Path-Q Solar

How can different export rates change the value of a larger solar system?

Answer

A larger system is most valuable when its additional generation offsets your own high-value consumption. Once generation exceeds on-site use, the value of the extra output depends on the export rate, which may be lower, capped, time-dependent, or subject to limits. Therefore, the marginal value of added capacity can fall sharply.

Key points

  • Calculate the value of each additional unit of generation after accounting for self-consumption.
  • Use hourly or monthly load and production where export rates vary by time.
  • Include fixed charges, demand charges, export caps, and battery effects.
  • Compare the incremental cost and incremental savings of the larger system, not just total savings.

What it depends on

  • On-site load profile
  • System size and production profile
  • Export compensation and limits
  • Battery dispatch
  • Utility tariff

Risks and trade-offs

  • Oversizing can create low-value exports and weaker incremental payback.
  • A smaller system may have better marginal economics but provide less future expansion capacity.
  • Rules or rates may change during the system's life.

Information you may need

  • Hourly or monthly consumption
  • Production estimates for both system sizes
  • Export tariff and limits
  • Battery assumptions

Your next step

What to do next

Compare the incremental cost and value of the larger system under current, lower, and capped export-rate scenarios.

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