If you’re considering solar panels for your home, understanding how they actually work is a good place to start. The technology is simpler than most people expect, and knowing the basics will help you make better decisions about system size, placement and whether to add battery storage.
The Basics: Sunlight to Electricity
Solar panels — properly called photovoltaic or PV panels — convert sunlight directly into electricity. Each panel contains cells made from semiconductor material (usually silicon) that generate an electrical current when exposed to light.
The electricity produced by the panels is direct current (DC), which isn’t the type your home uses. An inverter converts this into alternating current (AC) — the standard electricity that powers your lights, appliances, and everything else in your home.
From there, the electricity follows a simple priority order. First, it powers whatever your home needs at that moment. If your panels are generating more than you’re using, the surplus either charges a battery (if you have one) or gets exported to the grid. If your panels aren’t generating enough to cover your usage — at night, for instance — your home draws from the battery or the grid as normal.
Do Solar Panels Work in Cloudy Weather?
Yes. This is one of the most common questions we hear, and it’s understandable given the British climate. Solar panels respond to daylight, not direct sunshine. They’ll generate less on an overcast day than on a bright one, but they still produce electricity throughout the year.
Sussex is actually one of the better locations in the UK for solar, with around 1,900 hours of sunshine annually. Even during the shorter winter months, a well-designed system continues generating meaningful output.
Does My Roof Need to Face South?
A south-facing roof will generate the most electricity, but it’s no longer the only viable option. Modern panels are efficient enough that east and west-facing roofs work well too — you might see 15–20% less generation compared to due south, but the system will still deliver strong returns.
The only orientation we’d generally advise against is north-facing, where direct sunlight is very limited.
Beyond compass direction, shading is the more important factor to consider. Trees, chimneys, neighbouring buildings — anything casting shadow on your panels during the middle of the day (roughly 10am to 4pm) will reduce output. If partial shading is unavoidable, we can fit panels with optimisers. These allow each panel to operate independently, so a shadow falling on one panel doesn’t drag down the performance of the others.
What Size System Do I Need?
System size depends on your electricity usage, available roof space and budget. As a general guide:
A smaller home with lower energy consumption might suit a 3–4kW system (around 7–9 panels). A larger household with higher usage — especially one with an EV or heat pump — could benefit from a 5–6kW system or larger (12+ panels). Each panel takes up roughly 2 square metres, so your usable roof area will determine what’s physically possible.
We assess all of this during a free site survey, designing every system around your specific property and energy patterns rather than offering a one-size-fits-all package.
What About Battery Storage?
Without a battery, any solar electricity you generate but don’t immediately use gets exported to the grid. You receive a payment for this through the Smart Export Guarantee (SEG), but the export rate is usually much lower than what you pay for grid electricity — so using your own solar power is always more valuable than selling it.
A battery stores your surplus generation so you can use it later — typically in the evening when your panels have stopped producing but your household is still using electricity. This can dramatically increase the proportion of solar energy you consume yourself, which is where the biggest savings come from.
You don’t need to install a battery from day one. We design all our systems to be battery-ready, so you can add storage later when the timing and budget are right.
Do I Need Planning Permission?
In most cases, no. Residential solar panel installations in England and Wales are typically classed as permitted development, meaning no planning application is required.
The main exceptions are listed buildings and properties in conservation areas, where you may need approval from your local council. If this applies to your home, we’ll advise you during the survey.
What Maintenance Do Solar Panels Need?
Very little. Solar panels have no moving parts, so there’s almost nothing that can wear out or break. British rainfall does a reasonable job of keeping panels clean, and beyond keeping nearby trees trimmed to avoid shading, there’s not much you need to do.
The one component with a shorter lifespan is the inverter, which typically lasts 10–15 years before needing replacement. Budget around £800–£1,000 for this when the time comes. The panels themselves are warrantied for 25–30 years and often continue performing well beyond that.
We’d also recommend considering bird deterrent mesh during installation. It prevents pigeons and other birds from nesting beneath your panels — a common issue that’s much easier and cheaper to deal with at the point of installation than after the fact.
Making the Most of Your System
Once your panels are up and running, the single most effective thing you can do is shift your electricity usage into daylight hours. Run your washing machine, dishwasher and tumble dryer during the day. If you have an EV, charge it while the sun is up. Programme timers on anything you can.
Every unit of solar electricity you use yourself saves you the full retail rate. Every unit you export earns you a fraction of that. The more you can align your usage with your generation, the faster your system pays for itself.
Can I Still Switch Energy Supplier?
Absolutely. Having solar panels doesn’t lock you into any particular energy provider. Your electricity supplier and your SEG export tariff provider don’t even need to be the same company, so you’re free to shop around for the best deals on both.
Some suppliers do offer better export rates if you also take your main supply from them, so it’s worth comparing the combined package rather than looking at each in isolation.
Combining Solar with Other Technologies
Solar PV pairs naturally with other renewable technologies. Adding battery storage is the most common combination, but solar also works brilliantly alongside heat pumps (using free solar electricity to run your heating) and EV chargers (fuelling your car from your roof).
