jonescg's home battery storage system

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Re: jonescg's home battery storage system

Post by mark_hetho »

Forget light-years, Moke-minutes is my new favourite unit of distance. :D
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Re: jonescg's home battery storage system

Post by jonescg »

mark_hetho wrote: Tue, 15 Sep 2020, 08:19 Forget light-years, Moke-minutes is my new favourite unit of distance. :D
Where each stressful minute is longer than the last!
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Re: jonescg's home battery storage system

Post by jonescg »

Had a chat with Brendan about the install and what happened with the EZ Meter. Seems it produced smoke and popped before he gave up, suggesting either it was incorrectly wired or it was faulty to begin with. Either way, it's doing nothing so I need to replace it with a new one and hope it gets wired in OK too.

$300 I'd rather not have to spend, but anywho.
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Re: jonescg's home battery storage system

Post by jonescg »

The new EZ-Meter is installed and the system is working!
No idea why the old one blew up - it was wired correctly, so it must have been an internal failure. Either way I'll be sending it back to Goodwe for a post mortem and hopefully a refund.

But first - the exciting stuff! Richard kindly came around and helped set up the PV Master App for settings and the like, as well as set up the router connection so I can obsess over the data from anywhere in the world. Friday was a magnificent day for solar - blue sky from sunrise to sunset. The battery which was lightly used the night before was full by 10 am. Now, it has no CAN-bus BMS so it's running on a User-defined profile and it's flakey to say the least. It's Coulomb counting somehow to determine SOC, but badly... Still, the 7.9 kW of PV on the roof was doing it's thing:
Sunny Friday.JPG
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Saturday's cold front couldn't have been worse:
Rainy Saturday.JPG
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The cool weather and parting clouds resulted in spiked of 7.2 kW of PV which caused it to drop out, registering it as a load and basically messing with the inverter. Not good - so I climbed up on the roof and bypassed two panels on each array. This means lower power overall, but less likely to trip the inverter on wild days like this one. Today was much the same, but a bit sunnier overall, and the PV never tripped out, so I've concluded that just because I got 28 panels at auction doesn't mean I need to use all of them. Perhaps not an issue for hot cloudless days, but these spring days are chaos for PV. At least the export limitation of 3 kW is working exactly as it should.
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SOC is bollocks - so just ignore it. I'm surprised it doesn't have a low voltage limit on user defined, but then again it's fully expecting BMS data. One day I'll fix that... Synergy has been advised, so hopefully an inspection is imminent and we can sign up for some legit solar!
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Re: jonescg's home battery storage system

Post by francisco.shi »

I noticed you have the same problem as me. When the load suddently drops or the panels suddently put out more power it starts selling power.
Some times it sell power out of the battery at night.
I found that if I set the maximum export limit to 50w it considerable reduces this problem but then I have to keep an eye on the battery charge and set it back to 5kw otherwise it won't sell the surplus.
I talked to the goodwe tech and he kept trying to tell me it is the battery. Then I showed him that if I changed the export limit it would not sell power out of the battery. He then said he would ask the factory.
Maybe you should call him and tell him about the problem. If enough of us complain hopefully they will fix the problem.
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Re: jonescg's home battery storage system

Post by jonescg »

I am not too worried about exporting a hundred watts for four hours a night. Or even consuming a hundred watts from the grid when the household loads are below 100 watts.
The SOC is off the cart because it drops as the battery charges...
I also need to fix the HWS. It ran from midnight to 5 am despite the timer being set for daylight hours.
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Re: jonescg's home battery storage system

Post by francisco.shi »

It is not hundreds of wh. I have had 2.5kwh exported on a day when the battery never charged to full because it was cloudy. The worse I have had was 15% of the total harvest sold to the grid even when the battery kept charging all day.
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Re: jonescg's home battery storage system

Post by jonescg »

I should point out the spike at 10:15 am on Friday was when I set the export limit to 4.9 kW for shits and giggles. The change saw it export >4 kW, but also somehow perceived it as a load.
So it must use a power destination (load, charge, or export) as a surge tank when diverting, even if only briefly.
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Re: jonescg's home battery storage system

