Solar Questions, Clearly Answered

Solar panels turn daylight into electricity. Photovoltaic (PV) cells inside each panel produce direct current (DC) electricity when light hits them, and an inverter converts that into the alternating current (AC) electricity your home, business and appliances use.

Any electricity you don't use at the moment it's generated either goes into a battery (if you have one) or is exported to the grid. The amount generated depends on the system size, the roof and the weather, not on direct sunshine alone.

For many UK homes, yes, but it depends on your property and how you use energy.

The UK has enough daylight for solar to work well, particularly because panels perform better in cool conditions. Whether the numbers work for you depends on your roof's orientation and shading, your electricity usage, and what you currently pay per kWh. Domestic solar currently attracts 0% VAT until March 2027.

See our guide Are solar panels worth it? for a full breakdown, or ask us for an assessment based on your actual property.

It depends on the system size (measured in kWp), the roof's orientation and tilt, any shading, and where you are in the country.

As a general UK reference, a 4 kWp domestic system might generate in the region of 3,000 to 3,500 kWh a year. A proper design estimate should be worked out for your specific roof, not taken from a national average.

Yes. Panels generate from daylight, not heat, so they produce electricity throughout the UK winter, just considerably less, because the days are shorter and the sun is lower.

Generation peaks in late spring and summer and drops in December and January. Snow rarely settles long on tilted panels, and cool temperatures actually help panel efficiency.

Yes. Solar panels generate from diffuse light as well as direct sunlight, so they keep producing on overcast days, at a reduced output compared with bright, sunny conditions.

Because the UK has many cloudy days, panels are designed and tested with exactly these conditions in mind.

It depends on how much electricity you use, when you use it, your budget and how much usable roof space you have, not on a fixed rule.

Sizing normally starts from your annual electricity consumption in kWh and your daytime usage pattern. A well-designed system is sized around your property rather than selling a standard package.

Quality panels are built to keep generating for decades. Most come with performance warranties of 25 years or more, and output declines only slowly over time.

Other parts of the system have shorter lives. The inverter in particular may need replacing during the system's lifetime.

Each panel takes up roughly 2 square metres of roof, so the space needed depends on how many panels your design requires.

As a rough guide, a typical domestic array of around 10 panels needs in the order of 20 square metres of unshaded roof. Usable space depends on roof shape, obstructions such as chimneys or roof lights, and which faces get good daylight.

A standard grid-connected solar system shuts down during a power cut. This is a safety requirement, so the system cannot push electricity onto the network while engineers are working on it.

If backup power matters to you, a battery system with a backup function can keep selected circuits running during an outage, but it depends on the equipment and how the system is configured, so it needs to be designed in from the start.

Most roofs can take solar, but not every roof should. The key factors are the roof's structural condition, the covering type (tiles, slate, metal sheet and others are all workable), the available area, its orientation and any shading.

Flat roofs use ballasted, non-penetrating frames rather than roof fixings. A proper survey will tell you honestly whether your roof is suitable.

It depends on how and when you use electricity. A battery makes most sense if you are out during the day, use a lot of electricity in the evening, have an EV, or want to store cheap-rate grid electricity on a time-of-use tariff.

If you use most of your electricity while the sun is shining, you may already self-consume most of your generation, in which case a battery adds less. We've written a fuller guide, is battery storage worth it on an existing solar system?, and you can read about our battery storage service.

It should be sized against your actual consumption, how many kWh you use in a day and specifically in the evening and overnight, not simply matched to the size of your solar array.

Domestic batteries commonly fall between roughly 5 kWh and 15 kWh of usable capacity, but the right figure for you comes from your usage data. Oversizing a battery is the most common sizing mistake.

Yes, in most cases. There are two usual routes: replace the existing inverter with a hybrid inverter that manages the battery directly, or add an AC-coupled battery alongside the existing inverter.

Which one suits you depends on the age and type of your current system. See our guide to retrofitting battery storage.

Modern lithium-based batteries are typically warrantied for around 10 years, or a stated number of charge cycles, and should last longer than the warranty period with gradual capacity loss along the way.

