On-grid domestic battery storage

joefizz

zeupater wrote: »

Hi

But that's just a silly & unnecessary response to a valid logical observation ... placing a heat source into a room with TRV controlled heating simply results in the TRV cutting out with less heat input, whilst turning the TRV temperature down simply reduces the minimum temperature in the room ... as such, I would have thought the majority would surely recognise the validity of the point made!

HTH
Z

Ok, heres the non silly explanation.
TRVs measure the temperature of the immediate area surrounding the TRV. You adjust the setting of the TRV to have the overall temperature gradient in the room suitable for yourself. This is done by adjusting the TRV to the air surrounding it.
Now a lot of radiators are mounted under windows, near doors etc as its the coldest bit and then you get airflow, the TRV is used a guide and not an absolute.
So if you install your battery system right next to the TRV it is likely that some of the heat generated by the battery system may affect the temperature that the TRV is reading and so change the heat of the room.
Conversely if you mount the battery system on the most lossy wall (80s timber framed bungalow) at the furthest point from the radiator the battery system heat output might heat the localised area that you had set the TRV higher than it would now be because the heat from the radiator had to pass the distance via all the losses. Now the initial heating doesnt have to be so high because the losses are less and the hot air doesnt have to travel all the way across the room.


Of course if you just read about stuff and dont actually apply, build the system and measure it then how would you know.
If you do build it you walk into the room one night and its almost a degree higher than it was before you installed the system you think,hmm I'll have a look at this..

1961Nick

joefizz wrote: »

Those of you with pylontech might see a benefit after winter of doing a couple of refreshes/resyncs when it starts doing full cycle charging again. Michael from think renewables has put a few videos up on youtube and the install new batteries bit is the refresh/resync.
I do this regularly with my AAs just to mix and match sets of similar power, at some point I might split my batteries from one run of 4 to two runs of two if they start decaying at different rates...

I think I may have witnessed the BMS syncing the batteries.

I'd noticed that the SOC lights were slightly out of sync on one of the batteries - lagging behind on discharge & in front on charge. Everything was working fine but I still planned to balance them after seeing that video on YT.

However, I was in the garage on Tuesday & noticed that 4 of them were charging & one was in standby. Of course I immediately assumed it had failed......but then it goes into discharge with the other 4 still charging. A few minutes later it starts charging & has stayed in sync with the stack ever since.

joefizz

1961Nick wrote: »

I think I may have witnessed the BMS syncing the batteries.

I'd noticed that the SOC lights were slightly out of sync on one of the batteries - lagging behind on discharge & in front on charge. Everything was working fine but I still planned to balance them after seeing that video on YT.

However, I was in the garage on Tuesday & noticed that 4 of them were charging & one was in standby. Of course I immediately assumed it had failed......but then it goes into discharge with the other 4 still charging. A few minutes later it starts charging & has stayed in sync with the stack ever since.

Thats good to know, mine was capping out at about 93% for two days and wasnt going any higher. Maybe if Id left it it would have sorted itself out.. will try that the next time.

1961Nick

joefizz wrote: »

Thats good to know, mine was capping out at about 93% for two days and wasnt going any higher. Maybe if Id left it it would have sorted itself out.. will try that the next time.

Are all your batteries US2000B Plus

I understand that these have a more advanced BMS.

1961Nick

Solarchaser wrote: »

Wow!
I had no idea there was so much data lol, feeling pretty daft

However now Ive found those fields, theres nothing there.
It says 0 under cumulative discharge
Only fields that have numbers are battery voltage, current, soc and generated current.
If I go to history, all the figures in all the fields are the same as total generation.

I'll maybe email the solarman team.

Rather than try & figure out what the issue is, you could try deleting the device & then add the device again by re-scanning the data logger bar code.

joefizz

1961Nick wrote: »

Are all your batteries US2000B Plus

I understand that these have a more advanced BMS.

Yeah they are, part of the reason for adding sooner than expected was to ensure I had batteries with the same firmware.


Still waiting on the first youtube strip down video for them, and no, its not going to be me ;-)

Solarchaser

joefizz wrote: »

Kev, if you are reading the web browser interface for solarman (http://home.solarman.cn) gives a lot more detail, or at least its a lot clearer, well when it doesnt revert to mandarin it does..

