The starting point

Assess the whole electricity bill: when energy is imported, what exported energy earns, battery losses and the standing charge. A single attractive unit rate cannot describe the complete result.

Keep the baseline honest

Compare the home before and after installation using the same tariff, demand and time period. Then run a separate comparison if you are also considering a tariff change.

If your bill already includes EV charging, avoid adding the same charging demand again. If consumption is inferred from a bill, record how standing charges and multiple unit rates were handled.

Use the actual time windows

Record the start and end of each rate window and check how the supplier expresses time. Distinguish fixed daily windows from prices that change by settlement period.

For a battery, also consider whether overnight charging leaves enough room for the following day’s solar. A cheap charge is not automatically the best use of the available capacity.

Read the export terms

Check the supplier’s eligibility, metering and payment terms before relying on export income. Ask specifically how stored energy is treated.

  • Import rates and standing charge.
  • Export rate and applicable conditions.
  • Battery charging window and operating priority.