How many solar panels to produce 30 kWh per day?
20 panels of 400 W, a 7.8 kW system on 414 sq ft of roof, to generate 30 kWh a day at 4.5 peak sun hours and 14% losses: 30 / (4.5 × 0.86) = 7.75 kW. In a 3.5-hour place it is 25 panels (10 kW), in a 5.5-hour place 16 (6.3 kW); in Texas 17, in London 26. 30 kWh a day is 913 kWh a month or 10,950 kWh a year, about what the average US home buys (29.6 kWh a day, EIA). The tables below run 5 to 50 kWh a day, then 30 kWh a day in every US state and UK city.
Open the solar panel calculator
How many panels for 5 to 50 kWh a day?
System kW = daily kWh / (peak sun hours × 0.86); panels = kW × 1,000 / 400, rounded up; roof area = panels × 1.922 m² (20.7 sq ft), the Trina Vertex panel the tool uses. Peak sun hours are the kWh/m² a day that reach the panel: 3.5 is a cloudy state or a sunny UK city, 4.5 is the middle of the US, 5.5 is the Southwest.
| kWh a day | 3.5 sun hours | 4.5 sun hours | 5.5 sun hours |
|---|---|---|---|
| 5 | 1.7 kW, 5 panels, 103 sq ft | 1.3 kW, 4 panels, 82.8 sq ft | 1.1 kW, 3 panels, 62.1 sq ft |
| 10 | 3.3 kW, 9 panels, 186 sq ft | 2.6 kW, 7 panels, 145 sq ft | 2.1 kW, 6 panels, 124 sq ft |
| 15 | 5 kW, 13 panels, 269 sq ft | 3.9 kW, 10 panels, 207 sq ft | 3.2 kW, 8 panels, 166 sq ft |
| 20 | 6.6 kW, 17 panels, 352 sq ft | 5.2 kW, 13 panels, 269 sq ft | 4.2 kW, 11 panels, 228 sq ft |
| 25 | 8.3 kW, 21 panels, 434 sq ft | 6.5 kW, 17 panels, 352 sq ft | 5.3 kW, 14 panels, 290 sq ft |
| 30 | 10 kW, 25 panels, 517 sq ft | 7.8 kW, 20 panels, 414 sq ft | 6.3 kW, 16 panels, 331 sq ft |
| 40 | 13.3 kW, 34 panels, 703 sq ft | 10.3 kW, 26 panels, 538 sq ft | 8.5 kW, 22 panels, 455 sq ft |
| 50 | 16.6 kW, 42 panels, 869 sq ft | 12.9 kW, 33 panels, 683 sq ft | 10.6 kW, 27 panels, 559 sq ft |
How many panels for 30 kWh a day in each US state?
Peak sun hours by state from NREL data (Unbound Solar table). Arizona needs 14 panels for 30 kWh a day, Alaska 30: the target is the same, the sun is not. For another daily figure scale the kW column; the panel calculator does it for any state with the roof area in sq ft.
| State | Sun hours | System size | Panels | Roof area |
|---|---|---|---|---|
| Alabama | 4.6 | 7.6 kW | 19 | 393 sq ft |
| Alaska | 3 | 11.6 kW | 30 | 621 sq ft |
| Arizona | 6.5 | 5.4 kW | 14 | 290 sq ft |
| Arkansas | 4.5 | 7.8 kW | 20 | 414 sq ft |
| California | 5.6 | 6.2 kW | 16 | 331 sq ft |
| Colorado | 5.5 | 6.3 kW | 16 | 331 sq ft |
| Connecticut | 4.2 | 8.3 kW | 21 | 434 sq ft |
| Delaware | 4.4 | 7.9 kW | 20 | 414 sq ft |
| District of Columbia | 4.4 | 7.9 kW | 20 | 414 sq ft |
| Florida | 5.3 | 6.6 kW | 17 | 352 sq ft |
| Georgia | 4.8 | 7.3 kW | 19 | 393 sq ft |
| Hawaii | 5.8 | 6 kW | 16 | 331 sq ft |
| Idaho | 4.9 | 7.1 kW | 18 | 372 sq ft |
| Illinois | 4.3 | 8.1 kW | 21 | 434 sq ft |
| Indiana | 4.2 | 8.3 kW | 21 | 434 sq ft |
| Iowa | 4.4 | 7.9 kW | 20 | 414 sq ft |
| Kansas | 5 | 7 kW | 18 | 372 sq ft |
| Kentucky | 4.3 | 8.1 kW | 21 | 434 sq ft |
| Louisiana | 4.7 | 7.4 kW | 19 | 393 sq ft |
| Maine | 4.2 | 8.3 kW | 21 | 434 sq ft |
| Maryland | 4.4 | 7.9 kW | 20 | 414 sq ft |
| Massachusetts | 4.2 | 8.3 kW | 21 | 434 sq ft |
| Michigan | 4 | 8.7 kW | 22 | 455 sq ft |
| Minnesota | 4.3 | 8.1 kW | 21 | 434 sq ft |
| Mississippi | 4.6 | 7.6 kW | 19 | 393 sq ft |
| Missouri | 4.6 | 7.6 kW | 19 | 393 sq ft |