When these technologies are designed to work together from the outset, the whole system becomes significantly more efficient than the individual parts. It’s something we consider during every project — even if you’re only installing solar now, we’ll make sure the system is ready for whatever you might want to add later.
How Do Solar Panels Generate Electricity? Step by Step
If you want the short version, here is the whole process in five steps:
- Sunlight hits the panel. Photons from daylight strike the silicon cells on your roof — direct sun is best, but daylight alone is enough.
- The cells release electrons. The silicon absorbs that light energy and knocks electrons loose, creating a flow of direct current (DC) electricity.
- The inverter converts it. Your home runs on alternating current (AC), so an inverter converts the DC electricity into usable AC power.
- Your home uses it first. The electricity flows to whatever is switched on — fridge, kettle, heat pump, EV charger — before anything else.
- The surplus is stored or exported. Anything you do not use charges a battery if you have one, or is exported to the grid and paid for under the Smart Export Guarantee.
That cycle repeats every daylight hour, all year round. Adding battery storage to the chain is what lets you use your own solar power in the evening rather than buying it back from the grid.
How Many Solar Panels Do I Need?
This is the question we are asked most often. The honest answer is that it depends on how much electricity you use, how much roof space you have, and which direction it faces — but the table below is a realistic starting point for a typical UK home.
| Home size | Typical annual usage | System size | Panels needed | Roof space |
|---|---|---|---|---|
| 1–2 bedroom flat or house | About 1,800 kWh | 2–3 kW | 5–8 panels | About 10–15 m² |
| 3 bedroom family home | About 2,900 kWh | 4 kW | 10–11 panels | About 20 m² |
| 4 bedroom home | About 4,100 kWh | 5–6 kW | 13–16 panels | About 26–32 m² |
| 5+ bedroom or high usage | 5,000 kWh and above | 6 kW and above | 16+ panels | About 32 m² and above |
As a rule of thumb, one modern panel produces roughly 400–450 watts, and a 4 kW system generates somewhere around 3,400–4,000 kWh a year in Sussex — enough to cover most of a typical family home’s electricity. If you run an electric car or a heat pump, size up: those loads can easily double your consumption.
For what a system like that actually costs, see our solar panel cost guide.
Do Solar Panels Work in Winter?
Yes — and this is one of the biggest misconceptions about solar in the UK. Panels are driven by daylight, not heat or direct sunshine, so they generate every day of the year. In fact solar cells are slightly more efficient in cold conditions than in high summer heat.
What does change in winter is the amount of daylight available. Expect roughly:
- Summer (May–August) — peak output, often 50–60% of your annual generation in these four months alone.
- Spring and autumn — strong, steady generation on long bright days.
- Winter (November–January) — typically 15–25% of a summer day’s output, with short daylight hours.
Snow is rarely an issue in Sussex, and when it does settle, panels are mounted at an angle and warm slightly as they generate, so it usually slides off within a day. Frost and cold cause no harm at all.
The practical takeaway: a well-designed system is sized around your annual generation, with strong summer output balancing the quieter winter months.
Common Questions About How Solar Works
What is the 33% rule for solar panels?
It is a rough guide suggesting a typical home without a battery only uses around a third of the electricity its panels generate — the rest is exported, because most generation happens midday while the house is empty. It is the single best argument for adding a battery, which can lift self-consumption to 70–80%.
Is 3kW enough to power a house?
A 3 kW system generates roughly 2,500–2,800 kWh a year, which covers most of a smaller home or a low-usage couple. For a three or four bedroom family home — especially with an EV or heat pump — 4 kW and above is usually the better fit.
What happens after 25 years of solar panels?
They keep working. The 25-year figure is a performance warranty, not a lifespan: most manufacturers guarantee around 85–90% of original output at year 25, and panels commonly run well beyond 30 years at gradually reducing efficiency. The inverter is the part most likely to need replacing first, typically at 10–15 years. Regular solar panel maintenance keeps the whole system performing.
Do solar panels work at night?
No — there is no daylight to convert, so generation stops at dusk. This is exactly what battery storage solves: it stores your surplus daytime generation and releases it through the evening and overnight.
Do solar panels work on a cloudy day?
Yes, just at reduced output. On an overcast UK day panels typically produce somewhere between 10% and 40% of their bright-sunshine output — still a meaningful contribution, and the reason solar works perfectly well in the British climate.
Where to Go Next
If you are weighing solar up, these will help: our solar panel cost guide for real pricing, the Smart Export Guarantee guide for how export payments work, in-roof vs on-roof panels if you care about how the panels look, and our full solar panel FAQs.
We install across East Sussex and West Sussex, covering solar panel installation, battery storage and EV chargers. If you would like a straight answer on what your own roof would do, book a free survey — no obligation.
Next Steps
If you’re thinking about solar for your home, the best starting point is a proper site survey. We’ll look at your roof, assess shading, understand your energy usage, and give you an honest picture of what a system would cost, what it would generate, and how long it would take to pay for itself.
There’s no obligation and no hard sell — just straightforward advice based on your specific property.
Greener Solar Solutions is the dedicated solar energy brand of A Greener Alternative. MCS certified, NICEIC approved, and serving homeowners across Sussex, Surrey, Hampshire and Kent.
