What percentage of PV energy is usable?

Meatballs

Well this thread certainly went off on a (interesting) tangent 😅

gabitzul

mickyduck55 said:

Thanks to a member of this forum I have a Pi that decides how much power I need to import overnight based on the solar forecast, this is not perfect as we all know that forecasting the weather is not yet an exact science.

Hi Micky, I have a PI as well and can't make much sense of the Node-Red stuff (I assume this is what you are using?). Do you by any change have a tutorial, or the source files? The FaceBook page for Sofar ME3000SP has info as well but it's so many versions, it's confusing. I am using a Sofar and have the RS485 interface etc.

Thanks in advance and sorry to hijack the thread.

gabitzul

Meatballs said:

Well this thread certainly went off on a (interesting) tangent 😅

Sorry, I am not helping, am I?...

JKenH

Petriix said:

JKenH said:

Solarchaser said:

JKenH said:

Solarchaser said:

Those who have batteries can play a good role in decarbonising the grid as most will be on a time of use tarriff, and so will be discharging the batteries to cover the house load when the grid is dirtiest and most expensive, and also refilling the batteries when the grid is greenest.
Win win really.

Not really over the last week or so. Any charging of batteries whether from your own solar or the grid has contributed to the amount of gas generation required because of the efficiency losses during the charging and discharging cycles. 10-20% more energy will have been needed from the grid than if you had simply powered the devices from live generation. It just isn’t possible for the grid to ramp up renewable energy to charge your batteries or car at night. Perhaps the proportion of gas in the grid is lower but you are adding marginal load. The only time that it is going to come from renewables is when we are curtailing wind.

There is a tendency to confuse cheap electricity with clean electricity.

I'm tempted to say speak for yourself, but instead I'll remind you once again that the generation in Scotland is alot more green than Middle England.
Mid day today southern Scotland was by Scottish standards pretty dirty, i seen 180g on eso app, so the fact I was using solar plus batteries to fill the leaf (for the wifes work tonight) rather than charging from the grid makes them somewhat more green.

Now we are under 100g, its definitely greener to charge the batteries just now, which will be much more likely to be excess wind rather than getting them to turn on more gas middle of the day, and we seem to be supplying quite a bit of Northern England's power too which brings the North of England a bit cleaner.
Certainly better than getting supplied by middle England which is unfortunately burning well over 300g (dont even look at east midlands)including rather a large amount of coal 😥

Which is not to say my whole motivation for batts was being green, it wasn't.
However charging batts when there is much less strain on the grid, and so much less likely to be coming from dirty coal can only be a good thing surely??

It is no surprise that the East Midlands generation is so dirty as that is where the coal fired stations are located. It is very virtuous of you Scots to consume such green electricity when those of us in the East Midlands are so dirty in our consumption. 

I am sure, however, those of you living in the Central Belt were grateful when you put the kettle on for a cuppa this morning that the whole grid is interconnected so you could enjoy the contribution from coal in the East Midlands. At 7am today renewables (which I presume are the mainstay of Scotland’s clean generation) were providing just 0.42GW of the total UK demand of 30 GW, and probably around a tenth of consumption in the Central Belt. 

Edit: it was interesting to see that in the early hours of yesterday North Scotland’s grid was 30 times dirtier than that of the North East.

https://carbonintensity.org.uk/

The grid is (unfortunately) less 'interconnected' than you would hope. There are severe limitations on getting the green generation from the outlying areas to where the demand is. This is something that is improving and the subject of significant investment.

That may be the case when looked at from the point of view of getting renewables from remote locations to population centres but the flow from the East Midlands and Yorkshire where the large coal fired stations are based has been established for decades. As long ago as the 1960s the Midlands had the capacity to send 6GW to the Home Counties and that was before the construction of the 400v Supergrid. That is why there are so few power stations in London. 