| Montana | 4.7 | 7.4 kW | 19 | 393 sq ft |
| Nebraska | 4.8 | 7.3 kW | 19 | 393 sq ft |
| Nevada | 6.4 | 5.5 kW | 14 | 290 sq ft |
| New Hampshire | 4.2 | 8.3 kW | 21 | 434 sq ft |
| New Jersey | 4.3 | 8.1 kW | 21 | 434 sq ft |
| New Mexico | 6.5 | 5.4 kW | 14 | 290 sq ft |
| New York | 4 | 8.7 kW | 22 | 455 sq ft |
| North Carolina | 4.7 | 7.4 kW | 19 | 393 sq ft |
| North Dakota | 4.5 | 7.8 kW | 20 | 414 sq ft |
| Ohio | 4.1 | 8.5 kW | 22 | 455 sq ft |
| Oklahoma | 5.1 | 6.8 kW | 18 | 372 sq ft |
| Oregon | 4.2 | 8.3 kW | 21 | 434 sq ft |
| Pennsylvania | 4.1 | 8.5 kW | 22 | 455 sq ft |
| Rhode Island | 4.2 | 8.3 kW | 21 | 434 sq ft |
| South Carolina | 4.8 | 7.3 kW | 19 | 393 sq ft |
| South Dakota | 4.7 | 7.4 kW | 19 | 393 sq ft |
| Tennessee | 4.4 | 7.9 kW | 20 | 414 sq ft |
| Texas | 5.3 | 6.6 kW | 17 | 352 sq ft |
| Utah | 5.5 | 6.3 kW | 16 | 331 sq ft |
| Vermont | 4 | 8.7 kW | 22 | 455 sq ft |
| Virginia | 4.5 | 7.8 kW | 20 | 414 sq ft |
| Washington | 3.8 | 9.2 kW | 23 | 476 sq ft |
| West Virginia | 4.1 | 8.5 kW | 22 | 455 sq ft |
| Wisconsin | 4.2 | 8.3 kW | 21 | 434 sq ft |
| Wyoming | 5.2 | 6.7 kW | 17 | 352 sq ft |
How many panels for 30 kWh a day in the UK?
Sun hours are PVGIS daily irradiation at the optimal tilt (2005-2020), yearly average. 30 kWh a day takes 26 panels in London and 31 in Glasgow, and the winter gap is wider than the yearly figure suggests: the kWh-per-panel guide shows one panel making 3.3 times as much in June as in December in London.
| City | Sun hours | System size | Panels | Roof area |
|---|---|---|---|---|
| London | 3.48 | 10 kW | 26 | 50 m² |
| Brighton (South East) | 3.9 | 8.9 kW | 23 | 44.2 m² |
| Plymouth (South West) | 3.7 | 9.4 kW | 24 | 46.1 m² |
| Cardiff (Wales) | 3.47 | 10.1 kW | 26 | 50 m² |
| Birmingham (West Midlands) | 3.27 | 10.7 kW | 27 | 51.9 m² |
| Nottingham (East Midlands) | 3.3 | 10.6 kW | 27 | 51.9 m² |
| Norwich (East of England) | 3.49 | 10 kW | 25 | 48.1 m² |
| Manchester (North West) | 3 | 11.6 kW | 30 | 57.7 m² |
| Leeds (Yorkshire) | 3.2 | 10.9 kW | 28 | 53.8 m² |
| Newcastle (North East) | 3.18 | 11 kW | 28 | 53.8 m² |
| Edinburgh (Scotland) | 3.07 | 11.4 kW | 29 | 55.7 m² |
| Glasgow (Scotland) | 2.88 | 12.1 kW | 31 | 59.6 m² |
| Aberdeen (Scotland) | 2.98 | 11.7 kW | 30 | 57.7 m² |
| Belfast (Northern Ireland) | 3.09 | 11.3 kW | 29 | 55.7 m² |
What the tables leave out
- Seasons: 30 kWh a day is the yearly average of the array, not a floor. On a grid-tied system the summer surplus is exported and the winter shortfall is bought; off grid you size for the worst month and add a battery, which this page does not cover.
- Orientation, tilt and shade: the sun hours assume a south-facing array at a good tilt. An east or west roof gives 15-20% less (Energy Saving Trust); raise the losses in the calculator for shade.
- Rounding: the panel count rounds up, so the installed size is a little above the kW figure and makes a little more than the target: 20 panels at 4.5 hours make 31 kWh a day, not 30.
- Monthly figures: if the bill says kWh a month, the 2,000 kWh a month guide runs 500 to 3,000 kWh a month in the same three columns.
- The other direction: the output calculator shows what 1 kW, 4 kW and 10 kW produce per day, month and year in London and Texas, and takes any size for any state or UK city.
