Good evening wise solar people of the web.

I have recently had a solar system installed on my house, and I feel some errors have been made but my installer totally disagrees with me.

So I am in JHB and had a system installed by a Cape Town based company which is probably my first and biggest mistake. The second mistake is the equipment installed seems to be pretty much exclusively imported by the Cape Town company and as a result no one else wants to, or knows how to work on it.

So the reason I went with this company is that I really liked the system that they supplied and the price was fantastic. I would really appreciate some constructive criticism/advice for those in the know if I may please.

So let me get right into what I have and then I'll list my concerns.

I have 24 x 455 Watt Mono Panels

2 x 5kw SRNE Inverters 

3 x 5.12kw Pytes batteries 

I am running my house and the cottage on the property from the system. In winter the property uses 55kwh/day and in summer around 35kwh/d

At present the system is generating 30-35kwh/day on a zero cloud clear sky day. I am currently using about 23kwh/day of mains supply. The batteries are going through to about 2:00am and then recharge. That charge then gets us to sun up with about 60% capacity left.

The geyser in my house is a PV element conversion from Geyserwise. The cottage geyser is the standard 3kw kwikhot on a timer from 9:00 - 10:30 and 14:00 - 14:45.

With an installed capacity of almost 11kw of panels (obviously I won't get that full amount, but I would hope for at least 75%) I am only seeing an absolute best ever peak of 6.2kw and that is for a maximum of about an hour, then I tapers off sharply again.

12 of the panels are directly North facing at 30° and the other 12 are flat on the east slope which has about a 20°slope facing East.

Realistically in JHB at this time of year, is 30-35kw within spec or could I get better?

We often temporarily get a draw of 8kw/h which is hammering the batteries. Most days the batteries are not fully charged by 16:00 when the panels are pretty much done for the day.

The supply wires coming from each bank of 12 panels are 6mm2 but get pretty hot at mid-day.

I am concerned that these Wires are too thin and could be seriously restricting power if they are that temperature supplying+-3kw each approximately.....and what is going to happen in summer when the sun is really pushing? Are these Wires able to carry the supply from 12 x 455 watt panels.

Would properly angling the 12 panels on the East Slope to face North make a notable difference or am I wasting my time?

This system is probably more than perfect for 99% of the houses out there, but in my case I'm needing to get as much performance as possible to make it really work.

I'm not opposed to re-mounting the panels or running second wires from each bank, but don't want to spend unnecessarily. 

Another concern I have is that there are no battery disconnect switches anywhere on the system. I was told it's not necessary because the batteries all have power switches on, but would just like to make sure that is the case?

On other possible issue I have is that one of the DC breakes in the combiner box has tripped twice now, and it's rated at 500v and 6000A. There is also a bridge between the two incoming supply lines, so how does only one trip?

The inverters show inputs of around 50-70V and 40-70A each, this obviously constantly fluctuates.

Apologies for all the questions. I have just been spinning my wheels endlessly searching for answers on Google and was thrilled to find this community.

Edited July 2, 20224 yr by LCG

My combiner box.

My system 

Your stats could be in line with what one could expect not knowing what time of day power is used. Your 6.2kw peak seems to be low but only if you are sure you have more than that connected.

The fact that you use grid to charge during the night and still have 60% you can cut the grid use by lowering the inverter setting not to charge them full but to a point where there is about 25% left when the PV kicks in.

Further you panels at 20 degrees will not produce much power during winter. Also facing them north would yield more over the course of a day. The re-positioning is free power.

Although one can see the combiner box it is not clear how many string and series connections you have and the orientation of these.

Just something on the DC MCB the figures you quote are maximum before they rupture and not of much value to work out why it tripped. This is dependent on the various strings of the 24 panels.

Edited July 3, 20224 yr by Scorp007

4 hours ago, Scorp007 said:

Your stats could be in line with what one could expect not knowing what time of day power is used. Your 6.2kw peak seems to be low but only if you are sure you have more than that connected.