Thanks Joefizz and mre15 (cant multiquote for some reason)

It's set to storage, and I logged in through the link, the battery is showing no data.
I dont know why.
If I look in the app history, I can see data for the last week, but as soon as I increase past a week it says it has no data at all.
I've emailed solarman.
I assume the data is there, it's just not displaying for some reason.

Solarchaser

1961Nick wrote: »

Rather than try & figure out what the issue is, you could try deleting the device & then add the device again by re-scanning the data logger bar code.

Tried it thanks.
For a few panicked moments I had no data at all, then it came back, but still no battery data unfortunately.

And to be honest I think it's really the only data that matters when it comes down to it.
Any power used to charge the batteries was surplus anyway, I'm not charging from the grid, only excess solar that I generated but couldn't use.
So in that respect the round trip losses dont really matter... unless you had another use for the power.
If you use 2% or 98% of the power that was otherwise going to the grid, to make a water feature work, then it's a *good* use of the power, as it's better than no use of the power... unless you look at it from the green aspect I suppose.

A hot water cylinder is something I'm toying with, but it would only ever get power once all the batteries were fully charged.

So if I've discharged 100kwh then I've *saved* £14
And then only around £6700 to go till break even :rotfl:

Zarch

The data geek in me would be very interested in seeing the screens/data/stats coming out of the Sofar Inverter and Pylontech batteries. (SolarMan website and app?)

If I ever did take the battery plunge i'd need to know I could get to the underlying stats. :rotfl:

zeupater

joefizz wrote: »

Ok, heres the non silly explanation.
TRVs measure the temperature of the immediate area surrounding the TRV. You adjust the setting of the TRV to have the overall temperature gradient in the room suitable for yourself. This is done by adjusting the TRV to the air surrounding it.
Now a lot of radiators are mounted under windows, near doors etc as its the coldest bit and then you get airflow, the TRV is used a guide and not an absolute.
So if you install your battery system right next to the TRV it is likely that some of the heat generated by the battery system may affect the temperature that the TRV is reading and so change the heat of the room.
Conversely if you mount the battery system on the most lossy wall (80s timber framed bungalow) at the furthest point from the radiator the battery system heat output might heat the localised area that you had set the TRV higher than it would now be because the heat from the radiator had to pass the distance via all the losses. Now the initial heating doesnt have to be so high because the losses are less and the hot air doesnt have to travel all the way across the room.


Of course if you just read about stuff and dont actually apply, build the system and measure it then how would you know.
If you do build it you walk into the room one night and its almost a degree higher than it was before you installed the system you think,hmm I'll have a look at this..

Hi

I, like many others on the forum, fully understand how TRVs work and wouldn't have thought that it would be a particularly good idea to install a modular battery system, especially one with lithium batteries, on the floor close enough to a wet heating system's compression joints for the convected or radiated heat to directly effect the TRV significantly more than the whole room air temperature ... this being especially so when the level of insulation and other measures, far from being those of a typical '80s timber framed bungalow' don't apply as the property has been renovated to 'as close to passivhaus and canadian leed standard as the external construction would allow' ...
... I just don't follow the logic as anyone with significant IT, electrical or electronics exposure would surely avoid the described situation like the plague!

The referenced reason/solution also raises another logical inconsistency ... if the batteries are close enough the TMV for the heat to cause the TMV to close before it should, surely the room would logically be cooler than the set-point & if on the other side of the room the position raised earlier would apply, ie the battery would help raise the thermal mass of that room above a non-heated state, but wouldn't warrant turning the thermostat down - unless the room is abnormally sized ... anyway, on a typical deep winter's day (say mid Nov to early Feb) with generation anywhere near 1kWh/kWp, the round trip energy losses of energy diverted to batteries when converted to heat in a day would equate to around 1/3 to 1/2 that of someone sleeping in the room overnight (say 800Wh vs 300-400Wh (?), so a contribution, but in terms of overall domestic heat loss, not particularly significant even in a building conforming to full passivhaus standards! ... with considerably higher summer generation things may be different, but then again, whatever the TMV setting, the heating wouldn't be on so it's not an issue! ..

Regarding reading & doing ... I don't really understand - as you're aware from the discussion, we use less energy in total per year than yourself, so queries aren't based on relaying information gleaned from others, they're from direct experience ... as for 'how would you know', well that'd be down to looking at the specifications and applying some physics based logic as opposed to the alternative ....

HTH
Z