Solar System Calculator — Size Panels, Battery & Inverter (Free)
Size your complete solar system — panels, battery, inverter, and controller from your appliance list.
Free solar sizing tool
Solar System Calculator
Follow the sun from your appliances to a complete system — panels, batteries, inverter, charge controller and cost.
Build your daily load
Add what you run — or start from your electricity bill.
| Appliance | Watts | Qty | Hrs/day | Backup | kWh/day |
|---|
Size your solar panels
Sun hours vary by location. Pick your region, then choose a panel size.
Size your battery bank
The part most calculators skip: the same backup, compared across four battery chemistries.
“Usable depth” is why lithium needs fewer batteries: lead-acid only safely gives ~50% of its rating, lithium 80–90%.
Inverter & charge controller
The inverter must carry everything running at once; the controller must carry your full array.
Your complete system
Everything sized — with upfront and 10-year cost, side by side. Prices are editable for your local market.
Adjust prices & currency
Estimates for planning only. Real systems depend on shading, roof, wiring runs and local equipment. Confirm with a qualified installer before buying.
Frequently Asked Questions
How do I calculate how many solar panels I need for my house?
Add up the wattage of every appliance you run and how many hours each runs per day to get your daily kWh consumption. Divide that by the peak sun hours in your location, then divide by the wattage of the panel you plan to use. The calculator above does this automatically — enter your appliances and it outputs the exact panel count, inverter size, battery bank, and charge controller specifications.
What size solar system do I need for 1,000 kWh per month?
To produce 1,000 kWh per month, you need roughly a 6 to 8 kW solar system depending on your location. In a 5-sun-hour region, a 6.7 kW system produces about 1,000 kWh monthly. In a 4-sun-hour region, you need approximately 8.3 kW. Enter your exact monthly consumption above and the calculator sizes the system for your specific location.
Can I run my whole house on solar panels?
Yes, but the system size depends on your total consumption. An average US home using 900 kWh per month needs a 6 to 7 kW system. A larger home using 2,000 kWh needs 13 to 15 kW. The calculator sizes a system for 100 percent offset by default — enter all your appliances and it tells you the exact panel count and battery capacity for full off-grid operation or grid backup.
How many solar panels do I need to run an air conditioner?
A 1-ton (12,000 BTU) air conditioner uses about 1,200 watts. Running it 8 hours per day consumes 9.6 kWh daily. At 5 peak sun hours, you need roughly 2,400 watts of panels (four 600W panels or six 400W panels) plus a 5 kVA inverter to handle the 3,600W startup surge. The calculator accounts for surge automatically when you add an AC to your appliance list.
Is a 6kW solar system enough for a family of 4?
For most families of 4, a 6 kW system covers 80 to 100 percent of electricity needs if total monthly consumption is under 900 kWh. If you run heavy loads like central air conditioning, an electric water heater, or an EV charger, you may need 8 to 12 kW. Enter your actual appliances in the calculator above for a precise answer rather than relying on averages.
Does the solar calculator work for commercial buildings?
Yes. The calculator handles any system size from a single panel to hundreds of kilowatts. Enter your commercial load in watts and hours, select your peak sun hours, and it outputs the panel array, inverter, and battery bank at any scale. For commercial systems, the cost per watt is typically lower (1.50 to 2.50 dollars) than residential. See our commercial solar installation guide for detailed pricing.
Does it account for cloudy days and shade?
The calculator uses peak sun hours, which already factor in average cloud cover for your region. A region listed at 5 peak sun hours does not have 5 hours of perfect sun — it has the equivalent of 5 hours of full-intensity sun averaged across all weather conditions throughout the year. For shading from trees or buildings, reduce the peak sun hours by 10 to 20 percent to compensate.
Is the solar calculator free to use?
Yes, completely free with no account required. Enter your appliances, get your results, and use the copy, save as PDF, or share buttons to keep your system specifications. The calculator runs entirely in your browser — no data is sent to any server.