What % of your Solar PV generation do you actually use, on average?

ASavvyBuyer

We have had Solar PV for just over two years now and for the last year have been assessing whether the deemed 50% is correct. We have a monitor on our total consumption and use the figures from that to estimate the difference between what we actually import & generate (using the meter readings).

With using a diverter and an Air Conditioner/Heat Pump, we have an average use of just over 40% over the last year. Meaning that nearly 60% is actually being exported.

This has varied over the year, from using below 30% in the Summer to using nearly 90% mid Winter (when we don't get any direct sun & generation is low).

What % do others managed to use of their solar PV generated electricity and if higher, how?

EricMears

Using the Immersun app, I've just looked back for the last couple of weeks and only on a couple of occasions did we export more than 0.5kWh in a day. The exceptions were days when Immersun had reported "HOT"

Because we have a 'HeatBank' (a very large copper cylinder that controls CH & DHW) and can take it up to over 90deg C there aren't many days even in summer when that happens and none at all in the winter.

We are of course also trying very hard to maximise sunny daytime use of washing machine, dishwasher etc as well.

I guess our annual percentage export would be less than 5%.

Martyn1981

Similar here. I don't know export, so have to guess that consumption is about 1,500kWh's out of 4,200-4,500kWh's, so around 33-36%.

With the new ASHP that figure may climb to 40%. Alternatively, with the new SolarEdge system on the ESE system, generation may rise by 10%, and consumption fall (as a percentage), not really sure.

Markj1110

In 2016 I used 63% of total production and so far this year have used 53%. Winter months are the highest with 90% being used in December/January/February. I have a Geo Chorus monitor which I find works very well, although they don't make that model any more. I now have an iboost to fit, so hopefully will see more production used.

treaclepumpkin

We've got an enlighten diverter, that uses any excess to heat the hot water tank.
For 2016 we used 69% of total production, the current year to date is 67%.

The_Green_Hornet

On a nice sunny day like last Sunday my system exported 76.63% of what it generated, whereas on a miserable day such as yesterday it only exported 36.36%.

Looking at historical figures since I installed my Energyhive hub, monthly export percentages have been recorded are as follows:

March - 72.54%
April - 71.16%
May - 68.23%
June - 70.81%
July - 75.24%

Appears that I am a good neighbour.

legoman62

According to wattson anywhere since June 2014 I have made 11951kWh:)
Also says I've used 7834 of them, so 65.5% ish:T

ASavvyBuyer

Martyn1981 wrote: »

Similar here. I don't know export, so have to guess that consumption is about 1,500kWh's out of 4,200-4,500kWh's, so around 33-36%.

Hi Mart,

A cheap and easy way to get a measure of total consumption is by using one of the (what were free from energy suppliers) energy monitors. We use one from E.on which shows current Watts, plus a display that shows kWhs used for previous day, last 7 days and last 30 days. They are available on ebay for about £10.

By having the monitoring clamp round one of the cables feeding power into the distribution board, it provides a measure of our total consumption. By subtracting the readings from the import meter, we can then estimate how much electricity is being provided by solar PV to make up the difference.

EricMears

ASavvyBuyer wrote: »

By having the monitoring clamp round one of the cables feeding power into the distribution board, it provides a measure of our total consumption. By subtracting the readings from the import meter, we can then estimate how much electricity is being provided by solar PV to make up the difference.

Not sure if my distribution board is unusual or ASB's is but that approach certainly wouldn't work for me.

The inverter is connected to a spare way in our distribution board. Very easy to stick a clamp round the SP input but there's nowhere we could easily measure present consumption with a simple clamp. Not only is the mains feed to disboard distorted by not knowing what is arriving along that cable, there's also the possibility that the reading might sometimes show what is being exported along it.

Fortunately, I have an Immersun setup which uses directional clamps so does show what is being used & exported fairly reliably (albeit not 100% accurately).

ASavvyBuyer

EricMears wrote: »

Not sure if my distribution board is unusual or ASB's is but that approach certainly wouldn't work for me.

The inverter is connected to a spare way in our distribution board. Very easy to stick a clamp round the SP input but there's nowhere we could easily measure present consumption with a simple clamp. Not only is the mains feed to disboard distorted by not knowing what is arriving along that cable, there's also the possibility that the reading might sometimes show what is being exported along it.

Our SP feed is not via a spare way on the distribution board; it has its own mini distribution board that connects the mains feed and solar feed together before entering the main distribution board. Therefore, the clamp measures what is actually being used in total by everything connected to the main distribution board.

michaels

Our solar comes into a fuse on the secondary consumer unit and we seperately have a main consumer unit next to the meter so we could not even measure how much the secondary unit circuits use let alone then add in what runs of the primary unit.

WE do know how much is diverted via the iboost and thus the max per day that is normally diverted (we set the tank to 50-60 degrees [lower in summer, more in winter] on the gas with the immersion thermostat at 70 degrees) so we can estimate that up to that number of unused kwh will go into the hot water on any day we generate more than that.

E.G - Energy to tank to heat from 50 degrees to 70 degrees is 10kwh so if we generate 15kwh on a day we will use at least 10kwh of that even if we don't run any thing electrical whilst generating.

However we also use about 7.5kwh per day in our car on average and aim to charge in the day during peak production times so depending on the time of year and weather up to 100% of the car electricity comes form the panels.

So I reckon on our best production days which generate approx 26kwh we probably use at least 10+7 = 17kwh (plus probably 1k of background usage on TVs, PCs, washing machine, iron etc) = 69% and on most days we use a higher percentage as the car uses lots during the highest production period and the iBoost mops up the surplus before and after the car is charged.

Wish I could prove this. One thing I do is to compare import between months with different solar output - I know this is not strictly accurate as usage will vary by some of the same factors that impact generation (more sunshine = less lights on time for example) and will vary over time as appliance usage changes but this should give a view of how much of any change in generation maps to a change in import for example in June we generated 534 units and imported 450 units and in July we generated 482 units (52 less) and imported 486 units (36 units more) so you could conclude that we used 36 of the extra 52 units generated in June - 69%!