The fact that you use grid to charge during the night and still have 60% you can cut the grid use by lowering the inverter setting not to charge them full but to a point where there is about 25% left when the PV kicks in.

Further you panels at 20 degrees will not produce much power during winter. Also facing them north would yield more over the course of a day. The re-positioning is free power.

Although one can see the combiner box it is not clear how many string and series connections you have and the orientation of these.

Just something on the DC MCB the figures you quote are maximum before they rupture and not of much value to work out why it tripped. This is dependent on the various strings of the 24 panels.

Thank you for the input.

Would single 6mm2 wires be sufficient for 12 x 455watt panels?

I'm concerned that re-angling those panels will either create too much power for the wires to handle, or would restrict any additional power form being able to make it through due to a large voltage drop?

All I know currently is that there are two inputs from solar, one input for each 12 panels,  and they are bridged at the Breakers. I will have to have a look how the strings were connected when I remount the 12 panels on the East slope. That is really the only way to see enough of the wiring to figure out what's up.

 

Edited July 3, 20224 yr by LCG

1 hour ago, LCG said:

Thank you for the input.

Would single 6mm2 wires be sufficient for 12 x 455watt panels?

I'm concerned that re-angling those panels will either create too much power for the wires to handle, or would restrict any additional power form being able to make it through due to a large voltage drop?

All I know currently is that there are two inputs from solar, one input for each 12 panels,  and they are bridged at the Breakers. I will have to have a look how the strings were connected when I remount the 12 panels on the East slope. That is really the only way to see enough of the wiring to figure out what's up.

 

Sorry I missed the voltage at each inverter and the current. Each 12 panels is thus wired 2 S x 6 P. If the power for each 12 at 70A is far too high for single 6mm wire. I take it the closed  box is to the right of the inverters? If so then at least 2x6sq mm wire per polarity should be wired to each inverter. That is what I would do.

Edited July 3, 20224 yr by Scorp007

16 hours ago, LCG said:

My combiner box.

Are those 125A fuses on 6mm² wires? 3 of those breakers look like AC breakers?

1 minute ago, P1000 said:

Are those 125A fuses on 6mm² wires? 3 of those breakers look like AC breakers?

The installed must have worked on the 20A fuse to be used on a panel. Thus with 6P strings he got to 125A. Way too high.

1 hour ago, P1000 said:

Are those 125A fuses on 6mm² wires? 3 of those breakers look like AC breakers?

The two on the right are DC and the others are AC, it's a bypass switch to go back to direct council supply if needed.

 

Yes, there is 1 x 125A fuse per 6mm2 wire.

Edited July 3, 20224 yr by LCG

1 hour ago, Scorp007 said:

Sorry I missed the voltage at each inverter and the current. Each 12 panels is thus wired 2 S x 6 P. If the power for each 12 at 70A is far too high for single 6mm wire. I take it the closed  box is to the right of the inverters? If so then at least 2x6sq mm wire per polarity should be wired to each inverter. That is what I would do.

Thanks. I'm now quite concerned about potential safety issues heading towards summer with those wires and a 125A fuses on each.

By early afternoon that combiner box tends to get pretty hot inside and smells of burning electronics. 

There is a single 6mm2 wire per polarity to each inverter. Those wire get just as hot as ones coming in from the 24 panels

 

Edited July 3, 20224 yr by LCG

I think those inverters are low voltage machines, working with a voltage range of 60V to 145V MAX on the DC side. I suggest you get a local installer to have a look and repair the install before something catches fire. 6mm2 wired through a 125A fuse is a no go.

26 minutes ago, TimCam said:

I think those inverters are low voltage machines, working with a voltage range of 60V to 145V MAX on the DC side. I suggest you get a local installer to have a look and repair the install before something catches fire. 6mm2 wired through a 125A fuse is a no go.

Thanks. I will certainly do that. 

People: Any suggestions on someone I could contact in the Johannesburg (Sydenham/Orange Grove) region who would be able to sort this out, and take over supporting the system for me going forward?

