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Worked decision examples

Home-energy decisions with the assumptions exposed

These pages give a useful result before you touch a calculator. They use clearly labelled illustrative assumptions, sensitivity tables and direct links back to editable tools.

Home battery payback3–20 kWh worked payback sensitivityBattery size optimiser5 kWh vs 10 kWh using daily shiftable-energy scenariosSolar + battery vs solar only5–30 kWh battery examplesSolar self-consumption2,000–8,000 kWh annual generation examplesSolar system size2–12 kWp illustrative output referencesHeat pump vs gas6,000–20,000 kWh useful heat demandEV tariffs1,000–5,000 kWh annual EV charging, whole-home viewAppliance running costs15 distinct household appliancesAir fryer vs oven1–10 uses/weekCheap-rate appliance shiftingEight household-use profilesHeat-pump dryer payback1–10 cycles/week
Important: tariff rates, installation prices, grants, product performance and household use change. These are planning examples, not current-price claims, guaranteed savings, financial advice or engineering approval.

Why these examples use ranges instead of one answer

Home-energy decisions are sensitive to household behaviour. A battery that cycles daily can have a very different payback from the same battery used occasionally; an EV tariff can be attractive for heavy overnight charging but poor for a household with high daytime demand. The examples therefore show ranges and expose the inputs rather than presenting a single national answer.

Each topic is consolidated into one comparison page so you can scan the whole range before opening the relevant calculator. That avoids treating small changes in capacity, annual use or weekly frequency as completely separate decisions.

A good way to use the site

Start with the worked range closest to your situation. Then open the calculator and replace the illustrative assumptions with your tariff, quote, appliance data or household energy use. Finally, change the most uncertain input up and down. If the conclusion changes easily, the decision is sensitive and deserves better data before money is committed.

These tools are planning aids. They do not predict future energy prices, guarantee product performance or replace installer design work. Their purpose is to make the arithmetic transparent enough that you can challenge a quote or compare alternatives on a consistent basis.