9 × 430 W panels (3.87 kWp) produce about 4,584 kWh a year, 102% of your 4,500 kWh. They need about 18 m² of your 40 m² roof.
Panels needed
9× 430 W
to cover 100% of 4,500 kWh/yr
System size
3.87kWp
exact need 3.8 kWp
Annual production
4,584kWh
12.6 kWh per day on average
Share of use covered
102%
Specific yield
1,185kWh/kWp
NASA climate (default site)
Roof area needed
18m²
fits, with room for up to 19 panels
Max system on your roof
8.17kWp
19 panels → 9,678 kWh/yr
Months short of demand
5/ 12
worst month covers 41%
Estimated installed cost
€4,257
1.1 €/Wp
Year-1 savings
€711
simple payback about 6 years
Same target with other panel sizes
| Panel class | Panels | kWp | Roof m² | Your roof |
|---|---|---|---|---|
| 300 W polycrystalline · 1.65 × 0.99 m | 13 | 3.9 | 22 | fits |
| 400 W mono PERC · 1.72 × 1.13 m | 10 | 4 | 20 | fits |
| 430 W N-type TOPCon · 1.72 × 1.13 m | 9 | 3.87 | 18 | fits |
| 450 W TOPCon · 1.76 × 1.13 m | 9 | 4.05 | 19 | fits |
| 490 W TOPCon · 1.9 × 1.13 m | 8 | 3.92 | 18 | fits |
| 550 W mono PERC · 2.28 × 1.13 m | 7 | 3.85 | 19 | fits |
| 620 W TOPCon · 2.38 × 1.13 m | 7 | 4.34 | 20 | fits |
| 700 W HJT bifacial · 2.38 × 1.3 m | 6 | 4.2 | 19 | fits |
Monthly balance
| Month | Solar (kWh) | Use (kWh) | Coverage |
|---|---|---|---|
| Jan | 210 | 440 | 48% |
| Feb | 272 | 374 | 73% |
| Mar | 394 | 391 | 101% |
| Apr | 460 | 352 | 131% |
| May | 513 | 352 | 146% |
| Jun | 506 | 334 | 152% |
| Jul | 537 | 352 | 152% |
| Aug | 524 | 352 | 149% |
| Sep | 430 | 345 | 125% |
| Oct | 346 | 375 | 92% |
| Nov | 212 | 393 | 54% |
| Dec | 180 | 440 | 41% |
- Sunshine: NASA POWER long-term monthly climate at 44.43, 26.1, transposed to 32° tilt and 180° azimuth, with a 14% loss budget and the temperature behaviour of N-type TOPCon modules.
- Coverage is an annual energy balance. Without a battery a typical home uses only 25–45% of solar output directly. The rest is exported, so its value depends on your net-metering or feed-in rules.
- Roof area includes 4% for clamps and gaps. For an exact layout with setbacks and portrait/landscape rows, use the solar roof area calculator.
- Pre-rendered with the embedded NASA climate for Bucharest; your browser loads data for the location you choose.