Sources
US sun hours: Unbound Solar, "Peak Sun Hours by US State", table built from NREL's PVWatts data; "A peak sun hour is one hour of sunlight at an average intensity of 1,000 watts per square meter". UK sun hours: European Commission Joint Research Centre, PVGIS 5.2, PVcalc for the city's coordinates at the optimal slope and azimuth. Panel: A 400 W panel is the middle of the Trina Vertex TSM-DE09 range and the common residential class in 2026; Trina Solar, Vertex TSM-DE09 data sheet, product range 390-405 W. Losses: NREL, PVWatts Version 5 Manual, section 11 System Losses, Table 6. Average US home use: U.S. Energy Information Administration, FAQ "How much electricity does an American home use?". UK household sizes: Ofgem, "Review of typical domestic consumption values: decision", Table 1, electricity Profile Class 1, 2026 TDCV. Installed cost: EnergySage, "How much do solar panels cost?". All read 2026-09-20; the full text of each source, with links, is under the panel and payback calculators.
Frequently asked questions
- How many solar panels do I need to generate 30 kWh per day?
- 20 panels of 400 W at 4.5 peak sun hours (7.75 kW needed, 8 kW installed), 25 at 3.5 hours, 16 at 5.5. Divide the daily kWh by the sun hours and by 0.86 to get the kW, then divide the watts by 400 and round up. The 20 panels actually make 31 kWh a day because the count rounds up.
- How many solar panels to generate 30 kWh per day in the UK?
- 26 panels of 400 W in London: 30 / (3.48 PVGIS sun hours × 0.86) = 10.02 kW, rounded up to 10.4 kWp. In Brighton (3.9 sun hours) it is 23 panels, in Glasgow (2.88) 31. At £1,690 per kWp (derived from the Energy Saving Trust's "around £7,600" for a typical 4.5 kWp system, August 2026) the London array costs about £17,576 installed. The UK table above has all 14 cities.
- Is a 30 kWh per day solar system 8 kW or 10 kW?
- Either, depending on the sun. At 4.5 peak sun hours it needs 7.75 kW, so 20 panels of 400 W give 8 kW installed, which makes 31 kWh a day. At 3.5 hours it needs 9.97 kW: 25 panels, 10 kW installed, 30.1 kWh a day. At 5.5 hours 6.34 kW: 16 panels, 6.4 kW, 30.3 kWh a day. Compare quotes on the kW figure; the panel count follows from the wattage offered.
- How much does a solar system that makes 30 kWh a day cost?
- About $20,800 before incentives at 4.5 sun hours: 20 panels × 400 W = 8 kW, × $2.60 per watt (EnergySage US average, June 2026). The federal 30% credit ended for systems placed in service after 31 December 2025. More sun hours mean fewer panels and a lower price; the payback calculator takes your own quote and rate.
- How many kW of solar do I need for 30 kWh a day?
- 7.75 kW at 4.5 sun hours, 9.97 kW at 3.5 and 6.34 kW at 5.5. The kW figure is the one to compare quotes on; the panel count follows from the wattage the installer offers. A 30 kWh day is a yearly average: the array makes more than that in June and less in December.
- Is 30 kWh a day a lot for a house?
- It is the average US home: 899 kWh a month (EIA) is 29.6 kWh a day. In the UK it is a great deal: a medium Ofgem household uses 2,500 kWh a year, 6.8 kWh a day, and a high one 3,800 a year, 10.4 kWh a day; 30 kWh a day in the UK means a heat pump, an electric car or both.
- How many solar panels for 10 kWh, 20 kWh or 50 kWh a day?
- At 4.5 sun hours: 7 panels (2.58 kW) for 10 kWh a day, 13 (5.17 kW) for 20 and 33 (12.92 kW) for 50. The first table runs the three sun-hour columns for 5 to 50 kWh a day; the calculator takes any figure, in kWh a month, so multiply a daily figure by 30.42.
- How much does one 400 W panel make per day?
- 1.55 kWh at 4.5 sun hours (0.4 kW × 4.5 × 0.86), which is why 30 kWh takes 19.4 panels before rounding. The kWh-per-panel guide runs one panel at 3 to 6 sun hours and by state.
More guides
- How many solar panels for 2,000 kWh a month?
2,000 kWh a month is 65.8 kWh a day: 43 panels of 400 W (17.2 kW) at 4.5 sun hours, about $44,720 installed. Every US state and UK city.
- How many solar panels to power a house?
Panels for the average US home (EIA 899 kWh a month) from half to twice that use, every US state, and Ofgem's low, medium and high UK homes in four cities.
- How many solar panels for 1,000 kWh a month?
1,000 kWh a month is 32.9 kWh a day: 8.5 kW of solar, 22 panels of 400 W, at 4.5 sun hours. Sizes at 3 to 6 sun hours, every US state and UK city.
- How many solar panels for 1,500 kWh a month?
1,500 kWh a month is 49.3 kWh a day: 12.7 kW of solar, 32 panels of 400 W, at 4.5 sun hours. Sizes at 3 to 6 sun hours, every US state and UK city.
Last updated 2026-10-03. Estimates from published averages (NREL, EIA, Ofgem, industry cost surveys), each with its source and date: an installer's site survey and shading analysis replace them. Not financial advice.