How solar works
From daylight on your roof to electricity in your home
A plain explanation of what generates, what your home uses, what leaves for the grid, and the connection rules that sit behind all of it.
From daylight to electricity
Solar panels convert daylight into direct current electricity. Output rises and falls with the light reaching the panel surface, which is why generation follows a curve through the day and a season through the year. Heat is not what drives it — panels work throughout the UK winter, just with fewer daylight hours to work in.
An inverter converts that direct current into the alternating current your home uses, and it is also where generation is measured and reported. Its capacity relative to the array is a deliberate design choice, not simply a match to the panel total.
What happens in your home
Generated electricity is used by whatever is running at the time: the fridge, appliances, hot water, an EV charger. Your home draws from the grid only for whatever generation does not cover. There is no switching over — the two supplies simply blend, which is why the effect shows up as a smaller bill rather than as a separate credit.
The order electricity is used in
- Household demand is met from generation first
- Surplus charges a battery, where one is fitted
- Remaining surplus is exported to the local network
- Any shortfall is imported from your supplier as normal
Through the day
Generation, demand and storage over 24 hours
Midday
Generation is at its highest while the house is often using less. The surplus charges the battery instead of being exported.
Evening
Generation falls as household use rises. The battery supplies stored electricity, so less is bought from the grid.
Through the day
Daylight
Daylight reaches the panels on your roof.
Panels + inverter
DC generation is converted to usable AC.
Your home
Your home uses whatever it needs first.
Battery
Surplus can charge storage instead of exporting.
Evening and overnight
Battery
Stored electricity is released after dark.
Your home
Evening use is met from storage where possible.
Grid
The grid covers anything still needed.
Whether surplus generation is stored or exported depends on your system design, battery capacity and how your home uses electricity at the time.
Export and the grid
Surplus generation flows out into the local distribution network. If you are on an export tariff, your supplier pays for it, usually at a lower rate than you pay to import. That gap between import and export rates is the reason storage and load shifting are worth considering.
G98, G99 and G100 in plain English
Your Distribution Network Operator owns and operates the cables and substations in your region — separate from the supplier that bills you. Because your system exports into that network, the equipment has to be notified to, or approved by, the DNO under the industry connection rules.
G98 covers smaller installations that can be connected and then notified. G99 covers larger installations, which need an application and approval before connection. G100 describes an approved arrangement where equipment actively limits how much a site can export, which can allow a larger system on a constrained connection.
Which route applies depends on inverter capacity, whether your supply is single or three phase, and any generation already installed. Until those are confirmed we treat the position as to be confirmed rather than implying an approval that does not exist yet.
Monitoring and performance
Monitoring shows generation, household consumption and — with a battery — charge and discharge. It is the practical way to confirm a system is performing as designed, because a gradual fall in output is far easier to spot in the data than on a bill.
How solar works FAQs
How much electricity can panels generate?
Generation depends on system size, orientation, pitch and shading. As a broad UK guide, each installed kilowatt-peak (kWp) of well-oriented roof-mounted solar typically produces somewhere in the region of 750–1,000 kWh a year. Your assessment uses solar irradiance data for your specific roof faces rather than that generic range, which is why two neighbouring houses can return different figures.
Do panels work in winter?
Yes. Panels generate from daylight rather than heat, so they produce electricity throughout the UK winter — just less of it, because days are shorter and the sun is lower. Expect the strongest output from around April to September and a noticeably lower contribution in December and January. Cold, bright days can actually be very productive, because panel efficiency improves slightly at lower temperatures.
Do I need a south-facing roof?
No. South-facing roofs give the highest annual total, but east and west facing roofs still generate well and shift output towards the morning and afternoon, which often matches household usage better. East/west splits across two slopes spread generation across the day rather than peaking sharply at midday. North-facing slopes are generally not worth using on their own.
What is a DNO?
The Distribution Network Operator is the company that owns and operates the local electricity network in your region — the cables, substations and connections, as opposed to the supplier that bills you. Because solar exports electricity into that network, generation equipment has to be notified to, or approved by, the DNO under the industry connection rules.
What is G98?
G98 is the industry standard covering the connection of small generation equipment. Many domestic installations connect under this route, where the installer notifies the DNO that the equipment has been fitted, commonly within 28 days of commissioning, rather than waiting for prior approval. The relevant limit is based on inverter capacity per phase, not on the number of panels.
What is G99?
G99 covers larger or more complex generation connections, where an application is made to the DNO and approval is granted before the equipment is connected. Domestic projects can fall under G99 when the inverter capacity is above the small-generation threshold, or where there is existing generation or a network constraint. It adds a step to the timeline rather than being a problem in itself.
What is G100 export limitation?
G100 describes an approved arrangement where equipment actively limits how much electricity a site can export to the network. It allows a larger generation or storage system to be installed on a constrained connection, because export is capped by a monitored control scheme. It affects export, not what you can generate and use in the home.
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