How solar works, in one minute
Solar is simpler than most sales pitches make it sound. Daylight becomes electricity, your home uses what it can right away, and the grid quietly covers the rest. Here is the straight version.
- The panels: photovoltaic cells turn daylight, not heat, into DC electricity. They still work under cloud, just less.
- The inverter: converts that DC into the AC your home and appliances actually run on.
- Real-time use: the electricity powers whatever is on at that moment first. That is the cheapest unit you will ever use.
- The surplus: anything you are not using is stored in a battery, if you have one, or sent to the grid.
- At night and in winter: the panels stop, so you buy from the grid as usual. Solar shrinks the bill, it does not delete it.
- The headline: you are not going off-grid. You become a much smaller customer of it.
What a solar panel actually does
A solar panel makes electricity from light, not from heat. Each panel is a grid of photovoltaic cells, usually silicon, and when daylight lands on them it knocks electrons loose and pushes them in one direction, which is an electric current. A typical domestic cell converts around a fifth of the daylight hitting it into electricity; the rest is reflected or lost as warmth.
That "light, not heat" point matters, because it clears up the two most common myths in one go. Panels do not need direct, blazing sunshine, they run on daylight, so a bright overcast day in the Midlands still produces a useful amount. And they are not solar water heaters: a scorching day does not help, and in fact very hot panels are marginally less efficient than cool ones in good light. What a panel produces on its own is DC electricity, which is not yet in a form your home can use.
How the electricity gets from your roof to your kettle
The DC electricity from the panels runs to an inverter, which converts it into the 230-volt alternating current (AC) that your sockets, lights and appliances use. From the inverter it feeds into your consumer unit (the fuse board) and powers the house in real time, alongside the grid, without you having to switch anything over.
The share of what you generate that you use yourself, rather than send to the grid, is your self-consumption, and it is the number that really decides how much a system is worth to you. Every unit you use as it is made is a unit you did not buy. So a home where someone is in during the day, or where the dishwasher, washing machine and hot water can run while the sun is up, gets far more out of the same panels than a house that is empty until the evening. Getting that timing right, rather than simply fitting more panels, is where the real saving lives.
What happens at night, in winter and in the rain
At night your panels produce nothing and your home simply draws from the grid, exactly as it did before. Solar does not change how the dark hours are powered; it changes the daytime.
The seasons matter just as much in the UK. The winter sun sits low and the days are short, so a system generates only a fraction of its summer output over those months, while long June days can produce more than the house can use. This is why solar is always judged on what it makes across a whole year, not on a single bright afternoon or a grey week in January. Rain and cloud reduce output but never stop it, and a downpour has the useful side effect of rinsing dust off the glass. The one thing panels cannot do is work without daylight.
What solar does, and what it does not
A lot of the confusion around solar is really a handful of expectations that do not match how it works. Here is the reality of each.
| What people expect | The reality |
|---|---|
| Panels need direct sunshine to work | They run on daylight, so they still generate under cloud and rain, just less. Heat is not the point. |
| Solar makes you self-sufficient | It cuts what you buy, but most homes still draw from the grid at night and through winter. |
| My electricity bill will disappear | It shrinks. You still pay a standing charge and for power used when the panels are not producing. |
| More panels are always better | The right size is the one matched to what your home actually uses; oversizing just sends cheap power you paid to install straight to the grid. |
Wondering if your roof is right for it?
Whether solar stacks up comes down to your roof, your usage and when you use power. We look at all three and tell you straight, including if the answer is not yet. The assessment is free.
Book your free assessmentWhere a battery fits in
A battery stores the daytime surplus your panels make so you can use your own power in the evening, instead of buying it back from the grid at a higher rate. It is the answer to the "solar does nothing at night" problem, but it is not automatic that everyone needs one.
A battery earns its keep in a home whose electricity use is weighted towards the evening, after generation has stopped. A household that already uses most of its power during the day may do perfectly well without one. It is a question of when you use electricity, not whether a battery sounds like a good idea, and it is worth sizing honestly rather than to a headline number. We work through that with every quote alongside our battery storage installs.
The honest downsides
Solar's real drawbacks are the upfront cost, the fact that not every roof suits it, and a payback measured in years rather than months. Those are worth saying plainly, because a straight installer should raise them before you commit, not after.
- Upfront cost. As a UK market figure, a typical 3.5 kWp home system is around £6,100 (Energy Saving Trust), with the exact price depending on the roof and the kit. That is a real outlay before it starts paying you back, and it is a market figure, not an Apex quote.
- Not every roof suits it. Orientation, pitch, shading from trees or chimneys, and the condition of the roof itself all affect what a system will produce, and occasionally the straight answer is that solar is not the right move yet.
- Payback takes years. Solar is a long-term saving, not an instant one. It pays back gradually through lower bills over many years, so it suits people staying put rather than moving soon.
- Slow, gradual wear. Panels lose a little output over their decades of life rather than failing suddenly, much like a phone battery but far slower, which is why good ones are warranted to still hold a stated share of their output after around 25 years.
- You are still on the grid. Unless you go to considerable expense to store and manage it, solar reduces your reliance on the grid rather than removing it.
Common questions about how solar works
How does a solar panel work, step by step?
Daylight hits the panel and its photovoltaic cells turn that light straight into direct-current (DC) electricity. An inverter then converts the DC into the alternating current (AC) your home runs on. That electricity powers whatever is switched on at the time, and anything you are not using is stored in a battery if you have one, or sent to the grid. When the panels are not producing, at night or in winter, your home draws from the grid as normal.
Do solar panels work on cloudy days or in the rain?
Yes. Panels run on daylight rather than direct sunshine or heat, so they keep generating under cloud and in rain, just at a lower output than in bright conditions. A wet day washes dust off the glass, which does no harm. What they cannot do is generate in the dark, so output follows the daylight, high around midday and nothing overnight.
Do I still pay for electricity if I have solar panels in the UK?
Yes. Solar lowers your bill, it does not remove it. You still pay a daily standing charge to be connected, and you still buy electricity from the grid whenever the panels are not producing enough, which means most evenings, overnight, and through the darker winter months. Having solar makes you a smaller customer of the grid, not an independent one.
Do solar panels work at night?
No. Panels need daylight to generate, so they produce nothing after dark and your home draws from the grid instead. This is exactly the gap a home battery fills: it stores the surplus your panels make during the day so you can use your own power in the evening rather than buying it back.
Do solar panels work in winter?
Yes, but they generate a good deal less than in summer. In the UK the winter sun is lower and the days are much shorter, so a system produces a fraction of its summer output over those months. Across a whole year the summer surplus does most of the heavy lifting, which is why solar is judged on annual generation rather than any single day.
What are the main disadvantages of solar panels?
The real drawbacks are the upfront cost, that not every roof suits them, and that the payback takes years rather than months. Panels also lose a little output gradually over their decades of life, and they do not make you independent of the grid. None of these make solar a bad idea for the right home, but they are the things a straight installer should tell you before you commit.
About this resource
Written by the Apex Renewables team, who design and fit solar, battery and EV systems for homes across Leicester and the Midlands. The figures here are general UK market and industry figures, current as of July 2026, and are meant to explain how solar works, not to act as a quote.
We have tried to give you the honest version rather than the brochure one: what solar genuinely does, what it does not, and why the right-sized system beats the biggest one. If you want to know whether it stacks up for your home, see how we fit solar panels or talk it through with us.