How to read a solar quote
Translate the familiar jargon into the questions that actually matter.
A solar quote can run to several pages and use a lot of terminology you have never needed before. This guide explains the key sections — so you know which numbers are important and which questions to ask.
System size (kWp)
This is the total peak output of the solar array. A higher number is not automatically better — it should match the size of your roof and your electricity use. An installer who proposes a very large system without asking about your usage is worth questioning.
Panel make, model and wattage
Individual panels are rated in watts (W). Divide the total kWp by the number of panels and you can check the per-panel wattage makes sense. A 400W panel is standard; anything well below that in a modern quote is worth querying. Look up the manufacturer's warranty: 25 years on performance, 10–12 years on the product itself is typical for a reputable brand.
Inverter type and brand
The quote should name the inverter. String inverters are less expensive; microinverters or optimisers cost more but help when shade is present. Ask whether the inverter is battery-ready — if you might add storage later, this matters.
Annual generation estimate
This is the installer's prediction of how many kWh the system will produce in a typical year. Divide it by the system kWp to get specific yield (kWh/kWp). For a south-facing UK roof this should be roughly 850–1,000. Numbers well above 1,000 are optimistic; numbers below 800 for a south-facing roof suggest conservative assumptions or potential shading.
What is included in the price
A complete installed price should include: panels, inverter, mounting hardware, DC and AC wiring, installation labour, connection to your distribution board, and registration with your Distribution Network Operator (DNO). Scaffolding, electrical remediation work, and monitoring hardware are sometimes listed separately — ask.
Key takeaways
- Check that system size matches your roof and your usage — bigger is not always better.
- Divide annual generation by kWp to get specific yield: 850–1,000 is typical for a south-facing UK roof.
- Confirm what is and is not included in the total price — scaffolding is a common extra.
- Ask whether the inverter is battery-ready if you might want storage later.
This guide is for general information only. It is not a substitute for a survey of your home or professional advice. Solar Help Centre does not install solar equipment or produce the final design for your home.
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