OFF grid system

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OFF grid system

Postby colint50 » Fri Jun 18, 2021 11:56 pm

Hi, My elderly neighbour (I'm old too!) has some problems with her stand alone solar power system and I would greatly appreciate any guidance to help resolve her issues. Around 18mths ago she had a Giant Power 48v system installed (4K inverter), Panels 8 x 220W (1.3K), 4 x 12v 220Ah batteries in series. The batteries and panels were secondhand at the time apparently.
After about 10mths each of the batteries started to collapse so she had them replaced over a few weeks.
The system indicator shows that the batteries are not being now fully charged (winter of coarse) so I have had to regularly run her generator at the end of each day.
Her usage - has a new fridge, runs a TV/satellite receiver, lights are 12v LED's and her average daily use is just under 2Kwh, lowest watts used around 22W, going up to highest 300w during a 24hr period. Have used a power meter to measure usage.

A couple of days ago when I wasn't around, day was very cloudy and when I went to start the gen at night, it hiccuped, coughed and spluttered and went into overload...generator was ok with no load. She lost power totally last night, and possibly same tonight as generator again went into overload.
I suspect that one of the batteries has failed and the small generator (2K) is struggling.

The problems are twofold - what to do to keep things going temporary now, then what needs to be done in the long term.
Longer term I suspect that more panels are required....any advice on how many? Also to ever increase battery capacity at anytime would be expensive @ 48V....4 banks of batteries each time.
The inverter/charger in the Giant Power setup doesn't tell me how much power is received each day, only tells me what is actual input at any instant of time. The battery symbol shows batteries charged 3/4 only at end of day. The inverter/charger does have a connector to interrogate system but don't have any software to run on laptop. Peak charge is set at 56.4V and generally gets to that level during the day.
The panels are wired as 2 banks of 4 back to the two isolating switches.

I hope I have been able to explain what is happening ok and that the expertise on this forum can advise a possible solution...thanks in advance
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Re: OFF grid system

Postby Revlac » Sat Jun 19, 2021 8:35 am

There should be a setting in the menu on the inverter to lower the AC charge current, this will lower the current and should help the little generator to run.
It should be in the inverter manual, how to set this, software for the inverter would be available, unless I have totally misunderstood the type/brand of inverter.
220Ah batteries should perform a little better than that, more panels would also be helpful.
Panels, you say 2 banks of 4? what is the specs of those panels?
Haven't lodged in for a long time I'm surprised I got in.
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Re: OFF grid system

Postby colint50 » Sat Jun 19, 2021 2:04 pm

Thank you for the response....I have reduced setting for charging and generator now seems to be ok...needed for next few days because of lots of cloud/rain atm. So appreciate the advice.
My neighbour said she lost power again last night around 10.30pm and when I checked batteries this morning, found the following - 12.2V, 9.2, 12.3 and 12.45V. It seems that the "2nd" battery is failing, which is interesting as it is in the same position of where the previous failures first started ie 2nd battery from main +ve terminal.
Under charge at present, battery appears ok, but this will probably fail tonight when charging is stopped overnight

Details on solar panel - German Solar GSP6-220. Rated current 7.38A, rated voltage 29.82V, short cct 7.87A and 36.72V. The words are in German so hopefully above is correct.
Naturally I don't want to run out and purchase another battery, if the same thing is going to happen, unless problem will be solved by adding more panels and perhaps varying their direction to capture more sunlight especially over winter. Plus the lady is no in a position to throw money around without some logical outcome.
Anyone know where I can get the software to try out? Thanks
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Re: OFF grid system

Postby Revlac » Sun Jun 20, 2021 9:49 am

Looks like the 2nd battery might have a bit of sulphate going on, it can happen, the others can charge high and that one gets left behind, and the bulk charge might not be on long enough for it to catch up therefor one ends up in a slow decline, not sure if thats exactly what is happening, but I have seen this before.
If that battery can be changed with a separate battery charger for a longer time you might get some capacity back, if its not already too far gone.

Assuming the inverter is similar to pip 4048MS the mppt charger has a maximum input voltage of 145vdc, if this is the case, then a string of 4 panels is at the top end of that maximum voltage, usually run 3s panels with that voltage rating, might not mater if its working ok at the moment.

As for software, don't get your expectations too high.... you might have a read through some of the stuff on the AEVA https://forums.aeva.asn.au/viewforum.php?f=64 forum I have used the standard software (Watchpower) and tried solar patrol... more of an occasional curiosity to check overnight consumption.
Hope this is of some help.
Cheers Aaron.
Sorry about the late reply, got locked out of here last night , entered the wrong password its says.
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Re: OFF grid system

Postby colint50 » Tue Jun 22, 2021 11:24 am

Thank you so much for your assistance, it is greatly appreciated, don't feel bad about any delays....you have other things to also do, I am just grateful for any help. I am getting a bit overwhelmed with whatever is happening, the batteries all seemed to be ok overnight on Sun with generator run for a few hours, so I was feeling a bit relieved that the battery may still be ok, but last night she lost power again, even after running generator last night. This morning I measured the batteries and they all looked ok...12.5+, however the inverter had cut out, so turned it off, then on, and all came up ok. Maybe they came back up given no load was then connected.

