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SolarEvaluator

Solar System Calculator

Free solar sizing tool

Solar System Calculator

Follow the sun from your appliances to a complete system — panels, batteries, inverter, charge controller and cost.

Step 1 · Sunrise

Build your daily load

Add what you run — or start from your electricity bill.

We divide by 30 to get your daily energy — you can still add heavy appliances below for accurate inverter sizing.
Appliance Watts Qty Hrs/day Backup kWh/day
Total energy per day 0.0 kWh
Peak (connected) load 0 W
Step 2 · Morning

Size your solar panels

Sun hours vary by location. Pick your region, then choose a panel size.

Covers wiring, heat, dust and inverter losses. 20% is a safe default.
Panels needed 0
Array size 0.0 kW
Roof area needed 0 0 sq ft
⚡ Units generatedkWh from your sunlight
Per panel / day0.0 units
Whole array / day0.0 units
Per month0 units
Step 3 · Noon

Size your battery bank

The part most calculators skip: the same backup, compared across four battery chemistries.

8 hours of backup — typical overnight / load-shedding cover
Battery should cover:
Sizes on the appliances you ticked “Backup” in Step 1 — how real grid-backup systems are specified.

“Usable depth” is why lithium needs fewer batteries: lead-acid only safely gives ~50% of its rating, lithium 80–90%.

🔋 Units stored per battery12V × 200Ah
Rated capacity0.0 units
Usable (lead-acid)0.0 units
Usable (LiFePO4)0.0 units
Step 4 · Afternoon

Inverter & charge controller

The inverter must carry everything running at once; the controller must carry your full array.

25–35% suits mostly electronics, lights and light appliances.
Continuous load 0 W everything running together
Surge peak (motor start) 0 W worst-case startup spike
Recommended inverter 0.0 kVA
Charge controller (MPPT) 0 A

Step 5 · Sunset

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.