Tools

Nine
calculators.
Your numbers.

Every calculator is free. No sign-up, no paywall.

FreeFull result, no sign-up
01 · Available nowFree

Plug-in Solar
Savings Calculator

Is a balcony kit worth it for your home? Annual saving and payback from three inputs.

Open calculator →
Typical 800W, south
£130/yr
Payback
4.2yrs
02Next

Panel Orientation Day Planner

How south, east and west faces share the day's generation.

  • FreeDaily curve for your roof faces
Notify me when it's live
03Available now

Solar Clipping Visualiser

See when your inverter caps output on sunny days.

  • FreeClipped kWh on a clear day
Open visualiser →
04Planned

VPP Export Event Simulator

What a virtual power plant event would earn your battery.

  • FreeOne event, one battery
Notify me when it's live
05Planned

Heat Pump vs Gas Cost Calculator

Running cost comparison using SCOP, the seasonal efficiency figure.

  • FreeAnnual cost, heat pump vs boiler
Notify me when it's live
06Planned

Smart EV Charging Window Finder

The cheapest hours to charge, from tariff and solar.

  • FreeBest window for tonight
Notify me when it's live
07Planned

Battery Storage Size Calculator

How many kWh you actually need, not what you're sold.

  • FreeRecommended size range
Notify me when it's live
08Available now

Inverter Load Simulator

Switch appliances on and see when the grid takes over.

  • FreeLive load against your inverter and battery
Open simulator →
09Available now

Solar Forecast

What your panels should make over the next seven days.

  • Free7-day forecast for your roof
Open forecast →
On your iPhone

The calculators are coming to iOS first. Free, like everything here.

Tell me when it's out