Post by francisco.shi »

The reaction time from the control loop for the battery current is very (exceptionally) slow. So if you have a load that suddently turns off it keeps pumping power out of the battery. Also if the solar is charging and a load suddently turns on it keeps pumping power into the battery and then it buys power.
My inverter it seems to be getting worse. I am not sure if it is learning something from the battery.
I on average I end up selling 2.5kwh and also buying 2.5kwh just from that lag.
However if the mains goes out it runs off the battery instantly and there is no interruption of power.
So my guess is that it is done in purpose but not very sure why. In my view is is very bad for the mains because it is pushing a lot of spikes in and out of the mains so not sure it has to do with compliance of some sort.
As for the SOC it totally does not make any sense. It appears to be a function of the current going into the battery. When current comes out SOC goes up.
I have the feeling that it may be trying to compensate for internal resistance if the battery and if we put a Lithium battery with significantly lower internal impedance it may get the compensation wrong.
I have tried to change the Ah setting but it does not appear to have an effect. I am not even sure what the Ah setting is meant to do.
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Re: jonescg's home battery storage system

Post by jonescg »

I just realised the main stickers I'm missing are the green ES sticker, and the UN3480 sticker (I think). Everything else is sorted I believe. Anyone have a few spare?
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Re: jonescg's home battery storage system

Post by brendon_m »

jonescg wrote: Mon, 21 Sep 2020, 08:00 I also need to fix the HWS. It ran from midnight to 5 am despite the timer being set for daylight hours.
Mine did this every Wednesday night (Thursday morning), it was an anti bacterial function that has to bring the water temperature over 60°C at least every 7 days. Strangely if I cranked the temp to over 60 on one random day it didn't start the 7 day count from there but still ran on Wednesday nights. I've now cranked the temp to over 65°C and left it there and I haven't noticed it happen since.
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Re: jonescg's home battery storage system

Post by jonescg »

brendon_m wrote: Mon, 21 Sep 2020, 13:19
jonescg wrote: Mon, 21 Sep 2020, 08:00 I also need to fix the HWS. It ran from midnight to 5 am despite the timer being set for daylight hours.
Mine did this every Wednesday night (Thursday morning), it was an anti bacterial function that has to bring the water temperature over 60°C at least every 7 days. Strangely if I cranked the temp to over 60 on one random day it didn't start the 7 day count from there but still ran on Wednesday nights. I've now cranked the temp to over 65°C and left it there and I haven't noticed it happen since.
OK found out what had happened. A power outage must have happened which caused the timer to reset. So of course the ON time was 12:00...
Fixed and sorted.
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Re: jonescg's home battery storage system

Post by jonescg »

I called Synergy and asked about the DEBS scheme, and they said I'm ineligible because my system exceeds 5 kW. Now, that might be true in terms of PV but the inverter can't make use of more than 6.6 kW anyway. So I have applied for a 'change of hardware' through Western power where everything stays the same, but my PV is reduced to 24 panels at 275 W each.

Hopefully that means I'm allowed to get paid 3 cents for what I export - which would help pay for the little bit that gets consumed at night when there's so little running.

Speaking of - Brendon, do you have your fridge connected to the back-up circuit? I'm wondering what your night time draw from the grid is. It looks like so long as there's a load of 100 W, it won't draw from the grid, but I'm curious if that makes a difference on the back-up line.
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Re: jonescg's home battery storage system

Post by brendon_m »

I have an upright fridge and an upright freezer on the backup. As a general rule the meter floats around 10W in from the grid over night and my standby draw is 175W to 400W. It doesn't differentiate between the grid side and backup side on the graph
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Re: jonescg's home battery storage system

Post by brendon_m »

Screenshot_2020-09-29-18-18-44-467_com.goodwe.semsportal.png
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Re: jonescg's home battery storage system

Post by brendon_m »

jonescg wrote: Tue, 29 Sep 2020, 14:21 Now, that might be true in terms of PV but the inverter can't make use of more than 6.6 kW anyway.
Dunno, I've noticed my inverter sucking up the solar beyond 6.6kW
Screenshot_2020-09-29-19-42-22-656_com.goodwe.semsportal.png
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Re: jonescg's home battery storage system

Post by jonescg »

I saw 8 kW at one point - from just 6.6 kW worth of PV! These Canadian Solar modules must really like the cold...

