Off grid fault identification

[dansol84]

Hi All,
Where to start, a bit of background is probably needed. (not an electrician).

I have just moved house and re installed my off grid solar (originally installed by a mate). I turned it on for a test and it all worked fine ran for a day and charged up the battery bank.

I have just recently had an electrician out to tie my inverter into a safety switch and a double power point in my new shed and now I have issues.

I have 4 x 200w panels in series to a charge regulator that can take up to 120v and 60a (overkill), the positive line has a breaker between the panel and the regulator. My battery bank is 12v and has a breaker on the positive line between the battery and the regulator. The inverter is tied directly to the batteries, then to a safety switch and then to a plug.

(I am pretty sure this is how it was originally installed with the exception of the added safety switch and power point).

Now the issue, it has been raining all week so I have not managed to test the setup til now.

My inexperienced findings. (To the best of my memory)

1, Turned on battery bank then the solar, system all worked.
2, Turned on inverter and the regulator started smoking so I turned off the inverter and it stopped.
3, Engaged solar breaker and battery breaker to the regulator.
4, Turned on the inverter and the regulator started smoking again though the breakers were in the off position so only negative was connected???
5, Disconnected the negative and ran just the inverter off the battery bank and it worked no dramas.

What have I done wrong? Is it my wiring, the inverter or the regulator?

I have no dramas bringing in another electrician but don't want to get stuck with the bill if it's something the last electrician has done and can fix.

Any help would be appreciated, I have a basic knowledge of how the system works and always happy to learn more.

cheers,
Dan

[Mike90250]

You may have to learn electricity. I cannot begin to guess what may be wrong with the system

smoke1.jpg

[dansol84]

Thanks Mike.

Yeah I'm boggled, It all seems straight forward till something goes wrong. Good news is I found the receipt and the MPPT regulator is under warranty, now it's just getting a solar electrician in to advise what was the fault regulator/me/electrician before making a fool of myself. I would not have thought turning on an inverter would create a reaction in a regulator.

cheers,
Dan

[inetdog]

Tell us what the Voc of the panels is. I am not sure that putting your four panels in series will result in a voltage that is safely below the 120V limit of your CC.
Do not just look at the Vmp of the panels, and also recognize that the Voc will rise above the nominal limit when the panels are cold.

800 watts of panel at 12 volts into your battery corresponds to 67A, so I would not call your 60A output capability overkill or even safe. Not all MPPT controllers (just the good ones) are designed to limit the current at the output when the panels are producing too much power.
The load of the inverter will drop the battery voltage and therefore increase the current that the CC will try to put out.
If the voltage at the CC terminals is only 10V, for example, the current would be 80A.

[dansol84]

Sorry, 60 was a typo. This is a link to the unit I have.

http://www.jaycar.com.au/Ecotech/Solar-Power/Solar-Charge-Controllers/SunStar-80A-Advanced-MPPT-Solar-Charge-Controller/p/MP3733

I will need to take a look at the panels to confirm.

[dansol84]

The VOC of the panels is 22V, there is a specification tab in the following link to my panels.

http://www.solarenergyproducts.com.au/index.php/200-watt-12-volt-solar-panel.php

I currently have them in series as it was convenient and seemed to me within spec (if you can confirm). I have the necessary kit to change it to Parallel if its required, though this system has been running in this config for over a year no issue, so I don't think this is the reason for the issue?

[inetdog]

Sorry, 60 was a typo. This is a link to the unit I have.

http://www.jaycar.com.au/Ecotech/Solar-Power/Solar-Charge-Controllers/SunStar-80A-Advanced-MPPT-Solar-Charge-Controller/p/MP3733

I will need to take a look at the panels to confirm.

Looking at the manual at the Rich Electric site (http://www.richelectric.com.au/files...ual_v10809.pdf) shows what appears to be a versatile CC with a lot of features and user-settable options. But nowhere at that site or on any of the dealer sites do I see any indication that the unit is UL listed or even self-certified to any European standard. That makes me very cautious, and if it does not indeed have UL or equivalent (NRTL) sticker it would be rejected by many inspectors and would allow insurance companies to deny coverage after the fact if something happens.

It looks like the maximum input voltage (as opposed to the highest MPPT working voltage) is 140V, not 120V, so you may not have a problem there.

But to find out what exactly is happening I would advise you to get a multimeter which has a DC reading clamp on ammeter feature. You can get one from Sears for about $50. (But note that that have another model for which the ammeter is AC only.)

[dansol84]

Thanks for the link, so all appears to be within spec, and my wiring is correct as per the link also. I wonder if the electrician got water in one of the units, they installed wall sockets in my shed during a day of rain. Left mud and water all over the place.. and it was the first time I had turned the unit on since that this occurred.

I will talk to the supplier about standards, thanks for the heads up on that one.

[LETitROLL]

2, Turned on inverter and the regulator started smoking so I turned off the inverter and it stopped.
Dan

Of course this is your biggest clue, what size is the inverter?, and what size and wiring configuration is your battery bank? Because the batt(s) are probably not new anymore any issue there (bad cell, reduced performance due to age, etc.), coupled with too large of an inverter would for sure cause a significant voltage drop and a possible current surge through the Charge Controller?, most clues after the first smoke don't matter, hard to put the genie back in the bottle.

[dansol84]

Of course this is your biggest clue, what size is the inverter?, and what size and wiring configuration is your battery bank?

The inverter is 12v/240v 1500/3000W but it wasn't actually drawing when the issue occurred, simply turned on, 4 x 130ah 12v batteries in parallel?

most clues after the first smoke don't matter, hard to put the genie back in the bottle.

Good way to put it, I just want to make sure after repair/replace the new genie stays in the bottle. I am arranging a sparkie to come in and take a look, hopefully I can learn something as they go over everything.

[thastinger]

Are you calling the charge controller the "regulator"?

[LETitROLL]

4 x 130ah 12v batteries in parallel?

I have noticed Most of the more experienced system designers on this forum seem to strongly avoid parallel battery banks? (read very strongly).

[dansol84]

Are you calling the charge controller the "regulator"?

Yes, charge controller/charge regulator sorry.

I have noticed Most of the more experienced system designers on this forum seem to strongly avoid parallel battery banks? (read very strongly).

Good to know, I will have a read. I am looking into getting a new inverter anyway, so I should put some research in and if it's as you say I can always go for a 48v inverter.