Path-Q Solar

How should I calculate the payback period for a cash-purchased solar system?

Answer

Divide net upfront cost by first-year net savings only as a simple estimate; a better calculation models annual production, bill changes, degradation, maintenance, replacement, taxes, and residual value over time.

Key points

  • Net cost must include all installed costs and verified incentives.
  • Savings should distinguish avoided purchases from exports.
  • Simple payback ignores the time value of money.

What it depends on

  • Net project cost
  • Annual savings
  • Future costs and production

Risks and trade-offs

  • Simple payback can overstate performance.
  • It does not measure returns after payback or compare alternative investments.

Information you may need

  • Final installed price
  • Bill and production model
  • Incentives and recurring costs

Your next step

What to do next

Calculate both simple payback and a discounted cash-flow case using conservative assumptions.

Path-Q

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Some details may depend on your location, installer, utility, incentives, regulations, or specific property.

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