It certainly does make use of all the PV - At one point I had 6 kW or so coming in, and 4.9 kW was going to the battery, 1.1 kW to run a few loads and a handful of watts out to the grid.

When I had all 28 panels hooked up it was exceeding 8 kW regularly when the clouds would part and a blast of direct sunshine would linger for 4 or 5 minutes. The PV would drop to 0 V and take about 5 min to slowly come back on line. During this period the data analyser logged a huge spike in household load, which is consistent with a rapid shut-down of PV which ordinarily supports loads ahead of battery charging.

So in effect I've gone back to a standard system. Meaning, if I'm entitled to a few cents for the exports, I might as well.
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Re: jonescg's home battery storage system

Post by antiscab »

The wording is around inverter capacity, ie. Your inverter needs to be 5kw or less 😯

Edit: For some reason I thought you had a 10kw inverter, not a 5kw one. In which case, that means synergy has (recently?) taken a very different definition of the 5kw limit. It used to be 5kw inverter limit, and as much solar as you like (the 6.6kw limit was about getting the RECs)
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Re: jonescg's home battery storage system

Post by francisco.shi »

At 3c/kwh it is not worth having panels unless you use up all the energy.
Without a battery I would only use 30% of the generation and had to buy back the other 70% later.
How much is a kWh to buy?
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Re: jonescg's home battery storage system

Post by brendon_m »

antiscab wrote: Tue, 29 Sep 2020, 21:33 The wording is around inverter capacity, ie. Your inverter needs to be 5kw or less 😯

Edit: For some reason I thought you had a 10kw inverter, not a 5kw one. In which case, that means synergy has (recently?) taken a very different definition of the 5kw limit. It used to be 5kw inverter limit, and as much solar as you like (the 6.6kw limit was about getting the RECs)

I looked a few weeks ago and it was still 5kw and related to the inverter. My guess is someone along the line wrote the wrong figure or misheard or most likely, misunderstood.
@jonescg "I have a 5kW inverter and 6.6kW of panels"
Random non technical pen pusher "oh, it says here the limit is 5kW. DENIED!"
@jonescg "but, it's only a 5kW inverter"
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Re: jonescg's home battery storage system

Post by jonescg »

francisco.shi wrote: Thu, 01 Oct 2020, 05:46 At 3c/kwh it is not worth having panels unless you use up all the energy.
Without a battery I would only use 30% of the generation and had to buy back the other 70% later.
How much is a kWh to buy?
28c a unit on A1, anywhere from 21c to 50c if you're on the variable rates.

It's more about offsetting the daily connection fee, and eventually, being able to play arbitrage with the grid.
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Re: jonescg's home battery storage system

Post by francisco.shi »

I was thinking about that too but at 3c/kwh If your daily charge is $1 you would need to sell 33kwh just to cover the cost of having the wire to your house.
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Re: jonescg's home battery storage system

Post by jonescg »

francisco.shi wrote: Thu, 01 Oct 2020, 10:46 I was thinking about that too but at 3c/kwh If your daily charge is $1 you would need to sell 33kwh just to cover the cost of having the wire to your house.
In summer that's entirely doable. Rather pay ~$200 a year to be connected than $365 a year.
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Re: jonescg's home battery storage system

Post by brendon_m »

My 7¢ isn't looking so bad now...

:( I miss my old 47¢ FIT
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Re: jonescg's home battery storage system

Post by francisco.shi »

The question is:
Is it worth to pay $200 per year to be connected to the grid if you can generate all the energy you need.
A 5kw inverter is obviously not big enough but if you had a say 10kw inverter and you could use your car battery as backup as well as your home battery you could potentially run completely off grid. In the case of a few rainy days you could go to the fast charger and bring some electricity back home.
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