Actual life depends on the chemistry, how often it cycles and the environment it's installed in.

Yes, most modern battery systems can charge from the grid as well as from solar. This lets you store cheap overnight electricity on a time-of-use tariff and use it during expensive periods.

Whether this is worthwhile depends on the tariff you're on and your usage pattern, and it needs to be configured in the system settings.

Yes. A battery system can be installed on its own and charged from the grid, typically to take advantage of cheap-rate tariffs. This is sometimes called battery-only or AC-coupled storage.

Whether it makes financial sense depends heavily on the difference between your cheap-rate and peak-rate electricity prices.

It depends on the system. A standard battery installation without a backup function shuts down along with everything else.

Systems specified with backup capability can continue to power selected circuits, sometimes the whole property, during an outage. This must be designed and wired in deliberately, so it's worth raising before installation if backup power matters to you.

Common locations include garages, utility rooms and other outbuildings, and many models can be installed outdoors. Each manufacturer specifies clearances, temperature limits and location rules that the installation must follow.

The best spot balances ventilation, accessibility, cable runs and the equipment's environmental rating. This is assessed at design stage.

Battery capacity is measured in kilowatt-hours (kWh). A 10 kWh battery can store up to 10 kWh of usable electricity, though some of a battery's stated capacity may be reserved by the manufacturer to protect the cells.

For scale, a typical UK household uses somewhere around 7 to 10 kWh of electricity per day, so a mid-sized battery can cover a large part of an evening and overnight.

Yes, in two ways: storing your own solar generation to use in the evening instead of buying it back from the grid, and storing cheap-rate grid electricity if you're on a time-of-use tariff.

How much you actually save depends on your usage pattern, your tariff and how the system is configured. An honest estimate should be based on your own consumption data, not a generic figure.

Yes. Solar generation can feed directly into charging your electric vehicle, either by charging while you generate surplus, or through a smart EV charger that matches the charging rate to your available solar output.

How much of your driving can be covered by solar depends on your generation, your mileage and when the car is home. Your charging habits matter as much as the panels.

For most UK homes, a 7 kW single-phase charger is the practical choice. It's the fastest charging rate most domestic electricity supplies support and comfortably recharges a car overnight.

Faster chargers (11 kW or 22 kW) need a three-phase supply, which most homes don't have. More on this below, and on our EV charging page.

The main difference is charging speed and the electricity supply they need. A 7 kW charger runs on the single-phase supply found in most UK homes; a 22 kW charger needs a three-phase supply and can charge roughly three times faster.

A 22 kW charger on a single-phase home supply won't achieve its rated speed, so the extra cost is usually wasted unless the property actually has three-phase power.

Yes. Many smart EV chargers have a solar-matching mode that monitors your surplus generation and adjusts the charging rate to use it, so the car effectively charges on your own electricity.

You can usually choose between charging purely on surplus solar, on a mix of solar and grid, or at full speed regardless, depending on how quickly you need the car ready.

In some setups, yes, the battery can discharge to support EV charging, and some systems allow the battery to prioritise the car. Whether it works in your case depends on the inverter, the battery and the charger, and how they communicate.

It's worth noting the trade-off: energy sent to the car is energy not covering your home's evening use, so most systems prioritise the home unless configured otherwise.

A charger needs somewhere to park the car beside it and an electricity supply the installer can connect to. For homes with off-street parking, installation is usually straightforward; flats, rented properties and shared parking need a bit more assessment and sometimes permission from the landlord or site owner.

The condition and capacity of the existing supply is checked as part of the survey.

It depends on the car's battery size and the charger's power. As simple arithmetic: a car with a 60 kWh battery on a 7 kW home charger takes roughly 8 to 9 hours for a full charge, which is why overnight home charging suits most drivers.

A 3-pin socket emergency lead charges far more slowly, and public rapid chargers are much faster but more expensive per kWh.

Yes. An EV charger is a high-power piece of equipment and should be on its own dedicated circuit, installed in line with UK wiring regulations, with the necessary protection and any load management your supply requires.

This is not a plug-in job. A qualified installer surveys the supply, fits the dedicated circuit and certifies the installation.