Last reviewed: 5 September 2026. This page is about behaviour, not
hardware — everything on it costs nothing and applies to any plug-in kit. Appliance consumption figures
are typical published ranges, not measurements of our own, and we say so where they appear. Electricity
figures use the Ofgem price cap for 1 October to 31 December 2026: 26.32p per kWh.
If you own a plug-in solar kit, this is the page that puts money in your pocket. Not because of any
trick, but because of an unusual structural fact: exported units earn you nothing, so the only thing
that determines your return is what share of generation you consume at the instant it is produced. That
share is entirely within your control, and most households leave half of it on the table.
Moving a typical household from 50% to 80% self-consumption on an 800 kWh-a-year kit is worth about
£63 a year, every year, for the life of the panels. It requires no purchase and no rewiring. It
requires knowing when the sun is on your panels and putting things in its way.
The one thing to understand first
Solar output is not a flat block from dawn to dusk. It is a hump. On a clear day an 800 W kit spends
perhaps four hours near its ceiling either side of solar noon, and produces very little at the edges.
On an overcast day it produces a fraction of its rating all day and never reaches the ceiling at all.
That shape has a direct consequence: the useful window is roughly 10am to 4pm in summer, and closer
to 11am to 2pm in winter. Everything below is about moving load into that window.
The second consequence is less obvious. Your kit can supply at most 800 W. Any appliance drawing
more than that is being part-supplied by solar and part-supplied by the grid — which is still a saving,
but running two 800 W loads at once does not double your benefit. Sequential is better than
simultaneous.
What each load is worth, ranked
The table below ranks the common opportunities by how much you can realistically move. Consumption
figures are typical published ranges for UK domestic appliances, not our own measurements.
| Load | Typical energy per use | Realistic shift | kWh moved per year | Annual value |
|---|---|---|---|---|
| Immersion heater / electric hot water | 2 – 3 kWh per heating cycle | Daily, in summer | 200 – 350 | £53 – £92 |
| Tumble dryer | 2 – 4 kWh per cycle | 3 loads a week | 150 – 300 | £39 – £79 |
| Washing machine | 0.5 – 1.5 kWh per cycle | 4 loads a week | 100 – 300 | £26 – £79 |
| Dishwasher | 0.8 – 1.5 kWh per cycle | 5 cycles a week | 200 – 390 | £53 – £103 |
| Fridge and freezer | Continuous, 0.7 – 1.5 kWh a day | Already daytime; nothing to shift | Baseload — soaks up surplus for free | Included by default |
| E-bike battery | 0.4 – 0.6 kWh per charge | 3 charges a week | 60 – 95 | £16 – £25 |
| Laptops, tablets, phones, power tools | Small individually | All of it | 50 – 120 | £13 – £32 |
You cannot claim every row — an 800 kWh kit only has 800 kWh to give, and the point of the table is
to show you which levers are big, not to add them up. Hot water and the dishwasher are the two that
change the answer for most households. Phone charging is a rounding error that people talk about far
more than it deserves.
The tactics, in order of value
1. Move hot water into the middle of the day
If you heat water electrically — an immersion in a cylinder, or an electric shower cylinder — this
is the largest single lever available to a plug-in kit, because hot water is stored energy. The
cylinder is a battery you already own. Set the timer to bring the immersion on at around 11am rather
than overnight or in the evening.
Two cautions. An immersion element typically draws 3 kW, well above your kit’s 800 W ceiling, so
solar covers roughly a quarter of it while it runs — a genuine saving, but not a free tank. And if you
are on a cheap overnight tariff, overnight units may already be cheaper than the daytime rate you are
displacing, in which case this tactic is worth less or nothing. Check your own rates before changing
anything.
2. Put every timed appliance on a midday delay
Dishwashers, washing machines and most modern tumble dryers have a delay-start function. Load them
in the evening, set the delay so the cycle runs from about noon. This is the highest-value ten seconds
of button-pressing available to a solar owner, and it works whether or not anyone is home.
