Free Tool — Gramowatt

What Size Solar System
Does Your Home Need?

Add the devices you wish to power with solar, how many hours you plan to use them, and this tool calculates the exact inverter, battery bank, and solar panel array your household requires — based on real engineering principles.

Step 1 — Your Appliances

How to fill this in: Select each appliance — its typical wattage will be filled in automatically. You can type a different wattage if your appliance label shows something else. Then split your daily usage into daytime hours (8am–6pm) and night-time hours (6pm–8am). Night-time hours determine your battery bank size because the sun is not generating power during that period.
Appliance Wattage Qty Day hrs
(8am–6pm)		 Night hrs
(6pm–8am)

Step 2 — Battery Preference

Lithium (LiFePO4): Higher upfront cost, lasts 8–12 years, 80–90% usable capacity, virtually zero maintenance.  |  Tubular/Gel: More affordable upfront, lasts 3–5 years, only 50% usable capacity. Tubular requires periodic distilled water top-up; Gel is sealed and maintenance-free.

Step 3 — Your Location (determines your practical effective sun hours)

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South: 1 – 3 peak sun hours. North: 2 – 4 peak sun hours.

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Shading reduces how much energy your panels can generate.

🔐 For professionals only — if you have site-specific measured data. All other users should leave this blank and trust the state default above.

🔐 For professionals only — enter a specific panel wattage e.g. 750W. All other users should leave blank and use the system's panel suggestions.

Step 4 — Energy Costs in Your Area (Required — used to calculate your recommended solar investment)

Why we ask this: We use your local petrol price and NEPA tariff to calculate exactly how much you should be willing to invest in a solar system — based on your expected consumption and current prices of alternative energy sources.

Enter the pump price of petrol at your nearest filling station today.

Check your prepaid meter or last NEPA bill for your tariff per unit (1 unit = 1 kWh).

Add your appliances in Step 1 and select your state in Step 3 to unlock

Solar Sizing Report
Gramowatt
gramowatt.com
Your Solar System Summary
Important: This calculator gives an accurate starting estimate based on your inputs. Final specifications should be confirmed by a certified installer who will conduct a full site assessment. Contact Gramowatt for a free, personalised quote.

If the entry budget above is beyond your current reach — reduce appliance quantities or cut daily hours to bring costs down to your comfort level, then recalculate.

Tap the button above → choose Save as PDF or Share to send via WhatsApp, Gmail, etc.

Calculated by Gramowatt — Nigeria's Trusted Power Solution Provider.
Get an Accurate Installation Quote on WhatsApp →  |  View solar packages →

Gramowatt
Nigeria's Trusted Power Solution Provider  |  gramowatt.com
This report is an engineering estimate. Final specifications must be confirmed by a certified installer.
Get a free quote: gramowatt.com/solar-quote
— calculations
Made with this Calculator Join Nigerians making smarter energy decisions with Gramowatt