I will go through the manual and check all the settings including bulk charging, although it doesn't appear to have a time adjustment, but will check. The charge normally goes up to 56.4 but can be adjusted up to 58.4, do I keep it at 56.4?

Re panel input, inverter/charger spec says max pv array open cct voltage 145V as you say, is that 29.8 x 4 (4 panels), plus another of the same. is the system being overloaded by too many panels? Generally with full sun atm, the battery indicator shows it is either 3/4 to full at end of day, but then drops down to 3/4 as night progresses, which is natural with load, but I then run generator.
I will change position of the possible faulty battery to see if that helps. Unfortunately its difficult to take any one of the batteries out of circuit, given its a 48v system and only 4 batteries. She has to keep her fridge running, although may try it when she goes out as she won't be opening fridge door for that time.

Will go and swap battery around and check settings and see what happens tonight....fingers crossed. Thanks again
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Re: OFF grid system

Postby colint50 » Wed Jun 23, 2021 9:36 am

Fortunately power held up last night after running generator for a couple of hours due to still cloudy conditions. Batteries were at 49.8v this morning.
Swapped suspect battery around plus check all setting as per the manual....bulk charging 56.4v, float 54v.
Would the inverter/charger have two inputs at 145v max, given there are two cct breakers foe panel input?
Can I just put a meter across each panel and measure volts to check each panel is working ok or measure at cct breaker to see what total volts are coming in when sun is out?
Not sure what else I can do....any advice would be appreciated
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Re: OFF grid system

Postby Revlac » Wed Jun 23, 2021 9:49 pm

I'm not sure the type of battery you have, If they are Flooded Lead Acid, then that bulk charge voltage seems a bit low, you would have to find the recommended voltage for that particular brand and type of battery, even FLA have different settings from a different manufacturer.

I don't use lead acid anymore, but what I have done when one was down a bit and while the charge controller was in bulk mode and other batteries where full and high voltage, is to connect a car head light, or something smaller to the each battery that is high, this would force more charge into the battery that was down a bit, It worked but do not leave it unattended, I had to be with it the whole time to make sure it Didn't get out of hand, as it could do easily.

I haven't seen one with 2 charger inputs (that would be 4 connectors) unless its newer version, a single charger positive and negative input, it could be a circuit breaker on each wire coming in.
Check the voltage anyway and also check the voltage and amperage on the inverter screen, should have wattage there as well, see if it adds up to what you would expect the panels to produce when working, its highly variable but you might make some sense out of it.
If the panel voltage is close to VMP (per panel) then that would suggest that its working.

Also the other day I changed the inverter low voltage cutout to 48v, now the battery capacity indicator show that as half full....but I know better :)


I think coulomb (on the AEVA) would know more about the recommended panel voltage for these units, it has survived so far, it might be ok.

A full charge on a sunny day should be complete by about midday usually earlier if the amount of panels is enough for the battery capacity used.....or thereabouts, if not then more power input might be required.
Every system is different, so I can't say for sure.

I have a PCM 60X SCC that is playing up at the moment, voltage is reading 2v higher (with battery sensor) than battery voltage, so the batteries are not getting full charge....now I have to figure that one out. ;)

Cheers Aaron.
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Re: OFF grid system

Postby colint50 » Fri Jun 25, 2021 9:13 am

Thank you Aaron for the advice on checking the battery specs....I had just set everything to the system default settings, however battery specs says float 13.5 - 13.8, and bulk charge 14.6 - 15v, so I have now set bulk charge at 58.4v and float charge at 54.8v. It would be such a relief if this change solved the ongoing problems. I would assume with a smaller charge that the batteries aren't going to hold their charge.
The batteries have been holding up by using the generator, plus we have had some cloudy days...hopefully over the next few days we get sunny weather and see how everything holds up.

If need be, I may try your process later if I need to even up the batteries but will see how the increased bulk charge goes first.

In one way I am feel not so bad that I am not the only one that is having problems, but then I fully understand the frustration you would be having with your own issues. All the best in resolving them.
Thanks again Aaron.
Cheers, Colin
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Re: OFF grid system

Postby Revlac » Sun Jun 27, 2021 9:12 pm

That voltage sounds much better, I expect that will help improve the capacity after some time.

Had a few cloudy days here as well, solar has been struggling, but full sun today and all is well.
All ways learning this stuff, but satisfying when things work well. :)
Cheers Aaron.
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Re: OFF grid system

Postby APR » Fri Jul 16, 2021 8:51 am

Hi Revlac, from experience… I would get a dynamic battery balancer and fit it to the cells. For my money, it is worthwhile doing on series batteries even when the batteries are new. The dynamic balancer will continually transfer energy from the high voltage battery l to the low voltage battery to try to keep all batteries at the same voltage. Doing so becomes more important as the batteries age and the internal resistance between batteries varies.

One dynamic balancer/equaliser I have had experience with on old batteries is the HA02 balancer…

https://imgur.com/zNhkbDF

https://imgur.com/n5PDdWv

https://imgur.com/8UpbYYs

https://www.aliexpress.com/item/32800465737.html
2 x Goodwe GW5048D-ES Hybrid inverters, 13kW panels, 20kWh LiFePO4
Mk2 PV Router feeding excess solar generation to a 3.6kW 250 ltr HWS
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