Stagger them. A washing machine on its heating phase and a dishwasher on its heating phase at the
same moment are drawing perhaps 4 kW between them, of which your kit supplies 800 W. Run them back to
back and each gets a larger share.
3. Use a plug-in timer for everything that has no timer
A £10 mechanical or digital plug timer handles the dehumidifier, the towel rail, the water butt
pump, the pond pump, the electric heated airer. Anything that runs for a fixed period and does not care
when.
Do not run your solar kit through a timer, an extension lead or an adapter. The Interim Product Specification prohibits extension leads,
multiway adaptors, travel adaptors and RCD adaptors for the microgenerator itself. Timers belong on the
loads, never on the generator. See is a plug-in solar
extension lead safe.
4. Charge everything in daylight
E-bike and e-scooter batteries, cordless tool batteries, laptops, the robot vacuum, the handheld
vacuum. Individually small, collectively a hundred kWh a year in a well-equipped household, and all of
them are perfectly happy to charge at 1pm instead of 11pm.
If you have an electric car on the drive during the day, that is a different scale of opportunity —
but only if your charger can be set to a very low current. A 7 kW charger pulling from an 800 W kit
simply imports the other 6.2 kW. Some chargers offer a solar-matching mode; most domestic ones set to
their minimum current still draw far more than a plug-in kit produces.
5. Let the fridge do its work
Your fridge, freezer, router, boiler pump and standby loads together typically draw somewhere in the
region of 150 to 300 W around the clock. That baseload is the reason self-consumption is never zero: it
quietly absorbs a slice of every daylight hour without anyone doing anything. It is also the reason an
800 W kit suits British homes — the ceiling is a decent match for what a house draws when nobody is
actively using it.
A worked day
| Time | Unmanaged household | Managed household |
|---|---|---|
| 07:00 | Kettle, toaster, shower — kit producing almost nothing | Same. Nothing to do here. |
| 09:00 | House empty. Baseload only. | Dishwasher delay-start set for 12:00 the night before. |
| 11:00 | Exporting. | Immersion timer brings hot water on. |
| 13:00 | Exporting. | Washing machine runs on delay start. |
| 15:00 | Exporting. | E-bike and tool batteries on a plug timer. |
| 18:00 | Everyone home. Oven, kettle, laundry — all imported at full rate. | Laundry already done. Hot water already hot. |
| Day total | Roughly half of generation used | Roughly four-fifths used |
Nothing in the right-hand column costs money. It is the same appliances doing the same work at a
different hour.
What not to bother with
- Buying more panels to fix low self-consumption. It makes the problem worse: more
generation at the same midday hours you were already exporting. See the payback page. - A battery bought solely to soak up plug-in surplus. The numbers do not work at
this scale, and a plug-in kit cannot legally contain one. See can I add a battery to plug-in solar. - Chasing the last 5%. Living around your panels — cooking at odd hours, refusing
to boil a kettle after four — trades quality of life for pennies. Set the timers and get on with your
life.
Frequently asked questions
Is it worth it on a cloudy day?
Yes, at a reduced level. A kit still produces meaningfully in bright overcast conditions — enough to
cover baseload and part of a wash cycle.
What if I am on a time-of-use tariff?
Then compare rates before shifting. Displacing a 7p overnight unit with a solar unit saves 7p;
displacing a 26.32p daytime unit saves 26.32p. Shift loads out of the peak window first.
Does any of this apply to a rooftop system?
The tactics do, but the urgency does not: a rooftop system can be paid for export under the Smart Export Guarantee, so surplus is worth something
rather than nothing. See does plug-in solar export to
the grid.
Sources.
Ofgem, price cap unit rates and standing charges ·
DESNZ, plug-in solar interim product specification v2.0 ·
Ofgem, Smart Export Guarantee.
Appliance consumption figures are typical published ranges, labelled as such; all savings are our own
arithmetic from the stated assumptions. See editorial
methodology.