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How solar panels connect to the grid and what that means for you
Your solar panels generate electricity from sunlight. But unless your home uses every unit the moment it's made, that electricity needs somewhere to go. That's where the grid comes in.
Most UK homes with solar panels are grid connected. This guide explains what that means, how the technology works, and what you can earn from the electricity you don't use.
What is the electricity grid?
The grid is the national network of cables, substations, and transformers that moves electricity around the UK. Power is generated in lots of different places: wind farms, solar farms, gas power stations. The grid delivers to homes and businesses up and down the country.
When your solar panels generate more electricity than your home uses, the surplus flows out to the grid. And when your panels aren't generating enough — at night or on cloudy days, you draw electricity back from the grid as normal.
How do solar panels actually generate electricity?
Each solar panel contains photovoltaic (PV) cells. When sunlight hits these cells, it creates a flow of electrons. That's direct current (DC) electricity.
Your home runs on alternating current (AC) electricity, and so does the grid. So the DC electricity from your panels needs to be converted before it can be used. That's the job of the inverter.
What does an inverter do?
An inverter converts DC electricity from your solar panels into AC electricity your home and the grid can use. It also keeps your solar system in sync with the grid's frequency and voltage.
There are three main types of inverter used in UK homes.
| Inverter type: | How it works: | Best for: |
|---|---|---|
| String inverter | All panels connect to one inverter. Simple and cost effective. | Homes with panels but no battery storage |
| Micro inverter | Each panel has its own small inverter. Better performance if panels are shaded. | Roofs with shading or complex layouts |
| Hybrid inverter | Manages both solar generation and battery storage in one unit. | Homes with or planning to add a battery |
OVO installs string and hybrid inverters depending on your system design. Your surveyor will recommend the right type for your roof and energy needs.
What happens to the electricity once it's generated?
Once your inverter converts the DC electricity to AC, here's what happens.
• Your home uses it first. Any appliances running at that moment draw from your solar generation directly.
• The surplus goes to your battery. If you have battery storage, extra electricity charges the battery for use later in the evening, or at night.
• Any remaining surplus exports to the grid. That's the electricity you can earn money from.
On a typical summer day, a 4kW solar system in the UK generates around 16 to 20 kWh of electricity. A typical UK home uses around 8 to 10 kWh per day. That leaves a good amount to store or export.
Can you earn money from exporting to the grid?
Yes. In the UK, the Smart Export Guarantee (SEG) pays you for every unit of electricity you export to the grid. You need to be registered with an SEG licensed supplier to receive payments.
OVO's current fixed SEG rate is 12p per unit exported. For a typical 4kW system exporting around 1,500 units a year, that's around £180 in annual SEG income on top of your bill savings.
| System size: | Estimated annual generation (UK average): | Estimated export (no battery): | Estimated SEG income at 12p |
|---|---|---|---|
| 3kW | 2,550 units | 900 to 1,100 units | £108 to £132 |
| 4kW | 3,400 units | 1,300 to 1,500 units | £156 to £180 |
| 5kW | 4,250 units | 1,600 to 1,900 units | £192 to £228 |
| 4kW + battery | 3,400 units | 400 to 600 units | £48 to £72 |
Estimates based on UK average solar generation of 850kWh per kWp per year. Export figures assume typical household daytime usage. OVO SEG rate correct as of May 2026.
What is a grid connected solar system?
A grid connected solar system is one that's physically linked to the national electricity grid. This is the most common setup for UK homes. It means you can export surplus electricity and import from the grid whenever your panels aren't generating enough.
To connect to the grid legally, your installer must notify your Distribution Network Operator (DNO). For most systems up to 3.68kW, this is a simple G98 notification. Larger systems require a G99 application, which can take six to twelve weeks to approve.
OVO handles all DNO notifications and applications as part of your installation. You don't need to contact your DNO directly.
Does adding a battery change how the grid connection works?
It doesn't change the connection itself, but it does change how much you interact with the grid day to day.
Without a battery, surplus electricity exports to the grid immediately. With a battery, that surplus charges your battery first. You then draw from the battery in the evening instead of importing from the grid.
| Setup: | Grid imports: | Grid exports: | SEG income: | Annual bill saving (est.): |
|---|---|---|---|---|
| Solar only | Typically higher at night and in winter | High on sunny days | £150 to £250 | £400 to £600 |
| Solar and battery | Typically lower, mainly in winter | Low, battery fills first | £50 to £75 | £700 to £900 |
The SEG income looks lower with a battery. But that's not the full picture. A battery means you use more of your own solar electricity, instead of buying it from the grid. And saving on your bills is worth roughly twice as much per unit as exporting. So overall, you end up better off.
Quick answers
Do I need planning permission to connect solar to the grid?
In most cases, no. Domestic solar installations are permitted development in England, Scotland, and Wales. Listed buildings and some conservation areas are exceptions. Your installer will confirm what applies to your property.
Who pays for the grid connection?
For residential solar, the grid connection is included as part of your installation. There's no separate charge to connect to the grid for systems under 3.68kW. Larger systems requiring a G99 application may involve a DNO fee, which OVO will flag in your quote.
What happens to my solar system during a power cut?
Grid connected solar systems automatically switch off during a power cut. This is a safety requirement to protect engineers working on the grid. If you want backup power during outages, you need a battery with islanding capability. Not all batteries offer this, so if this is something you want, check before you buy.
Can I go completely off grid with solar panels?
Technically yes, but it's not practical for most UK homes. You'd need a very large battery and lots of solar panels to cover winter nights and cloudy stretches. Most households are better off staying connected to the grid and using it as a backup rather than trying to disconnect from it entirely.
Get a free solar quote from OVO
Every home is different, so the best way to understand what a grid connected solar system would generate and save for you is to talk to us directly. OVO's team will take a look at your home and give you a straight answer.