15 hours ago, LCG said:

The two on the right are DC and the others are AC, it's a bypass switch to go back to direct council supply if needed.

 

Yes, there is 1 x 125A fuse per 6mm2 wire.

I don't think you can mix AC and DC in a box like that - much less the conductors overlapping like that.

6mm² wire will act as a fuse long before the 125A fuse.

15 hours ago, LCG said:

By early afternoon that combiner box tends to get pretty hot inside and smells of burning electronics. 

Hot temperatures will cause oxidation on contacts, which will increase resistance and cause even more heat. This will burn down. Get a qualified electrician to fix this install asap and that can issue a COC. I am shocked to see that someone would install battery fuses of 125A on 6mm wire

39 minutes ago, iiznh said:

Hot temperatures will cause oxidation on contacts, which will increase resistance and cause even more heat. This will burn down. Get a qualified electrician to fix this install asap and that can issue a COC. I am shocked to see that someone would install battery fuses of 125A on 6mm wire

......and they gave me a COC for this installation. 

They also used ferrules wrapped in insulation tape to connect up the panels, rather than the correct connectors. When I questioned that they told me it s far more reliable method than the connectors which leak and fail?

 

Edited July 4, 20224 yr by LCG

At present I have been unable to find anyone who will even come and have a look at my install and correct the issues. No one wants to get involved in someone else's work 😒

I'm getting concerned about how hot things are getting so I am going to address the immediate issues myself this weekend.

I am going to run second 6mm2 wires from each bank of panels and I'm upgrading the 63A Breakers to 100A.

With double 6mm2 wires which have combined capacities of 140A, the 125A fuses and 100A Breakers give a good safety margin and the panels will never give more than the wires carry.

As mentioned before, I have seen the inverters each reading around 70V and 70A. I just looked at the inverters now and I see they are each rated at a max of 4400w and 50A. My panels are essentially 5460w per inverter. Is this an issue or can the inverters manage the additional power?

 

 

Edited July 8, 20224 yr by LCG

10 minutes ago, LCG said:

So I have so far been unable to find anyone who will even come and have a look at my install and correct the issues.

I'm getting concerned about how hot things are getting so I am going to address the immediate issues myself this weekend.

I am going to run second 6mm2 wires from each bank of panels and I'm upgrading the 63A Breakers to 100A.

With double 6mm2 wires which have combined capacities of 140A, the 125A fuses and 100A Breakers give a good safety margin and the panels will never give more than the wires carry.

As mentioned before, I have seen the inverters each reading around 70V and 70A. I just looked at the inverters now and I see they are each rated at a max of 4400w and 50A. My panels are essentially 5460w. Is this an issue or can the inverters manage the additional power?

 

 

Normally your panels would only provide 4400W but even that is 10% over the max of 4000W. Also it might clip it to 4000W but stressing some components and generate heat. On this type of inverter I would prefer not to do.

Perhaps wire panels in 2S x 5 strings each.

3 hours ago, Scorp007 said:

Normally your panels would only provide 4400W but even that is 10% over the max of 4000W. Also it might clip it to 4000W but stressing some components and generate heat. On this type of inverter I would prefer not to do.

Perhaps wire panels in 2S x 5 strings each.

I have two banks of 12 panels. Would the above configuration of 2 in series and 6 in parallel still work or would it still overload? I have CSUN455-144M panels.

The installers put bridges between between the two Breakers, so I assume it would balance the input between the two inverters with the one bank being East facing and the other bank North facing? So essentially both banks would not reach peak output at the same time?

Edited July 8, 20224 yr by LCG

14 hours ago, LCG said:

As mentioned before, I have seen the inverters each reading around 70V and 70A.

I'd guess that this is from the front panel or from monitoring software. People don't realise that Axperts (this is an Axpert near-clone) quote the PV current at the battery-side of the solar charge controller. So this is not 70 V x 70 A = 4900 W, this is probably more like 53 V x 70 A = 3710 W.

