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Newbie mistakes on first solar install

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I installed my first system a month ago and was very chuffed with myself.....

I loaded the software, made some tweaks as I read on the forum (which I thought i understood...lol) and let the system run. I soon noticed that the inverter changed back to grid quite often during the day while it was on Solar but thought that was normal....Then reading some posts on the forum I read that the inverter should only change over once or twice during daylight hours,  I was getting 8 to 9 kWh out of the solar / day but my grid usage only came down by 4kWh.

After a month of thinking that this was normal I eventually reset the software to default, followed Chris Hobson,s Axpert guide and some other suggestions I read, and voila....it now runs the full PV kWh with hardly changing over.

I think my battery settings were the guilty party...lol

 

 

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My Second Mistake:

Connecting my grid directly to the inverter through a 63A double pole breaker and then connecting the inverter output into my old Distribution board.

This worked well enough until I realised that the grid power was also limited to the rating of my inverter....so 4kW output was the load limit...which we worked around until my gas geyser blew a hot water pipe in the middle of the night.....So i switched over to my standby electric geyser till i could repair the pipe.....Wow what a wake up call...Immediate 4kW with only the geyser and normal stuff running.

Now thinking that I am an electrician (which I am not) I decided to split the load and purchased a pre-wired external distribution board and commenced to transfer all plugs and lights over to the new board. All was fine transferring the Live wires (because they were marked on old cb's), but lo and behold...when i started with the Neutral wires which are on the Neutral Bar and not marked.....well, I had to trace each damn one and I am sure what should have been a 2 to 3 hour job took me 9 hours and plenty of expletives....

Even though the system is now working well, The moral of my story is to pay a damn electrician to do this work....

 

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4 hours ago, GVC said:

The moral of my story is to pay a damn electrician to do this work....

:lol:.... No then then this forum would not be nearly as interesting. Mind you there are a few electricians I would not let onto the property if there was a solar install.

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6 hours ago, Chris Hobson said:

:lol:.... No then then this forum would not be nearly as interesting. Mind you there are a few electricians I would not let onto the property if there was a solar install.

This is also true, in hindsight I am actually quite chuffed with the finished job.

I am now at least ready for the proposed Eskom load shedding which is set to start on 14 December for 4.5hrs on weekdays and 5hrs on weekends. This may sound not too bad but the times are implemented for maximum disruption i.e. 06:00 to 08:00 and 17:00 to 19:30......and the utility has implied that it can cut the supply permanently until the municipality pays the arrears.....:angry:

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15 hours ago, GVC said:

I had to trace each damn one

Been there. And can you leave the power down for the whole duration? NOOO! Someone comes by every 5 minutes asking how long will it be...

Can't tell you how often I've done work on a live DB (just turn off the breakers in the immediate vicinity where the work is being done). I know it is wrong and believe me I realise the danger of admitting this on a public forum, but then I hired a real electrician to do a proper split (and install all the extra goodies I needed) and get a proper CoC and all that... and you know what... I watched this electrician do exactly the same!

The other day I touched the input pins on my Multiplus, and I think there was a capacitor there with a couple hundred volts DC on it... because it gave me a mighty jolt... so the irony is that I've carefully worked live ciruits without shocking myself, and then I worked supposedly dead circuits and shocked myself...

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On 11/19/2017 at 8:31 AM, GVC said:

I think my battery settings were the guilty party...lol

hi @GVC, what are your battery settings now, i have a similar situation - axpert turns on and off whole day. soc set to 90%, bmv702 not connected yet.

oh yes, forgot. re loadshedding. can you figure out a setting which will - if grid is going off when battery is say at 90soc, ignore the back to grid order and keep sucking the batteries to say 60soc until either grid comes back or the sun takes over. for as my 'logic' tells me, if i order grid to kick in and the soc is at 90 neither one will supply energy as the grid is off ; i.e. its candle time... :huh:

regards

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2 hours ago, gabriel said:

hi @GVC, what are your battery settings now, i have a similar situation - axpert turns on and off whole day. soc set to 90%, bmv702 not connected yet.

oh yes, forgot. re loadshedding. can you figure out a setting which will - if grid is going off when battery is say at 90soc, ignore the back to grid order and keep sucking the batteries to say 60soc until either grid comes back or the sun takes over. for as my 'logic' tells me, if i order grid to kick in and the soc is at 90 neither one will supply energy as the grid is off ; i.e. its candle time... :huh:

regards

I will post my battery settings as soon as I get home this afternoon.

At the moment I only use solar during the day and grid in the evenings so I don't foresee any major issues. The morning loadshedding start wont be a problem as my SOC will still be 100% and I might have to switch back to utility 3hrs before the afternoon loadshedding time to ensure that my SOC is above minimum threshold.

 

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4 hours ago, gabriel said:

for as my 'logic' tells me, if i order grid to kick in and the soc is at 90 neither one will supply energy as the grid is off ; i.e. its candle time

It's a glorified UPS. They added some settings on top so you can force it to prioritise one over the other, but down low it remains a UPS. If the power goes out, the inverter will run the batteries right down to zero unless the grid returns, or you turn it off. In other words...

1. Grid goes off
2. BMV SoC drops below 90%
3. software changes the config on the inverter to prioritise the grid
4. Inverter remains on battery because there is no grid.

The Multi does exactly the same. When the grid goes out, all the carefully crafted limits (SoC and discharge rates) are ignored and it just powers the load until the battery goes under-voltage or the BMS pulls the plug.

