Disconnecting from the electricity network entirely. It is a real thing that some properties do, and for the large majority of British households it is a worse deal than staying connected.
Here is the honest version.
Why it costs so much more than people expect
An off grid system has to cover your worst case, not your average.
A grid-connected system can be sized for a normal day, because the grid covers the gaps. An off grid system has to get you through a still, overcast week in December when the panels produce almost nothing and you cannot buy your way out.
That means:
- Far more generation than a grid-tied system of the same household
- Far more storage, sized for days of autonomy rather than one evening
- A backup generator for the worst stretches, plus fuel and maintenance
- More robust equipment, because a failure is not an inconvenience, it is no electricity
The cost is not a little higher. It is a different order of thing.
The British problem specifically
Solar in the UK is strongly seasonal. A December day may produce a tenth of what a June day produces.
An off grid system in Britain therefore has to be sized around a period when its main generator produces very little, which is why every serious UK off grid setup includes either a generator, a wind turbine, or a great deal more capacity than seems sensible in summer.
In a sunnier country with less seasonal variation the sums are far more forgiving. Do not read advice written for Australia or the southern United States and assume it transfers.
When it is genuinely the right answer
When connecting to the grid would cost more This is the real case. A remote property facing a five-figure or six-figure connection quote from the network operator may find an off grid system cheaper than the cable.
If that is your situation, get the connection quote first. It is the number the whole decision turns on and people often assume it without asking.
Outbuildings, workshops and stables where running a supply is awkward and the load is small.
Genuinely remote properties with no realistic connection.
When it is not
Wanting independence from suppliers Understandable, and there are cheaper ways to get most of the benefit. Solar and a battery on a time-of-use tariff gets you a long way towards insulating yourself from prices, at a fraction of the cost, and you keep the ability to sell your surplus.
Wanting resilience in a power cut That is backup, not off grid, and it is much cheaper. See solar in a power cut.
Wanting the lowest bills Staying connected almost always wins, because you can sell surplus and buy cheaply overnight.
What you lose by disconnecting
- Export income. No Smart Export Guarantee without a grid connection. See export payments
- Cheap overnight electricity. No time-of-use tariff either
- The ability to size for a normal day rather than the worst one
- Simplicity. An off grid system needs more attention, more maintenance and more understanding from its owner
And disconnecting an existing supply is not always easily reversed. Getting reconnected later can mean paying for a new connection.
If you are still interested
- Get a grid connection quote from your network operator first, even if you expect it to be high. It is the number the decision turns on
- Get a proper load assessment, honestly done. Off grid design lives or dies on knowing what you actually use
- Budget for a generator and its running costs
- Find an installer who has genuinely done off grid work. It is a different discipline from grid-tied solar and most installers do not do it
- Consider a hybrid approach: stay connected, but size solar and storage so you import very little. Most of the benefit, far less of the cost and risk