Path-Q Solar

What electricity-bill details are needed to account for time-based usage charges in a solar design?

Answer

Provide the complete tariff and enough consumption data to show when electricity is used. The designer needs more than total kWh: they may need time-period prices, peak definitions, fixed charges, export treatment, demand charges, taxes or other adjustments, and interval consumption if available.

Key points

  • Identify peak, shoulder, and off-peak periods, including seasonal or weekday differences.
  • Provide separate import and export rates or credits and any limits or settlement rules shown on the bill or tariff.
  • For demand-billed accounts, provide interval demand data and the demand-charge calculation.
  • Include the billing period, meter type, account classification, and any rate-plan alternatives being considered.

What it depends on

  • The applicable current tariff and account type
  • Availability and quality of interval meter data
  • Whether charges depend on time, maximum demand, or both
  • How solar exports and storage are credited

Risks and trade-offs

  • Using a flat average rate can materially misstate savings under time-based pricing.
  • A design that reduces kWh purchases may not reduce demand charges without reducing the relevant peak.
  • Missing fixed or minimum charges can make projected bill savings look too high.

Information you may need

  • Several complete recent bills
  • The current tariff or rate-plan document
  • Interval load data if available
  • Export, demand, fixed-charge, and seasonal-rate details

Your next step

What to do next

Give the designer complete bills and the current tariff, and ask them to show savings separately for energy, demand, export credits, and fixed charges.

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

SQ01392