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What changes

Curtailable inverter

• On a plan whose feed-in price goes below zero (Amber), the planner assumes by default that the panels switch off at those times. "What to ask installers for" now asks for a "curtailable" inverter of that size.
• The recommendation and the option's detail say why, with the hours of negative feed-in, and point to Amber's list of supported inverters.
• For homes that already have panels, they also say the existing inverter needs to be curtailable.
• With "Panels switch off…" unticked, they instead say what a curtailable inverter would avoid.
• On Amber, a battery should be one SmartShift can run, or one you automate yourself.
• The switch-off setting's label and help now say it needs a "curtailable" inverter.

New "Check the numbers" card, following the option on show:

• Averages: power bought and sent out, average price per kWh bought, average earned per kWh sent out (net of any export charge), daily charges, demand charges and the bill. These are shown for the yardstick, for the same plan with nothing new, and for the option.
• Prices through the day: the plan's plain average buy and feed-in price for night, morning, middle of the day and afternoon/evening, plus how often feed-in is below zero.
• Rules of thumb:
  • kWh a day per kW of panels, against installers' usual 3.5 to 4.4.
  • What each kWh of new solar or battery output is worth against what it costs per kWh over its life.
  • Hours of negative feed-in.
  • The planner's bill for the readings' plan, to compare with real bills.
• What it assumes: panels, inverter, battery, export limit, negative feed-in, up-front cost breakdown, price rises and the money settings.

Help, README and tests are updated. The version is now 1.59.

Testing

• All unit tests pass.
• All 54 Playwright tests pass locally, including a new test of Amber's curtailable-inverter note with the setting ticked and unticked.
• New checks on the numbers card: the bill it shows matches the month table's year.

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