Plug in solar question

Bluefairie56

yes I know it’s not legal yet but it’s still a query.

Say you have a solar panel in your garden, this is plugged into an inverter which is plugged into the home via a socket. Let’s again say that the panel is in total sunshine all day and creates 500 w of solar energy which shows on the inverter. So in the house u put kettle on, washing machine etc and you use total amount of 700 w electric on that day. If there is not a storage/ battery facility connected to panel then as it’s plugged into the grid th3m doesn’t it go to there? For my house energy usage of 700 w this is coming from plugged into things in the house so what has happened to the solar energy the panel created. I probably have not explained it very well at all but I don’t know how that energy I created is used.

paul991

The grid gets it for free

debitcardmayhem

Have a look here https://forums.moneysavingexpert.com/discussion/6549184/plug-in-solar#latest

a long discussion here.

Qyburn

https://forums.moneysavingexpert.com/discussion/6669628/plug-in-solar-question

Think of it as a balance, the solar inverter, the grid and your house electrics all connected together. Without a battery whatever comes out of the inverter serves the house and the grid makes up the difference either way.

Solar 500W, house using 700W, means 200W drawn from grid.

Solar 500W house using 200W, means 300W gets exported to the grid

sheenas

https://forums.moneysavingexpert.com/discussion/6669628/plug-in-solar-question

First it’s perfectly legal as long as you hardwire it into the grid and not use a plug. A fused spur will do the job.

If the panels produce electricity over above what the house is using the surplus goes into the grid. To stop this happening you need a power monitor (clamp). You not supposed to export into the grid without complaining a g98 application. So using a clamp is a good idea.

The regulations have not come out to allow true plug in solar/battery which may be complete this year. In the mean time the hard wire solutions works.

Additionally there are debates going on about RCDs and other technical considerations, but we will see what they come up with.

Qyburn

https://forums.moneysavingexpert.com/discussion/comment/82010508#Comment_82010508

First it’s perfectly legal as long as you hardwire it into the grid and not use a plug. A fused spur will do the job.

There's a lot more to it. To be compliant it needs to be connected on the supply side of all load carrying final circuit protective devices. RCD (if needed) should be type A, F or B and not shared with other circuits. Protective device needs to be bidirectional and also disconnect both L and N. Inverter needs to be type approved, conform to G.98. The installation m ust be declared to the DNO.

Heedtheadvice

Yes your excess is exported as posted above and as Qyburn adds it is formally not as straight forward as one might imagine nor is balancing generation to consumption. It will be though that although generation will be a lot less overall than might be expected from a balcony system you will make more use of that you generat than what larger simple systems achieve so provably quite cost effective.

But on you basic question a bit of clarification may help understanding

The power at any one time is measured in Watts (W) or in the thousands of them kW for higher powered devices such as heaters kettles etc

Over time that energy used is conveniently measure in thousands of Watts over every hour. So a 1kW power heater on for 1 hour continuosly is an energy of 1kilowatt hour (1 kWh ).

So let's assume your solar panels generate 500 Watts continuously over a 10 hour summer day that is an energy of 5kWh.

Assume your only device in the day is a 2kW washing machine and it runs a demanding cycle and heats for 30 minutes in the cycle ( a bit extreme) it uses 1kWh energy.

However at any moment in that heating time the solar power is just 500Watts so it is insufficient to provide the 2 kW needed for heating. The rest ( 1.5kW) comes from the grid which you still purchase.

Although your energy consumed by the wash (1kWh) is far less than the solar energy generated over the day(5kWh) you have not generated sufficient power at the time it is needed for washing.

Assuming the wash is the only power required in the day the rest of the time solar generates more power than needed and it gets exported to the grid.

That is an explanation of a simple case where instantaneous solar generation does not match instantaneous consumption. At times solar exceeds consumption and other times does not meet consumption.Over time the energy produced by solar generation exceeds that consumed by a factor of five over the day ....but you still need to buy some energy from the grid.

The simple case is complicated as the generation is not necessarily continuous ( it is not always blazing sunshine) and generally peaks around mid day and is less in cloud and your consumption varies too., ( plus lots more variables)

A saving grace is that there are usually often other appliances using power intermittently such as fridges and small devices that will consume some of that solar excess and the balcony purchase cost is small so as to make savings worthwhile even though higher power devices needs are not fully met.

In more expensive non balcony systems there is often greater generation power so that covers more consumption. Generation matching demand ( an ideal possibly) is still hardly ever achieved.

Properly qualified solar system generation excess can allow receipt of payment for that excess exported to the grid under the SEG scheme. That is unlikely to apply to balcony solar IMHO.

Battery storage stores generation power to help supply the times it is needed

NedS

In more expensive non balcony systems there is often greater generation
power so that covers more consumption. Generation matching demand ( an
ideal possibly) is still hardly ever achieved.

For reference, with a 3.6kWp system, without battery storage we were only ever able to consume ~33% of power generated in summer, and that is with us at home all day to take advantage.

Modelling a 0.8kWp solar array ('plug-in solar') on PVGIS predicts 820kWh generation per year, assuming optimised location (easier when not roof mounting, but there may be more shading from lower mounting). For someone on SVR, this may be worth around £200/year at current prices, if you were able to use 100% of the generation. If we assume 50% consumption due to the smaller system size, this drops to £100/year so maybe a 4 year payback on a £400 purchase price.

Winter may average 1kWh per day whilst summer should average 3kWh/day.