The Short Answer
In our view, the panel matters less than the installer, the inverter and getting the size right. If you want a name, we'd fit Longi's Hi-MO 6: LONGi publishes up to 22.5% module efficiency for the Hi-MO 6 Explorer range, with a 15-year product warranty and a 25-year power warranty.
We no longer name a premium pick. The brand that held that slot, Maxeon (SunPower), has been under judicial management since 29 May 2026, and a long warranty is only worth what the company behind it is worth.
What the Datasheet Figures Mean
| Figure | What it means | What to look for |
|---|---|---|
| Module efficiency | How much of the sunlight hitting the panel becomes electricity | Matters most when roof space is short |
| Power (W) | Output in standard test conditions | Divide the system size by it to get the panel count |
| Product warranty | Defects in the panel itself | Who you'd claim from, and whether they're trading |
| Power warranty | A minimum share of rated output after a set number of years | The percentage and the years together |
| Temperature coefficient | Output lost per degree as the panel heats | Closer to zero is better |
The Energy Saving Trust says panels should last 25 years or more. Ask for the datasheet of the exact model on your quote and compare these lines.
Our Pick: Longi Hi-MO 6
LONGi's Hi-MO 6 Explorer page lists up to 22.5% module efficiency (on its largest panel), a 15-year product warranty and a 25-year power warranty. Our view: that's as much efficiency as an ordinary UK roof needs. Check the efficiency of the exact panel size you're quoted, because smaller panels in a range usually list a little less.
Why There's No Premium Pick
Maxeon's own homepage says its affairs are being managed by judicial managers appointed by the High Court of Singapore on 29 May 2026. If you already have Maxeon panels, they'll keep working; the lesson for a new buyer is to weigh a warranty by the company behind it, and to ask your installer in writing who handles a claim if the maker can't.
If You Want Panels Set Into the Roof
For a flush look, Marley's SolarTile is a full-size in-roof panel: Marley publishes 23.6% efficiency for the 445W all-glass version, a 15-year systems warranty for compatibility and weathertightness, and a power warranty of 95% at 10 years and 87% at 30. Our tiles vs panels guide covers the cost.
How Many Panels?
Solar panel calculator
How many solar panels do you need?
Uses the European Commission's PVGIS solar model for your region and roof direction, not a single UK average.
On your bill or annual statement. Ofgem's typical home uses 2,500kWh.
Planning to add
Car: 7,100 miles a year at 3.3 miles per kWh (EV Database). Heat pump: 9,500kWh of heat at a SCOP of 3.5.
Which way does the roof face?
East and west roofs often split the panels across both sides, which suits a home that uses power morning and evening.
Panel size
Each panel is about 1.72m by 1.13m.
You need
6 panels
A 2.58kWp system, about 12 square metres of roof, making around 2,500kWh a year, enough to match your yearly use of 2,500kWh.
969
kWh per kWp a year here
£5,000
typical cost, 0% VAT
£421/yr
bill saving plus export
12 years
to pay for itself
Making as much as you use isn't the same as not buying any. Without a battery, on the government's SAP 10.2 self-use formula this home would use about 34% of its solar as it's made; the rest goes to the grid at the export rate and you still buy power after dark.
Yield: PVGIS v5.2, 35 degree pitch, 14% system losses, unshaded. Value: 34% used at home (the government's SAP 10.2 self-use formula for this system and your yearly use) at 26.32p, the rest exported at 12p (Outgoing Octopus, for Octopus supply customers on eligible tariffs). Cost at DESNZ's 2025/26 mean for home installs: £1,955 per kWp under 4kW, £1,645 from 4kW. Shading, pitch and your own tariff will move these numbers.
What to Ask Your Installer
- The make and model of panel and inverter, in writing.
- The datasheet, with the efficiency of that exact panel size.
- Who handles a warranty claim: the maker, a UK distributor or the installer.
- That the products are MCS-certified, which an export tariff may require.
What You Don't Need
- A premium panel to squeeze in a few more watts, in our view, unless the roof is short of space.
- A long warranty from a company in trouble.
Choosing the inverter matters as much: see our inverter types guide. Then what solar costs.
Find out which panels your roof should have
The best panel for your home depends on roof space, budget, and shading. Get personalised quotes from MCS-certified installers and compare the kit they'd actually fit. Free, no obligation.
Frequently Asked Questions
Solar Panel Accessories Worth Having
Once your panels are installed, these help you keep an eye on them and look after them.
Solar Panel Cleaning Kit with Extension Pole
£42.57A soft brush on a telescopic pole, for rinsing panels you can reach safely from the ground. Most rooftop panels are cleaned well enough by rain.
6m telescopic poleFind on Amazon
Solar Panel Bird Proofing Mesh Kit (30m)
Check priceMesh that clips around the edge of the panels to stop birds nesting underneath. Best fitted by an installer, since it means working at height.
30m roll + 60 clipsFind on Amazon
OWON WiFi Smart Energy Monitor
£50.39Shows how much electricity your home, or your heat pump on its own circuit, is using in real time.
WiFi + 3x CT clampsFind on AmazonAs an Amazon Associate we earn from qualifying purchases. Prices and stock are checked against Amazon every few hours and may have changed since.
