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Author Topic: Hybrid Inverter draining battery below set point SOC  (Read 1607 times)
mre15
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« on: December 19, 2018, 08:33:51 AM »

Hi

I am new to the solar game and only last week had a system fitted. I have a Solis Hybrid Inverter with 4.6 kW of PV panels and a 2.4kWh pylontech battery (small I know but was going to add more in the future)

My battery will gain charge during the day and will be drawn off all fine down to my discharge set point SOC of 20%

My problem however is overnight when the system isn't being used. My battery will continue to be drained by approx 1% per hour, and will if allowed go down all the way to 0 % when the battery bms will turn itself off for protection.

Does anyone have any ideas of where to start looking for the cause, do I have an inverter setting wrong somewhere.

Any help appreciated.

Mark.
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camillitech
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« Reply #1 on: December 19, 2018, 12:14:25 PM »

Hi there and welcome,

No help really but unless your batteries are Lithium I would think 20% SOC is waaay too low. Pylontech webshite seems a little vague on chemistry.

Good luck, Paul
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
mre15
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« Reply #2 on: December 19, 2018, 04:20:32 PM »

Hi

Yes they are Lithium-Ion Phosphate and designed with a 90% DOD (10% SOC) 4500 cycles or 80% for 6000 cycles.

My problem is I think somehow my inverter is slowly draining power at 1% per hour throughout the night, the inverter seems to permanently showing discharging @ 100W

I have tried to email Solis for an answer but haven't had a reply.
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Countrypaul
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« Reply #3 on: December 19, 2018, 04:52:27 PM »

Did you get the sstem suplied and installed by a single company, in which case I would think they should be the first port of call as it may be questioned whether it is fit for purpose if it discharges teh battery when it is not supposed to be doing anything. I take it you have made sure that there is nothing connected that would draw that power over night!
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mre15
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« Reply #4 on: December 20, 2018, 05:43:19 PM »

Got an email today from inverter manufacturer saying that is a known fault and they are hoping to rectify it with a firmware update.

I have already highlighted my issue to my installer.

So what do I do now ?

Hoping to fix with firmware doesn't inspire me with the confidence that it will be corrected, and how long is the eta, I had no timescale quoted when asked.

Do I contact the installer and tell him the supplied item isn't fit for purpose and get them to change it for something that will work out of the box ?
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offthegridandy
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« Reply #5 on: December 20, 2018, 06:15:28 PM »

Hi Mark.  Sorry to hear your story, very bad luck.

In my opinion you will have the right to reject the goods as not fit for purpose.  Your contract is with the supplier and it is to them you must turn.  You can read up on the "Which" web site but here is the gist of the act.

As with the Sale of Goods Act, under the Consumer Rights Act all products must be of satisfactory quality, fit for purpose and as described. 

The rules also include digital content in this definition. So all products - whether physical or digital - must meet the following standards: 

    Satisfactory quality  Goods shouldn't be faulty or damaged when you receive them. You should ask what a reasonable person would consider satisfactory for the goods in question. For example, bargain-bucket products wonít be held to as high standards as luxury goods.
    Fit for purpose  The goods should be fit for the purpose they are supplied for, as well as any specific purpose you made known to the retailer before you agreed to buy the goods.
    As described  The goods supplied must match any description given to you, or any models or samples shown to you at the time of purchase.

https://www.which.co.uk/consumer-rights/regulation/consumer-rights-act

Not too sure how you are using your set up at present but a short term fix would be to pull the fuse or simply switch off the invertor to save the excessive discharge.  If your not happy to do this the supplier should return to site to make a temporary fix (switch).  Can you put a clamp meter on the supply cable to read how much power is being discharged? Always useful to quote figures when complaining.  Keep a log of all letters and conversations.  If it ends up in court and you have contemporaneous records  and notes of conversations it goes a long way to make your case.

Don't get into a shouting match with the supplier but be firm and explain your situation and tell him what you expect him to do and give a time frame,  which must be reasonable.

Good luck.

Andy
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JohnS
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« Reply #6 on: December 20, 2018, 10:58:29 PM »

Perhaps ask the supplier to wire in a time switch so that the inverter is only powered when needed.  Obviously the switch must be able to cope with 4.6 kW.
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andyswan
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« Reply #7 on: December 21, 2018, 09:12:15 PM »

2.4kWh pylontech battery ... drained by approx 1% per hour

Hey Mark!

Truly sorry to hear about your difficulties from the beginning.

