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Your Electricity Usage
Average monthly bill before solar
Check your bill or use 0.14 average
80% offsets most usage while keeping costs reasonable
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System Preferences
South-facing in N. hemisphere, North-facing in S. hemisphere
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Your Daily Power NeedsAdd each device you plan to run. The calculator tallies your total daily watt-hours.
| Device | Watts | Hrs/Day | Wh/Day |
|---|
Total: 0 Wh/day
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System Configuration☀
Peak Sun Hours by RegionAnnual averages. Your actual production depends on season, local weather, shading, and panel angle. Southern hemisphere: swap summer/winter expectations.
United States
6.5-7.5 Arizona, Nevada, SoCal desert
5.5-6.5 Texas, Florida, SoCal coast
4.5-5.5 Mid-Atlantic, Southeast, Colorado
4.0-5.0 Midwest, Arkansas, Tennessee
3.5-4.5 Northeast, Great Lakes, Oregon
3.0-4.0 Pacific NW, Alaska, upper Midwest
Australia & New Zealand
6.5-7.5 Northern Territory, inland QLD/WA
5.5-6.5 Perth, Brisbane, Adelaide, inland NSW
4.5-5.5 Sydney, Canberra, coastal QLD
3.5-4.5 Melbourne, Hobart, New Zealand
Europe
5.5-6.5 Southern Spain, Greece, Sicily, Cyprus
4.5-5.5 Portugal, southern France, Italy, Croatia
3.5-4.5 Northern France, Germany, Poland, Austria
2.5-3.5 UK, Ireland, Netherlands, Scandinavia
Canada
4.5-5.5 Southern Alberta, Saskatchewan prairies
3.5-4.5 Ontario, Quebec, southern BC
2.5-3.5 Coastal BC, Maritime provinces, northern
Central & South America
6.0-7.5 Mexico (Sonora, Baja), Atacama, NE Brazil
5.0-6.0 Central Mexico, Colombia, Argentina plains
4.0-5.0 Southern Brazil, Chile coast, Central America
Africa & Middle East
6.5-8.0 Sahara, Arabian Peninsula, Namibia
5.5-6.5 South Africa, East Africa, Morocco
4.5-5.5 Coastal West Africa, Israel, Turkey
Asia & Pacific
5.5-7.0 India (Rajasthan, Gujarat), Thailand
4.5-5.5 Central India, Philippines, Indonesia
3.5-4.5 Japan, South Korea, eastern China
Affiliate Disclosure: This calculator is free to use. Some product links on this page are affiliate links, which means we may earn a small commission if you purchase through them at no extra cost to you. This helps us keep this tool free and maintained. We only recommend products we'd use ourselves.
How This Calculator Works
This tool uses industry-standard formulas to size your solar system. Here's what goes into the math:
- Home Solar: Your monthly kWh usage is derived from your electric bill and rate. We divide by 30 for daily usage, factor in your sun hours and roof direction, then add a 20% system loss factor (wiring, inverter efficiency, dirt, temperature) to determine the total panel wattage needed.
- Van/RV Solar: Your total daily watt-hours determine everything. We factor in charge controller efficiency (MPPT: 85%, PWM: 75%), system losses, and battery depth of discharge (LiFePO4: 80%, AGM: 50%) to size your battery bank. Panel wattage accounts for real-world conditions, not lab ratings.
- Wire sizing follows NEC guidelines based on amperage and typical installation distances. International users should verify local wiring codes.
- All estimates are conservative. Real-world conditions vary. The sizing math is universal; product links point to US retailers. Consult a licensed electrician for home installations.