Path-Q Solar

What should I compare when two solar quotes use different system sizes?

Answer

Compare expected annual production and its assumptions, not panel capacity alone. Review usable roof area, shading, orientation, equipment, degradation assumptions, export limits, included work, price, financing, warranties, and the portion of your consumption each system is expected to serve.

Key points

  • A larger system is not automatically better if it has lower-quality assumptions, greater shading, or low-value exports.
  • Compare production per installed capacity and the modeled production by month where available.
  • Check whether one quote includes batteries, service upgrades, roof work, monitoring, permits, or other items omitted from the other.

What it depends on

  • Historical electricity consumption
  • Roof orientation, tilt, shading, and usable area
  • Utility export arrangement
  • Panel and inverter specifications
  • System price, financing, and included scope

Risks and trade-offs

  • Oversizing can increase cost while producing exports with limited value.
  • Undersizing can leave future electricity needs uncovered and make expansion difficult.
  • Production estimates are forecasts, not guarantees, unless the contract provides specific performance protection.

Information you may need

  • Itemized equipment and scope for each quote
  • Annual and monthly production estimates
  • Recent electricity bills and expected future load
  • Export tariff and any system-size limits

Your next step

What to do next

Put both proposals into a side-by-side comparison using the same consumption and tariff assumptions, and ask each installer to explain every material difference.

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SQ00496