Solar PV + Battery quotes

Solarchaser

Page 10 of the installation manual suggests you can set a minimum threshold.
I tried to attach it here, unsuccessfully,  but if you Google solic 200 installation manual, its like 3rd result. 

A link, no, pretty sure it was on the navitron forum though.

Petriix, that may be the case where you live, certainly isn't the case in Scotland. 

mickyduck55

Solarchaser said:

Page 10 of the installation manual suggests you can set a minimum threshold.
I tried to attach it here, unsuccessfully,  but if you Google solic 200 installation manual, its like 3rd result. 

A link, no, pretty sure it was on the navitron forum though.

Petriix, that may be the case where you live, certainly isn't the case in Scotland. 

I see the instructions thanks but seems even worse to me.. set threshold and any power above that sent to immersion?  That is also a very old system / manual, my more modern one has no mention of DIP switches but guess the newer boxes are the same inside.  Let me know how you get on cheers

Solarchaser

Yeah so if it sees 500w and your threshold is 200w, then 300w gets sent to element, but since there's still 200w of export. Batteries won't discharge to run element.

Seems a decent solution to me, but its likely to be 6 months before I can put it to the test.
I'll certainly report back then.

Petriix

Solarchaser said:

Petriix, that may be the case where you live, certainly isn't the case in Scotland. 

That's a snapshot on a windy day. The average CO² per kWh for the UK grid in 2019 was significantly higher than the estimated average CO² per kWh for a gas boiler (roughly 260g vs 220g). However, it's not reasonable to equate a tiny export from a micro-generation installation with the whole grid.

The vast majority of short-term demand is met by burning gas because those are the most dynamic power stations. You can't just spin up more wind farms (or nuclear output) whenever you want them. As we develop more grid-scale battery storage the picture will change but that's still some way off.

I understand why self-consumption is appealing. In the case of hot water diverters, however, it is objectively a false economy. A myth perpetuated by the installers to increase their sales.

Solarchaser

That was a snapshot of... the time I posted.
The UK grid is very different from top to bottom.

You can make your point in the Midlands if you want, doesn't really work in Scotland.

But yeah. You crack on pal 👍

mickyduck55

Solarchaser said:

Yeah so if it sees 500w and your threshold is 200w, then 300w gets sent to element, but since there's still 200w of export. Batteries won't discharge to run element.

Seems a decent solution to me, but its likely to be 6 months before I can put it to the test.
I'll certainly report back then.

So I think this would heat the water BEFORE charging the batteries?  What I think is ideal is batteries fully charged before anything sent to immersion

Martyn1981

Petriix said:

That's a snapshot on a windy day. The average CO² per kWh for the UK grid in 2019 was significantly higher than the estimated average CO² per kWh for a gas boiler (roughly 260g vs 220g). However, it's not reasonable to equate a tiny export from a micro-generation installation with the whole grid.

Hiya. Just a point, but the CO2 intensity of the grid is falling fast, with a target of ~100g/kWh by 2030. But more importantly it's worth considering that a diverter will mostly be used during the non-heating months when PV generation is higher. At those times the gas boiler is far less efficient as it's not running the heating, and all of the heat lost from the boiler and pipework (within the thermal envelope of the property) is no longer a benefit to the household, so you are most likely looking at a halving of the efficiency and a doubling of the carbon intensity.

Also at the times of diversion there is most likely a national rise in solar generation (and export) meaning that a useful diversion has value long term as a means of RE storage.

I think it's worth taking the seasonal issues of a diverter into account if comparisons are to be drawn.

JKenH

Martyn1981 said:

Petriix said:

That's a snapshot on a windy day. The average CO² per kWh for the UK grid in 2019 was significantly higher than the estimated average CO² per kWh for a gas boiler (roughly 260g vs 220g). However, it's not reasonable to equate a tiny export from a micro-generation installation with the whole grid.

Hiya. Just a point, but the CO2 intensity of the grid is falling fast, with a target of ~100g/kWh by 2030. But more importantly it's worth considering that a diverter will mostly be used during the non-heating months when PV generation is higher. At those times the gas boiler is far less efficient as it's not running the heating, and all of the heat lost from the boiler and pipework (within the thermal envelope of the property) is no longer a benefit to the household, so you are most likely looking at a halving of the efficiency and a doubling of the carbon intensity.

Also at the times of diversion there is most likely a national rise in solar generation (and export) meaning that a useful diversion has value long term as a means of RE storage.

I think it's worth taking the seasonal issues of a diverter into account if comparisons are to be drawn.

I would agree with that. I can go for 6 months without turning on the boiler in summer even  if after a run of bad days I have to bang in half an hours E7 water heating. It just isn’t worth heating all the boiler components and pipework up for a few minutes hot water. In winter I don’t bother with the diverter much at all preferring to put what PV we have into the ASHPS and heating the water by E7 on mild days and the boiler on cold days when the central heating is on. I have an oil fired boiler so the maths vary from year to year. This year we would have expected to be using more oil as it is relatively cheap (about 3p/kWh) but if I eventually get on to Octopus Go the maths may change again. Since I got an EV it is better for me to top that up with solar and heat water by E7 as our main hot water usage is around 8am.

Solarchaser

mickyduck55 said:

Solarchaser said:

Yeah so if it sees 500w and your threshold is 200w, then 300w gets sent to element, but since there's still 200w of export. Batteries won't discharge to run element.

Seems a decent solution to me, but its likely to be 6 months before I can put it to the test.
I'll certainly report back then.

So I think this would heat the water BEFORE charging the batteries?  What I think is ideal is batteries fully charged before anything sent to immersion

Yeah fair point.
For my own outlook, I have more solar than the diverter could handle, I just dont want the batteries discharging into the diverter when sun goes down.
Perhaps having a timer run between say 11am and 4pm for the diverter?
Clearly more thought required on this. 
Thanks for your input 👍

iConnzz

Hello don't think you've had a response re the DNO yet. For systems that size you will certainly need a G100 full scope application and this needs to be done before the install is commissioned. This put simply is all due to your theoretic feedback to the grid. You can feedback 3.68kW under a simple G98 application which is more of a formality to obtain for your SEG.  Please question them further on the DNO side of things.