6kW Solar Panel System UK: The EV and Heat Pump Sweet Spot

A 6 kWp solar system sits at a useful threshold. It generates enough electricity to cover a large family home's baseline consumption and still produce a meaningful surplus for energy-hungry loads like electric vehicle charging or a heat pump. If you have been deciding between 5 kWp and something larger, 6 kWp is often where the numbers tip in favour of going bigger.

This article covers what a 6 kWp system involves, what it costs, how much it generates, and when it makes more sense than a 5 kWp system.

What does a 6kW system look like?

A 6 kWp solar system typically consists of:

• 13–14 panels at around 450W each (13 × 450W = 5,850W; 14 × 450W = 6,300W — both are sold as 6 kWp systems)
• Roof space: approximately 26–28 m² of usable, unshaded south-facing roof
• Inverter: a 6 kW string inverter, or a hybrid inverter if battery storage is planned

Thirteen panels can be arranged as a 7+6 split, or as a single continuous run of 13 on a wide rear slope. Fourteen panels might sit as 7+7 across two symmetrical pitches. If your roof has some east-west orientation, installers sometimes split the array to maintain output across a longer daily window, trading peak midday generation for a flatter morning-to-evening curve.

Which properties suit 6 kWp?

• 4-bed semi-detached or end-of-terrace: a rear slope that fits 11 panels at 5 kWp will often stretch to 13 with a modest extension of the array
• 4-bed detached: 6 kWp is a common starting point; roof area is rarely a constraint
• Larger bungalow: good roof footprint often makes 6 kWp straightforward
• 3-bed property with an EV or heat pump: demand justifies a larger array even on a smaller house

How much does a 6kW system cost?

The 0% VAT on supply-and-install applies until 31 March 2027. After that, VAT reverts to 5%.

The step from 5 kWp to 6 kWp typically adds £1,000–1,500 to the installed cost — reflecting two or three extra panels and a slightly larger inverter. Scaffolding and labour are essentially unchanged. On a cost-per-kWp basis, 6 kWp compares favourably with 5 kWp, particularly if you are already paying for a full installation day.

How much electricity will a 6kW system generate?

Using the UK average yield of approximately 850 kWh per kWp per year:

• Annual output: approximately 5,100 kWh
• Summer peak (May): approximately 715 kWh
• Winter trough (December): approximately 175 kWh

By location:

These figures assume a south-facing roof pitched at 30–35 degrees with no significant shading. East or west-facing roofs typically produce 15–20% less annually, though east-west splits can reduce this penalty by spreading generation across more daylight hours.

How much will I save?

Using April 2026 rate benchmarks, with an import rate of 24p/kWh and a basic SEG export rate of 3.3–5.2p/kWh:

Self-consumption is the key variable. Every unit you use directly from your panels displaces a unit you would otherwise import at 24p. Every unit you export instead earns only 3.3–5.2p on a basic SEG tariff — a significant difference. The practical implication is that a battery, a solar-diverting EV charger, or a hot water diverter (such as a myenergi Eddi) can meaningfully increase the financial return from a 6 kWp system by capturing surplus that would otherwise be exported cheaply.

Is 6kW enough for my home?

"Covers X%" means annual generation divided by annual consumption — but the seasonal distribution matters as much as the annual total. A 6 kWp system generates very little in December and January. The surplus occurs in summer, and unless you have storage or can shift demand (such as daytime EV charging), some of that summer surplus will be exported at low rates while you continue to import electricity in winter.

When 6 kWp makes sense over 5 kWp

You have an EV. Electric vehicles add roughly 2,000–4,000 kWh per year in home charging. A solar-optimised EV charger routes surplus generation directly into the car battery rather than exporting it cheaply. A 6 kWp system produces approximately 850 kWh more per year than a 5 kWp system — a meaningful difference for EV diversion, particularly on spring and autumn afternoons when generation is strong but not at peak.

You have a heat pump. Heat pumps add 3,000–6,000 kWh per year depending on the property and climate. They run most heavily in winter when solar output is lowest, but they also run in spring and autumn when a 6 kWp system generates well. Covering more of that shoulder-season demand is one of the clearest practical arguments for stepping up from 5 kWp.

Your household consumption is well above average. A family of four or five with home working, a tumble dryer, and higher general usage may consume 4,000–5,000 kWh per year before adding any electrified transport or heating. At that consumption level, a 6 kWp system covers roughly the same proportion of demand that a 4 kWp system would for a typical household.

Your roof can accommodate 13–14 panels without compromise. If the incremental cost is modest and your roof has the space, the cost-per-kWp at 6 kWp is roughly the same as at 5 kWp. There is rarely a reason to stop at 5 kWp if 6 kWp is straightforward.

A note on grid connection

A 6 kWp system is typically still within the G98 self-notification pathway for most domestic properties, provided export limiting is in place. Under G98, your DNO (distribution network operator) simply needs to be notified — you do not need to wait for approval.

However, on a single-phase supply, the export limit under G98 is 3.68 kW per phase. A 6 kWp system can generate more than that at peak output. Installers handle this either by configuring export limiting on the inverter (which caps export at the permitted level and wastes nothing — the surplus is still available for self-consumption) or by applying under G99 where full export is desired.

Your installer will determine the correct pathway for your property. It is worth confirming with them how export limiting is configured and whether it affects what you can claim under the SEG.

Can I add a battery?

Yes. A 6 kWp system pairs well with a 5–13 kWh battery. The larger the system, the more surplus there is to store — particularly from April through September when daily generation often exceeds household consumption by a considerable margin.

Common pairings to consider:

• 5 kWh battery: captures most surplus on overcast spring and autumn days; may not fully charge on long clear summer days
• 10 kWh battery: the most popular pairing at 6 kWp; captures a larger share of summer surplus and provides meaningful evening coverage
• 13 kWh battery: worth considering if you have an EV or heat pump and want to maximise self-consumption; also useful for Octopus Flux or similar export-optimising tariffs

Battery costs as of April 2026 are approximately £3,000–4,500 for a 5 kWh unit and £4,500–6,500 for a 10 kWh unit, installed.

Can I add more panels later?

Most 6 kW inverters accept up to 7.5–9 kWp of solar input. Oversizing the DC array relative to the inverter's AC output is standard practice and is within most manufacturers' specifications. This means adding 2–4 more panels to a 6 kWp system is often possible without replacing the inverter — though you should confirm the maximum PV input capacity for your specific inverter before purchasing additional panels.

If you are planning to expand the system later, it is worth telling your installer at the point of original installation. They can leave space in the roof layout, size cable runs appropriately, and specify an inverter with headroom for expansion.

See the guide to adding panels to an existing system for more detail.

Next steps

• How to size your solar system — the full sizing methodology
• How much do solar panels cost in the UK? — UK-wide cost guide
• How many solar panels do I need? — practical sizing tool
• 5kW solar system UK — if 6kW feels like more than you need
• 8kW solar system UK — if you have an EV and a heat pump together
• Adding panels to an existing solar system — if you want to expand later

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