Start with the essentials
Ask the installer to show the assumptions behind the estimate: orientation, shade, losses, monthly output and local tariffs. Separate the value of electricity used at home from the value of exported electricity. Fixed charges may remain.
What you can do
- Use twelve months of bills instead of only the highest summer bill.
- Compare total installed costs, finance charges and likely maintenance.
- Ask for a conservative case as well as the installer’s central estimate.
Keep in mind
Future generation and tariffs are uncertain. Treat a savings forecast as an estimate with assumptions, not a guaranteed return.
Further reading & official resources
Check current terms and guidance with the responsible provider. References are for background reading and do not imply endorsement.
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