1% of 2,4kW is 24W, so it could be just an internal consumption of the inverter itself, I mean its normal consumption. Unfortunately, Solis wouldn't disclose this simple information on their website, or at least I haven't been able to find it at a glance.

So maybe it isn't a fault or misconfiguration at all, but a problem of the manufacturer/seller/installer not revealing all the details.
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BMW i3
Collecting info to go off-grid in Portugal. Supposed rig so far:
Inverter - Voltronic Axpert VM III 5KVA
Battery - Cpzs Cynetic 24 x 2V 930Ah
Panels - 20 of the cheapest I'd manage to find
mre15
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« Reply #8 on: December 22, 2018, 08:04:34 AM »


Thanks for the comments chaps.

I have done a bit more checking over the system and would agree with you that I think this is normal consumption.  From my testing it has became apparent that the inverter will only run when it has PV Generating or the battery switched on. It will not run from the AC Grid supply alone.

I am assuming this is by design and I don't have a faulty model, most other hybrids seem to run the control system from the grid so don't have this issue.

Therefore, after PV has finished generating for the day the inverter is kept awake throughout the night by the battery. Continually running its monitoring systems etc. and therefore continually draining my battery.

My concern with this is it doesn't care about the minimum SOC that I set and will continue to drain the battery to the point that the Battery BMS will shut it down for safety. Solis don't mention anything about standby consumption and where it should get is power from anywhere.

I have placed the issue back into the hands of the installer at present, they have contacted the supplier about this issue. Presently I have the battery switched off and disconnected to prevent damage, with no solar the inverter is now completely dead with online monitoring showing a plant error.

I find it strange how the inverter can be used to charge the battery using grid power by setting timers etc but can't power itself from the grid, this was a major oversight in design.

Mark
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Nickel2
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« Reply #9 on: December 22, 2018, 09:30:39 AM »

I tend to agree with Andyswan there. I run an EpEver 1kW pure sine inverter (24V) that is left on 24/7. The typical drain in it's quiescent state is 10W. The thing does stay at ambient temperature though, due to the size of the ali heat-sinking.
There is a function I can select on the panel that puts the thing into power-save when there is no load; this makes it shut down if the AC load goes below 3W. It then switches on every 10 seconds and checks for load.
I don't know if your system has a similar function, it may be worth having a dekko at the manual.  Tongue
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« Reply #10 on: December 22, 2018, 10:45:16 AM »

The inverter has to get its own power from somewhere, if it comes from the grid you are paying for it so it uses the batteries. Your problem is you are emptying the small battery completely before the nighttime so of course it finishes off the battery by itself. Either set it to charge for an hour around midnight so it does not drain the battery or raise your DOD to 60% so it does not drain the battery or buy another battery so there is enough power to run the inverter. The inverter needs power overnight to stay awake it has to come from somewhere. There is nothing wrong with the inverter.
« Last Edit: December 22, 2018, 10:47:41 AM by rogeriko » Logged

mre15
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« Reply #11 on: December 22, 2018, 02:08:35 PM »

Hi
I understand the inverter has to get power from somewhere, I would have assumed it would do it without potentially damaging the attached battery. Surely any hybrid inverter should heed the set SOC. The maximum allowed setting for this on the inverter is 30%, this is what I have selected.
The inverter knows the battery is at 30% it also knows there is no incoming PV so surely it should then goto sleep or a very low power mode, or off completely until PV comes back to start up voltage.
Instead it will continue to drain a battery into fault. That is not what I call working correctly. That is a design flaw , hopefully fixable with firmware upgrade.
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andyswan
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« Reply #12 on: December 22, 2018, 02:54:13 PM »

it should then goto sleep ... until PV comes back

can't agree more
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BMW i3
Collecting info to go off-grid in Portugal. Supposed rig so far:
Inverter - Voltronic Axpert VM III 5KVA
Battery - Cpzs Cynetic 24 x 2V 930Ah
Panels - 20 of the cheapest I'd manage to find
rogeriko
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« Reply #13 on: January 12, 2019, 05:13:06 PM »

Anything new going on with this inverter?

https://www.cclcomponents.com/attachments/file/download/id/9237/

There are lots of battery settings available.
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mre15
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« Reply #14 on: January 12, 2019, 07:33:08 PM »

Solis have admitted itís a firmware fault and it should float the battery using the built in grid charger. They are currently testing the new firmware. Hopefully I might get chance to test it soon.
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