The mounting method and the roof covering adjust the result: fitting onto tiles costs more than onto steel sheet, and a ballasted mount on a flat roof more than a ground mount. If you fit the system yourself, only the hardware is counted, plus 4% for small supplies.
The reference prices for the six documented countries are aligned with the sources listed below. For the other countries they are orders of magnitude, to be confirmed by a local quote.
The price per kilowatt-hour is the Eurostat one, series nrg_pc_204, band DC households (2,500 to 4,999 kWh a year), all taxes included, second half of 2025. It is the only series that is genuinely comparable from one country to another.
The value of the surplus exported to the grid is expressed as a share of that retail price, and it moves fast. In June 2026 France went from a self-consumption bonus and a comfortable feed-in tariff to a single rate of 1.1 euro cents per kWh. The Netherlands lose salderen on 1st January 2027. The values used target the regime that will apply to a system commissioned now, over its lifetime — not the one that is being phased out.
The payback time is the number of years after which the cumulative savings cover the investment. The internal rate of return is calculated over 25 years, with module degradation of 0.5% a year and an electricity price rise of 2% a year.
No public subsidy enters the calculation: they change too often and depend too much on your situation. The country pages describe them one by one. The figure shown is therefore a floor, which any support you are entitled to can only improve.
All the data below is public and verifiable. The date shown is that of the version used.
nrg_pc_204 — Prix de l'électricité, ménages bande DC (2 500–4 999 kWh/an), toutes taxes comprises, 2e semestre 2025.Legal notice – publisher, hosting, liability
The site is hosted by Netlify, Inc., 512 2nd Street, Suite 200, San Francisco, CA 94107, United States — netlify.com. The pages are served from the host's delivery network, which includes servers located in the European Union.
The text, diagrams, illustrations and code on this site belong to the publisher, with the exception of the public data cited on the “Method and sources” page, which remains subject to the licences of its producers.
The results you obtain are yours: you can save them, print them, share them and pass them to an installer without any restriction. The country dataset is published for free reuse.
This site provides an estimate, built from public averages and the information you enter. It is not a quote, not a technical study and not investment advice, and it binds no installer.
Prices, subsidies and feed-in tariffs change constantly and vary with the region, the age of the property and your tax situation. No investment decision should rest on this alone: obtain at least two detailed quotes and check the support schemes in force with the official bodies.
The publisher cannot be held liable for any difference between the estimate shown and the actual cost or output of an installation.
When you enter an address, the calculator queries external geocoding and climate data services. What is sent to them is set out in detail in the privacy policy. None of your entries is sent to our own servers: the calculation runs entirely in your browser.
A wrong figure, a subsidy that has been withdrawn, an out-of-date tariff? Write to us: corrections are made quickly, and the date the sources were checked is shown at the foot of every page.
Privacy policy – what is collected, and what is not
This site has no accounts, no sign-up and no contact form. It sets no advertising cookies and sells nothing to anyone. Here are the details, without the jargon.
Only two features call external services, and only if you use them. In both cases your IP address is visible to the service called, as it is for any web request.
| Service | When | What is sent |
|---|---|---|
| Photon (Komoot) | You type an address into the location field. | The text you typed and the code of the country selected, to obtain a list of places. Nothing else. |
| Open-Meteo | You pick a place from the list. | The rounded latitude and longitude of the place, to retrieve the measured solar irradiation. |
| NASA POWER | The same, only if Open-Meteo does not respond. | The latitude and longitude, for the fallback monthly climatology. |
These calls rest on legitimate interest (GDPR, Article 6(1)(f)): they are strictly necessary to deliver the service you ask for by typing an address, and are limited to that request. You can use the whole calculator without ever entering an address — it will then use the national average.
This site sets no cookies. It writes a single entry in your browser's session storage, to remember that you closed the suggestion to change language. It disappears when you close the tab and is sent nowhere.
Like any site, the host keeps technical logs — IP address, page requested, timestamp — to keep the service running and secure. They are not used to profile you and are purged under the host's own policy.
The GDPR gives you rights of access, rectification, erasure, objection and portability. As we keep no data about you, there is in practice nothing to erase on our side; for the hosting logs, write to us and we will pass the request on. You may at any time lodge a complaint with the data protection authority of your country.
Any change to this policy will be dated at the foot of the page. For any question, the contact address is given in the legal notice.