Quote

I just looked at the inverters now and I see they are each rated at a max of 4400w and 50A.

It's unusual for an Axpert or Axpert near-clone to quote a maximum PV input current. 3710 W / 70 V = 53 A, not far over the limit. A genuine Axpert doesn't even measure the input current, only the output current, which is what the SCC's transistor sees anyway. So I would not worry about the 50 A figure.

Quote

My panels are essentially 5460w per inverter. Is this an issue or can the inverters manage the additional power?

If the control algorithm of the solar charge converter was perfect, it would not matter at all. The SCC would just use what it needed, and the rest would be wasted as heat in the panels. But of course, the control algorithm is far from perfect, so there will be overshoots and undershoots. The overshoots (of both MPPT current and battery voltage) are the problem. The former causes the SCC to get hotter, and the latter either damages the battery, or causes the BMS of the battery to disconnect from the inverter, with possibly bad consequences.

My rule of thumb is to not exceed the rated power by a factor more than 1.2 - 1.25x. Rated power here seems to be 4200 W (52.5 V x 80 A), so the limits would be 5040 - 5250 W. So you are more like 1.3x, but some of the panels are east facing and others north facing, so you'll never get full power from the array if each inverter gets a mix of each. My guess is that you'll just be OK.

Since you have seen 70 V from the panels, that settles the 2S versus 3S argument: these must be 2S. With large panels like that and the 145 V absolute maximum PV voltage, 2S is the best configuration.

On 2022/07/02 at 11:01 PM, LCG said:

Realistically in JHB at this time of year, is 30-35kw within spec or could I get better

I have 6 panels facing N and 6 facing E. Lower output than yours. I could get 15 to 16 kw/h on a sunny winter day. So I think that expectation is realistic.

The 20 deg slope for the E facing is a bit shallow for this time of year, but unless you are going to get adjustable mountings, the reality is that your panels will only be correctly aligned twice a year. The flatter angle will do better for you in the summer.
 

On 2022/07/02 at 11:01 PM, LCG said:

With an installed capacity of almost 11kw of panels (obviously I won't get that full amount, but I would hope for at least 75%) I am only seeing an absolute best ever peak of 6.2kw and that is for a maximum of about an hour, then I tapers off sharply again.

Looking at my data for yesterday, I got a maximum of 3.7. So, again, I think you're in the ballpark here (I am in Randburg). It would depend on the exact orientation of the panels and their output. I have 1/2 the panels, lower output, but a steeper angle (about 35 degrees).

You mention realigning your E facing panels to face N. Are they truly facing E (my two arrays are at 90 deg to each other), or do they face something E of N? I doubt you can swing your roof through 90 deg 🙂 

 

On 2022/07/02 at 11:01 PM, LCG said:

We often temporarily get a draw of 8kw/h which is hammering the batteries. Most days the batteries are not fully charged by 16:00 when the panels are pretty much done for the day.

Can you reduce loads in your house? Do you have underfloor heating? Electric oven & hob? The 15 to 16Kw/h I get in winter will recharge my batteries from about 50% and keep the house going. This includes heat pump (not geyser element) & pool pump.

So can you turn down the temperature on the geysers? If you're heating the water so hot that you have to add cold water then you're overheating for nothing. I'd suggest trying to shuffle loads around into the sunlit hours, but when your consumption exceeds production by 20kw/h then that seems unlikely to help. Reducing the loads will help.

And do you have a manual for those inverters? With mine (Goodwe) I can set up rules to say "charge the batteries from grid (if available) at this current, at this time of day". So, like you, I like a full battery around 16:00, so I have a rule to charge the battery from 15:30 to 16:00. In my case it's unusual to have the batteries so discharged by 15:30 that I can't top nearly all the way up in that half hour.