:-)

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8 hours ago, gabriel said:

@GVC

what are your battery settings now, i have a similar situation - axpert turns on and off whole day. soc set to 90%, bmv702 not connected yet.

 

 

Here is a picture with my settings.....and like I said earlier my inverter only changes over once or twice a day now.

Capture.jpg

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Thanks Chris,

The "Back to grid voltage" of 46V was one of the recommendations by an Axpert user on another forum....I will change it back to 48V and see if there is any significant change in the inverter switching performance.

The max charging is based on 10% of my 4 x 110Ah batteries....Is this too low?

My Battery type was also set to Flooded, I am not sure which setting it was, but one of them was the cause for my inverter switching constantly during the day.

 

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1 hour ago, GVC said:

The "Back to grid voltage" of 46V was one of the recommendations by an Axpert user on another forum....I will change it back to 48V and see if there is any significant change in the inverter switching performance.

With Back to grid voltage of 48V you system will switch more rather than less.

1 hour ago, GVC said:

The max charging is based on 10% of my 4 x 110Ah batteries....Is this too low?

No if you have 4 x 105 - 120Ah batteries 10A is good.

1 hour ago, GVC said:

My Battery type was also set to Flooded, I am not sure which setting it was, but one of them was the cause for my inverter switching constantly during the day.

No can't be - all that the AGM / Flooded /User setting does is set bulk and float charge. Flooded/AGM has predetermined settings whilst User allows you to set these values.

Based on the fact that you are due for some selective power cuts I would set Program 1 to SOL and Program 16 to CSO. You will use solar during the day and grid at night and charge batteries with solar during the day and grid in the absence of solar. I would not bother with trying to cycle your batteries lightly as they are going to be used often and the priority would to have them at 100% SOC at all times in anticipation of having a power cut. Obviously when the power is off at night then you cannot have 100% SOC but you would want to charge them as soon as the power came on just in case they follow up with a early morning power cut.

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15 hours ago, GVC said:

proposed Eskom load shedding which is set to start on 14 December

hi @GVC, i was looking all over for confirmation of the above but apart from reading about the molefe handout of 30m by eskom for 'avoiding load shedding' could not find anything - any clues?

God bless

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3 hours ago, Chris Hobson said:

The back to grid voltage is a bit low -  46V is roughly 50% DOD.

It's load dependent, which is really what is wrong with voltage-based SoC determination. Under very heavy load (say 20 amps on those 105Ah batteries), you'll see 46V even at 100% SoC. The moment the load drops, the voltage will pick up again. On the other end of the scale, at a very low load (say 1 ampere), a voltage of 46V means the batteries are practically empty.

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6 hours ago, gabriel said:

hi @GVC, i was looking all over for confirmation of the above but apart from reading about the molefe handout of 30m by eskom for 'avoiding load shedding' could not find anything - any clues?

God bless

This letter was posted by our esteemed mayor.

24174722_1999444310071399_726200098797361220_n.jpg

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It occurs to me that even if Eskom didn't pay Molefe millions (that was wrong), it would still not help anything on the other matter of Billions that are owed by certain municipalities (often run by people with similar allegiances).

It's also interesting to note the targeted time periods: That's right in morning/afternoon peak, least effect on business, maximum effect on residential customers. Not sure what one can read into that... perhaps sommer two birds with one stone, do some demand management at the same time?

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Now for my next wake up call......DO not run 12V gadgets off an individual battery on the bank if you do not have a battery balancer or similar.

My inverter was running at about 70° about a month ago and i read that the guys were putting 12v computer fans on the inverters vents to cool it down.

I did the same and they worked wonderfully, but being a smartass DIY guy, I reckoned I did not need a AC to 12V transformer as I had a whole bank of 12v batteries...:D

 

This week we had a few power failures due to thunder storms and my wife was saying that the batteries were not lasting as long as normal so I checked the software and sure enough the SOC and PV were very erratic. The PV production actually dropped by 50% yesterday.

I measured the individual batteries and sure enough the battery that i was running the cooling fans off was only reporting 10.8v and the others were running 13.0v.

I have now recharged that individual battery back to the same as the others and am just hoping that it is not damaged. (And yes i installed a AC to 12v transformer)

I will be installing battery balancers ASAP.

 

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i wonder if, after having installed the battery balancer, you could reconnect the fans to the battery again - i know it's a theoretical question as you now have a power supply, was just wondering if the balancer would be able to sort out a situation like this :unsure:

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I hope one of the tech guys can answer if this is possible.

I still have it in the back of my mind to replace a few AC lights with 12v ones, like in my garage where the batteries are.:D

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2 hours ago, gabriel said:

i wonder if, after having installed the battery balancer, you could reconnect the fans to the battery again

Depends. I believe these HA jobbies everyone likes so much can pass as much as 2 amps, so it should compensate for a fan on one battery. But if you're going to kludge it, then put a fan on each battery :-) If two fans are good, 4 must be better! :-P

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well i was referring to the fans you get in pcs, i've got two sucking warm air out of my axpert dropping the mean temp by 10 degrees.

i see one of these carry the following specs

Voltage: 12VDC Operating

Voltage: 10.8 - 13.2VDC Started Voltage: 7VDC

Rated Current: 0.07±10%A Power Input: 0.84W

FAN Speed: 1300±10%

RPM MAX.Air Flow: 44.71CFM

which indicates i can, as @plonkster suggests, stick more fans on the unit if i run them from the batteries

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