Balcony solar in Longmont
800 W of panels on a south-facing balcony railing in Longmont produce about 840 kWh a year and save about $68.
Output by orientation and mounting
Yearly output with 800 W of panels and the inverter limited to 800 W.
| Panels face | On the railing (vertical) | Tilted at 30° |
|---|---|---|
| East | 630 kWh | 1,010 kWh |
| South-east | 830 kWh | 1,180 kWh |
| South | 840 kWh | 1,220 kWh |
| South-west | 740 kWh | 1,120 kWh |
| West | 530 kWh | 920 kWh |
Output by month
Show as a table
| Month | Railing (vertical) | Tilted at 30° |
|---|---|---|
| Jan | 87 kWh | 80 kWh |
| Feb | 79 kWh | 84 kWh |
| Mar | 87 kWh | 120 kWh |
| Apr | 64 kWh | 120 kWh |
| May | 49 kWh | 110 kWh |
| Jun | 42 kWh | 120 kWh |
| Jul | 45 kWh | 120 kWh |
| Aug | 56 kWh | 110 kWh |
| Sep | 67 kWh | 99 kWh |
| Oct | 89 kWh | 100 kWh |
| Nov | 85 kWh | 81 kWh |
| Dec | 91 kWh | 80 kWh |
Savings and payback
At $0.1656 per kWh you save about $68 in the first year. A kit costing $1,300 pays back in about 19.0 years.
- Electricity price: $0.1656 per kWh (U.S. Energy Information Administration, 2025-09..2026-08). Source
- Assumes a constant base load of 150 W, so 49% of the output is used at home.
- Power sent to the grid is not paid for.
Rules
Colorado
In effect since August 12, 2026
Up to 1,920 W of inverter output per home.
- Labeled and listed by a nationally recognized testing laboratory and cannot energize the grid during a power outage. From January 1, 2027, kits over 391 W may only be sold if UL labeled and listed.
- Your utility may ask you to register the kit.
Last verified: October 31, 2026
Nearby cities
- Boulder 820 kWh a year · 14 mi
- Thornton 880 kWh a year · 22 mi
- Westminster 860 kWh a year · 23 mi
- Arvada 840 kWh a year · 25 mi
- Greeley 880 kWh a year · 27 mi
Data sources
- Solar data: PVGIS-NSRDB, PVGIS 5.2, 2011–2015.
- Electricity price: U.S. Energy Information Administration, 2025-09..2026-08.
- Last verified: October 31, 2026
- How we calculate