Free calculators for panel size, battery capacity, inverters, ROI and financing — tuned to your country's electricity rates and sun hours. No email wall, no signup, just numbers you can trust.
Every tool asks only for what actually changes your answer. Everything else is pre-filled with a sensible, editable default for your country.
Estimate system size, panel count and roof area from your monthly bill.
📈 SizingHow much electricity will your system produce — full monthly breakdown.
🔋 StorageFind the right battery bank in kWh for backup or off-grid autonomy.
⚡ StorageMatch inverter capacity (kVA) to your appliances and surge loads.
📈 MoneySee payback period, 25-year savings and annualised return on your system.
🏦 MoneyCompare monthly loan payments against your current electricity bill.
🏔️ SizingSize panels, battery and backup days-of-autonomy for a cabin or full off-grid home.
💰 MoneySee your monthly and lifetime savings from switching to solar, in plain numbers.
⏱️ MoneyThe fastest way to answer "how many years until solar pays for itself?"
🔌 MoneyModel your grid bill after export credits under your utility's net metering rules.
🚗 StorageFind the extra solar and charger size you need once you add an EV.
📐 SizingFind your optimal panel tilt angle and how much a non-ideal angle costs you.
🌤️ SizingCheck average daily sun hours for your country by month — feeds every other tool.
🔧 SizingCorrect wire gauge for your run length and current, in mm² and AWG.
🌳 SizingSee how much a tree, chimney or nearby building is really costing you in production.
⏳ StoragePick your appliances and see exactly how many hours your battery will last.
🎛️ StorageRight MPPT amp rating for your array power and battery voltage.
⛽ StorageSize a backup generator and estimate daily fuel use for gas, diesel or propane.
⚖️ MoneyCompare cash, loan, lease and PPA side by side to see which really saves more.
🧾 MoneyFull price breakdown — equipment, labor, permits and tax — not just $/W.
📋 MoneyYour net cost after incentives — updated for the expired 2026 US federal credit.
📏 SizingHow many panels actually fit on your roof, from your usable area.
🔌 SizingHow many extra panels your AC, pool pump or water heater really needs.
🧮 SizingNo solar needed — estimate your monthly bill from your actual appliances.
⏰ StorageDoes a battery pay for itself just by shifting peak vs. off-peak usage?
💵 StorageWhat a home battery actually costs — equipment vs. installation, broken out.
📉 StorageHow many kW a battery can shave off your peak demand, and what it's worth.
We'd rather ship 6 tools that give a genuinely correct answer than 100 that guess. Here's what's live and what's next — the full build list is on the sitemap.
Row spacing to avoid winter inter-row shading on ground-mounted arrays.
Correct overcurrent protection sizing for your array and battery wiring.
Estimate how much solar could add to your home's resale value.
Pick your country and every field pre-fills with local electricity rates, average sun hours and typical install costs — sourced and clearly labelled, always editable.
Most "free" solar calculators exist to collect your phone number for installers. Ours don't — results show instantly, no account, no forced quote request.
Electricity rates, net metering policy and typical install cost can swing your payback period by years depending on where you live. Pick your state for a snapshot, or use the state selector inside any calculator.