Short answer: A good quote shows the system size in kWp, the expected yearly generation for your roof, the panel, inverter and battery models, and says scaffold, 0% VAT and grid notification are included. In Derby, Checkatrade's published range is £7,780 to £12,526. Compare quotes for the same system, line by line.
The checklist
Work down this list with the quote in front of you. Anything missing is a question to ask the installer.
- System size in kWp: The total peak output of the panels. Everything else is compared per kWp.
- Panel make, model and number: So you can look up the specification and warranty.
- Inverter make, model and type: A standard inverter, or a hybrid that can take a battery now or later.
- Battery make, model and usable capacity: the usable kWh, which can be lower than the headline size.
- Expected yearly generation in kWh: For your roof’s direction and pitch, with shading taken into account.
- Scaffolding: Included, and for how long.
- VAT: A home install should show 0% until 31 March 2027 (HMRC VAT Notice 708/6).
- Grid notification: Who notifies National Grid Electricity Distribution, and whether you get a copy.
- Bird mesh: Included or extra, if pigeons are common where you live.
- Warranties: Panels, inverter, battery and the workmanship, and who backs each one.
- Payment terms: Deposit, stage payments and when the balance is due.
Checking the generation figure
The expected generation is the most useful number on a quote, because it drives every saving figure. PVGIS, the European Commission’s solar model, gives central Derby about 979 kWh per kWp a year on a south-facing roof and 773 kWh on an east or west-facing roof (PVGIS).
So a 4 kWp system facing south should be quoted at around 3,900 kWh a year, less if there is shade. If a quote shows much more, ask how it was worked out. If it shows the same figure whatever way the roof faces, it probably wasn’t worked out for your roof at all.
Checking the price
Published figures give a sense of what is normal in Derby. Checkatrade lists solar panel installation at £7,780 to £12,526, averaging £9,831, and battery storage at £4,317 to £7,434, averaging £5,640 (Checkatrade). One Derby installer’s own guide says most homes fall between £5,500 and £7,500 for a basic system (Coactivation Solar).
A quote well above the range should come with a reason, such as a large battery, difficult access or premium panels. A quote well below it deserves a close look at what is left out.
Want a quote to compare against?
We quote on the same checklist, with the generation figure shown. Call or send your postcode.
Checking the savings claims
Savings depend on how much of the power you use at home. With the East Midlands price cap at 25.36p per kWh for 1 October to 31 December 2026 (Ofgem), each unit you use instead of buying is worth that much. Exported units are worth far less. A quote that assumes you use nearly all of the power, with no battery and nobody home in the day, is being optimistic. How much do solar panels cost in Derby? works through a realistic example.
Pressure selling
Be wary of quotes that are only valid today, discounts that depend on signing on the spot, or a “free” system that turns out to be a finance agreement. A fair installer will leave a written quote with you and give you time to compare.
Bottom line
A good quote states the system size, the expected yearly generation for your roof, the panel and inverter models, what the battery can actually store, and that scaffold, VAT at 0% and grid notification are included. Compare like with like, and question any quote that won't show the generation figure. Call 01332 919162, 9am to 7pm, 7 days.