I would be intrigued to know though why the North East was so clean.

silverwhistle

JKenH said:

As @Exiled_Tyke pointed out adding solar can cause us to be more wasteful with the use of items such as tumble dryers because the electricity is free to us, (particularly if we are on deemed export).

Having bought the panels, solar energy is free and I feel I am wasting it if I don’t use as much of it as possible. I think this is what often drives people to get home batteries even if they aren’t actually economic. You’ve paid for it so you don’t want to  waste it.

I think the modal 'can' in the first paragraph is true in some cases, but my gut feeling is that people who have installed PV tend to be more aware, and certainly having solar helps that awareness and understanding. I certainly haven't bothered to get a tumble dryer!

As for the drive for batteries: that motivation is probably true, I'm exporting as I type which grates a bit but I might go and turn on an oil-filled rad in my cooler lounge. I wonder though if the difference between the new day and night rates that we can see in tariffs such as Octopus Go (something like 34p/7.5p) make for better arbitrage opportunities and hence easier to justify batteries economically?

One interesting post I saw on an EV forum talked about using the battery to assist in charging the car as it allowed for granny charging when there was not quite enough PV on its own to avoid being charged at peak rate. This avoided the need for a specialised diverter and made full use of the battery.

Martyn1981

silverwhistle said:

One interesting post I saw on an EV forum talked about using the battery to assist in charging the car as it allowed for granny charging when there was not quite enough PV on its own to avoid being charged at peak rate. This avoided the need for a specialised diverter and made full use of the battery.

That's definitely a good plus for a battery. Last 'summer' (better 6 month PV period) we charged the BEV's almost exclusively off PV via the granny charger, but of course would have used a small bit of import due to fluctuating generation. This year, with prices having jumped so much, any and all import, perhaps when clouds cross the sky, will cost even more. So a battery buffering that PV and demand would certainly add some value, and the same would apply to small heatpumps when spare gen is bouncing around the 500W(ish) mark.

Nice over the air update from Tesla last Xmas now means we can select the charging amps (5 to 32), so I've now been able to charge as low as 1.2kW's, which has helped, and also lazily means I don't even need to get the granny charger out of the frunk. Also useful recently for my wife charging at her parents where she had to use an extension lead, but at 5A's no plugs, leads nor sockets got hot. I'd assume that most BEV manufacturers will start to offer this soon, maybe some already do?

Solarchaser

JKenH said:

Solarchaser said:

JKenH said:

Solarchaser said:

Those who have batteries can play a good role in decarbonising the grid as most will be on a time of use tarriff, and so will be discharging the batteries to cover the house load when the grid is dirtiest and most expensive, and also refilling the batteries when the grid is greenest.
Win win really.

Not really over the last week or so. Any charging of batteries whether from your own solar or the grid has contributed to the amount of gas generation required because of the efficiency losses during the charging and discharging cycles. 10-20% more energy will have been needed from the grid than if you had simply powered the devices from live generation. It just isn’t possible for the grid to ramp up renewable energy to charge your batteries or car at night. Perhaps the proportion of gas in the grid is lower but you are adding marginal load. The only time that it is going to come from renewables is when we are curtailing wind.

There is a tendency to confuse cheap electricity with clean electricity.

I'm tempted to say speak for yourself, but instead I'll remind you once again that the generation in Scotland is alot more green than Middle England.
Mid day today southern Scotland was by Scottish standards pretty dirty, i seen 180g on eso app, so the fact I was using solar plus batteries to fill the leaf (for the wifes work tonight) rather than charging from the grid makes them somewhat more green.

Now we are under 100g, its definitely greener to charge the batteries just now, which will be much more likely to be excess wind rather than getting them to turn on more gas middle of the day, and we seem to be supplying quite a bit of Northern England's power too which brings the North of England a bit cleaner.
Certainly better than getting supplied by middle England which is unfortunately burning well over 300g (dont even look at east midlands)including rather a large amount of coal 😥

Which is not to say my whole motivation for batts was being green, it wasn't.
However charging batts when there is much less strain on the grid, and so much less likely to be coming from dirty coal can only be a good thing surely??

