Fotovol

Solar panel calculator

How many kW you need, what it costs, when it pays back

Calculate in 30 seconds how many kW of solar panels you need on your roof, the estimated cost in lei, and the value after the Casa Verde subsidy. Start from your monthly consumption (on your electricity bill) and adjust for EVs, heat pump, or extra AC units. For a contractual figure request a quote or read the help guide.

Advanced calculator

Advanced calculator — detailed sizing

Look on your electricity bill.

Panel brand (preference)

These numbers are indicative only. Only an installer visiting your home can tell you exactly how many panels will fit and how they'll be positioned on your roof.

See how panels would fit on your roof

Enter dimensions and watch panels pack onto a top-down preview, with compass + tilt + occupancy controls.

Brand directory by tier — what you will be looking at

Panels

Inverters

Batteries

How the solar panel calculator works

The calculator gives you three numbers from your input: recommended system capacity in kWp, estimated total cost in lei, and what portion of that cost the Casa Verde subsidy could cover. It starts from your average monthly consumption in kWh (on your electricity bill) and adjusts for electric vehicles, heat pumps, and extra AC units. The output also reflects your panel-tier preference (top, mid, low) and an optional storage battery.

How many kW of solar panels do you need

The simple rule: divide your annual consumption (in kWh, from your bill) by roughly 1,200 and you get an indicative capacity in kWp. A home using 4,000 kWh/year lands at ~3.5 kWp, one using 6,000 kWh/year at ~5 kWp, and an EV or heat pump pushes you towards 8–10 kWp. Mind the connection limit: on a single-phase connection you can typically install 6–9 kW depending on the main breaker — beyond that you need a three-phase upgrade. The calculator above runs exactly this computation from your monthly bill and adds the corrections for large consumers.

How much a solar system produces in Romania

One installed kWp yields between 1,150 and 1,400 kWh per year, depending on county, orientation and tilt. A south-facing 5 kWp system therefore generates roughly 6,000–6,500 kWh/year: around 700–800 kWh in a good summer month and 150–250 kWh in December–January. The monthly distribution matters more than the annual total when you size a battery or estimate the winter bill — see how many kWh 1 kWp produces, month by month, by region.

Orientation and tilt: how much they change the numbers

South at 30–35° tilt is the theoretical optimum, but deviations cost less than most people think: east–west typically loses 10–15% of annual production, and any tilt between 20° and 45° shifts the result by only a few percent. An east–west roof even has a practical advantage: production spread across morning and evening, when you actually consume. Do not give up on a “badly oriented” roof before running the numbers — enter your consumption in the calculator and read our orientation and tilt guide.

Assumptions behind the numbers

The calculation uses an average yearly production of ~1,250 kWh/kWp for south-facing systems, varying between 1,150 and 1,400 kWh/kWp depending on the county and roof tilt. The electricity price defaults to a representative Romanian residential tariff for 2026; if your tariff is different, the payback period scales linearly. The maximum subsidy considered is 30,000 RON, the cap of the latest AFM Casa Verde Fotovoltaice edition for panels (2024, up to 90% of cost, with a minimum own contribution of 3,000 lei). The 2026 edition of the program is announced with a focus on storage batteries, and the funding guide for panels has not yet been published. Cost ranges use mid-market prices for residential kits and already account for the reduced VAT regime applied to home installations. Panel degradation (~0.5%/year) and maintenance fall outside the calculator's scope.

From estimate to real decision

The number is a sanity-check anchor for installer conversations, not a binding price. Use it to compare 2–3 quotes: if one is 30% above the estimate, ask why; if it's lower, check the equipment (panel tier, inverter brand, battery type). A real number needs an on-site assessment of orientation, tilt, electrical panel, and distance to the meter. Read more in how much a solar system costs and how Casa Verde works, or request a personalized quote. To estimate how many panels fit on your roof, use the positioning estimator.

Frequently asked questions

How much do I save with solar panels?
Depends on your consumption and tariff. A typical Romanian home with 4,000–6,000 kWh/year consumption saves 4,000–7,000 RON/year at a ~1.3 RON/kWh tariff. Enter your real monthly kWh in the calculator for a personalized number.
How long until a solar system pays back?
Without subsidy: 7–10 years; with Casa Verde: 4–6 years. Varies with tariff, consumption, and system size. If the tariff rises, the payback period shortens automatically.
Does the calculator include the Casa Verde subsidy?
Yes, if you tick the option, the calculator deducts the 30,000 RON cap from the total cost — the cap of the latest AFM Casa Verde Fotovoltaice edition for panels. The subsidy isn't automatic — you must apply separately at AFM when the program opens. The 2026 edition is announced with a focus on storage batteries, and the guide for panels has not yet been published. See the Casa Verde guide for details.
How does the electricity price affect payback?
Directly and linearly. At constant consumption, a 20% tariff increase boosts annual production value by 20% and shortens payback proportionally. If tariffs fall (unlikely long-term in Romania), payback lengthens.
Can I sell excess energy?
Yes, via prosumer status. In Romania's current model, excess fed into the grid offsets consumption at the same tariff (simplified net metering) over a year. The calculator assumes this model — for details see what it means to be a prosumer and check your supplier's offer.
How many kW do I need for a typical house?
For 4,000–6,000 kWh/year of consumption, the right capacity is usually 3.5–5 kWp. Add 2–3 kWp for an EV and 3–4 kWp for a heat pump. On a single-phase connection the practical limit is 6–9 kW; beyond that you need three-phase.
How much does 1 kWp of solar panels produce per year?
In Romania, between 1,150 and 1,400 kWh/year, depending on county, orientation and tilt. The south and Dobrogea sit at the top of the range, northern Transylvania and mountain areas at the bottom.
Does roof orientation matter in the calculation?
Yes, but less than most people think: versus ideal south, an east–west roof typically loses 10–15% of annual production, and tilts between 20° and 45° give similar results. The calculator assumes south orientation — for east–west, reduce the result by 10–15%.
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