Solar vs Generator Cost Calculator

Compare generator fuel and maintenance against a solar and battery kit over one year and five years. Use local prices, outages, finance terms, and grid spend to decide which backup path is cheaper and more reliable.

Editable assumptions

Scenario inputs

Enter the backup power pattern you actually face. Defaults are only a starter scenario.

Average hours per day that backup power must cover.
Appliances you expect to run during outages.
Use the tariff or prepaid unit rate from your bill.

Your inputs are calculated in this browser and can be copied or exported as CSV.

Cost comparison result

Enter assumptions and compare the 1-year and 5-year cost of backup power.

Ready to compare
1-year generator - Monthly fuel plus maintenance
1-year solar - Deposit, payment, and maintenance
5-year difference - Positive means solar saves money
Payback month - Monthly cashflow during finance term

Generator path

Monthly fuel cost-
Monthly maintenance-
5-year total-
Emissions and noise-

Solar and battery path

Monthly payment-
Monthly maintenance-
5-year total-
Battery coverage-

Recommendation

Complete the inputs to see whether solar, generator, or a hybrid backup plan is stronger for this scenario.

  • Confirm fuel and tariff prices from current receipts or bills.
  • Ask installer and generator supplier for written maintenance assumptions.
  • Check battery warranty, depth of discharge, ventilation, and load limits before purchase.

Methodology

The calculation method turns your outage pattern into monthly backup energy, then compares generator operating cost with solar finance cost.

  1. Backup kWh/month = critical load kW x daily outage hours x 30.4375.
  2. Generator monthly cost = litres/hour x outage hours x days x fuel price + generator maintenance.
  3. Solar monthly cost = financed balance divided by term + maintenance rate x kit cost / 12.
  4. Payback is the first month where cumulative solar cost is less than or equal to cumulative generator cost.

Assumptions and sources

Use this source checklist before committing money. The tool is based on user-entered assumptions, not a live official price feed.

  • Fuel price: latest receipt or station board near your business or home.
  • Grid cost: utility bill, prepaid statement, or published tariff from the electricity authority.
  • Solar price: installer quote that separates panels, inverter, battery, installation, warranty, and finance fees.
  • Official context: verify safety and tariff changes with your national utility regulator, energy commission, or ministry.

Disclaimer

This is an estimate only for planning. It does not replace a licensed electrical design, installer site survey, generator manual, lender quote, insurance review, or official utility guidance.

  • Fuel quality, generator load factor, battery degradation, taxes, delivery, and installation quality can change the result.
  • Do not run generators indoors or in enclosed spaces. Confirm ventilation, earthing, wiring, and battery safety locally.
  • Last reviewed and dated assumptions: 16 May 2026.
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Plan the full backup power decision

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