It is no surprise that the East Midlands generation is so dirty as that is where the coal fired stations are located. It is very virtuous of you Scots to consume such green electricity when those of us in the East Midlands are so dirty in our consumption. 

I am sure, however, those of you living in the Central Belt were grateful when you put the kettle on for a cuppa this morning that the whole grid is interconnected so you could enjoy the contribution from coal in the East Midlands. At 7am today renewables (which I presume are the mainstay of Scotland’s clean generation) were providing just 0.42GW of the total UK demand of 30 GW, and probably around a tenth of consumption in the Central Belt. 

Edit: it was interesting to see that in the early hours of yesterday North Scotland’s grid was 30 times dirtier than that of the North East.

https://carbonintensity.org.uk/

Thank you for recognising my virtuosity 🙏😇,  I wasn't using any of that dirty Midlands coal... as I was on batteries which were charged from the sun yesterday 😅

Scotland used to have dirty coal power stations too, and not that long ago either, there was just a lot more political pressure to get rid of them quicker up here.

Ps. I thought you were north east, not Midlands as its the North East that has the worst charger network for EV's

Edit, chased down what you had said about Monday morning and you are absolutely right, early on Monday Scotland was indeed getting a helping hand from South of the border, thanks guys 👍


I think it's fair to say we repaid the favour after about 7:30am.

(We, as if I had anything to do with it 🤣🤣)

Solarchaser

Martyn1981 said:

silverwhistle said:

One interesting post I saw on an EV forum talked about using the battery to assist in charging the car as it allowed for granny charging when there was not quite enough PV on its own to avoid being charged at peak rate. This avoided the need for a specialised diverter and made full use of the battery.

That's definitely a good plus for a battery. Last 'summer' (better 6 month PV period) we charged the BEV's almost exclusively off PV via the granny charger, but of course would have used a small bit of import due to fluctuating generation. This year, with prices having jumped so much, any and all import, perhaps when clouds cross the sky, will cost even more. So a battery buffering that PV and demand would certainly add some value, and the same would apply to small heatpumps when spare gen is bouncing around the 500W(ish) mark.

Nice over the air update from Tesla last Xmas now means we can select the charging amps (5 to 32), so I've now been able to charge as low as 1.2kW's, which has helped, and also lazily means I don't even need to get the granny charger out of the frunk. Also useful recently for my wife charging at her parents where she had to use an extension lead, but at 5A's no plugs, leads nor sockets got hot. I'd assume that most BEV manufacturers will start to offer this soon, maybe some already do?

Finally got the zappi installed 2 weeks ago, and so far managed to put in 146kwh of sun powered freeness into the two cars, which has been great, and about a quarter of that has been with full batteries and marginal generation using the batteries to part charge the cars topping up the sun.
It's worked particularly well as the wife's shifts have meant her leaving in the early afternoon sometimes, so I can blast the charge through to get the leaf to a decent level and when she unplugs the leaf, the solar tops up the batteries again.

Solarchaser

Meatballs said:

Well this thread certainly went off on a (interesting) tangent 😅

Ahh yeah, they tend to do that on her sometimes. 
Some points overlap with others, and some folk like to go off on a tangent, I blame Ken mostly, and maybe Martyn, and probably silverwhistle and Petrix.
But definitely not me, obviously *innocent whistle* 😇

Petriix

Solarchaser said:

Meatballs said:

Well this thread certainly went off on a (interesting) tangent 😅

Ahh yeah, they tend to do that on her sometimes. 
Some points overlap with others, and some folk like to go off on a tangent, I blame Ken mostly, and maybe Martyn, and probably silverwhistle and Petrix.
But definitely not me, obviously *innocent whistle* 😇

Are we now going off on a tangent about going off on a tangent? I fully accept responsibility for my digression.