Also see if you can limit the draw from the batteries. Mine is setup so that when we have grid, it stops drawing from batteries when SOC gets down to 40%. If there is no grid they will take the batteries down to 90% (at which point the batteries will turn off anyway). So I always have 3 Kw/H on hand in case of an outage. For the essential circuits. The system doesn't back up the whole property, so I lose some circuits (EG pool pump) when the grid goes down.

Just to return to the comparison of the performance of our two systems (you can see mine described in my signature), I usually hit 45 to 50% SOC around 7:30 in the morning. With less battery than you. From 16:00 on we very seldom draw more than a kilowatt (maybe a quick burst of microwaving) and the draw averages out at about 40O W continually. We have full gas for cooking, and a rule that we only use the old-fashioned, whistling type kettle, on the hob, from 16:00 to 8:00. We don't run the water heating at night (it's still plenty warm enough at 19:00). We don't run electric heaters. Maybe try to figure out what's using electricity when and see what you can cut back on. Try to get whoever lives in your cottage on-side, as well as your family.

The inconvenient truth is that to maximise any alternate energy system, we have to modify our own behaviour - or spend very large amounts of money on a very large system.

I haven't answered any of your technical questions. Folks that are better equipped than I am have already given you answers to those. I'm merely offering you insights into how my system (which is about 1/2 of yours) is operating.

Edited July 9, 20224 yr by Bobster.
grammar

Thanks for all of the input folks, it's greatly appreciated. I am just about done running the second wires for each bank and will probably connect up when the sun dips this afternoon.

So working on this wiring has given me a little more of an understanding of how everything is set up and was a good exercise to undertake.

There is an approximate 10V drop from panels to the inverters. Not sure if that is a big issue but I assume on a lower voltage system like mine it's probably a decent amount of loss . I assume the lower voltage is possibly causing the amps to climb under load and that is what is causing the one 63A Breaker to trip.

Even if performance doesn't improve from my efforts I'll be happy that it's a safer setup, and I won't have to deal with the one breaker tripping all of the time.

As far as the consumption goes, I have just installed a 5.4kw heat pump (1.2kw draw) and a second 150lt geyser, so I can program that to run between the other big loads and won't run out of hot water.

My big issue remains the geyser in the cottage which only runs during the day but its a 3kw element. Now if my wife switches on the dishwasher and washing machine at the same time thats another 4kw, plus the 3kw geyser, plus the normal house draw and we are at 8.

I am planning to put a 2kw element in the cottage geyser and run it for longer, then run hot water supplies with tempering valves to the washing appliances. That won't stop them drawing but will certainly shorten the amount of time that each 2kw element is running for.

My mom in law lives in the house with us and there are two adults in the cottage, so we are total of seven people with the kids.

I'm asking a lot from this system, but so far my mains consumption is down from 55 units a day to 23, so its clearly working. 

And it is done! I am shit scared of heights so crawling around on the roof all day is enormously taxing and I'm stuffed.

So while there is probably a compliance issue with AC and DC being in the same combiner box, I don't believe it presents any immediate safety issue. I will address that with the installers next time they are in Jhb and plot a way forward on that front.

So it was a tight squeeze but I now have 2 x 6mm2 wires per polarity, per bank of 12 panels and 100amp Breakers on each bank.

So wire capacity per bank is 140A, on 125A fuses and 100A Breakers. I will monitor the Temps of the wires/Breakers for a few days and see how it performs.

Those 63A Breakers were getting very hot and the way its done now everything should run under less strain constantly.

 

Edited July 9, 20224 yr by LCG

On 2022/07/02 at 11:01 PM, LCG said:

Good evening wise solar people of the web.

I have recently had a solar system installed on my house, and I feel some errors have been made but my installer totally disagrees with me.

So I am in JHB and had a system installed by a Cape Town based company which is probably my first and biggest mistake. The second mistake is the equipment installed seems to be pretty much exclusively imported by the Cape Town company and as a result no one else wants to, or knows how to work on it.

So the reason I went with this company is that I really liked the system that they supplied and the price was fantastic. I would really appreciate some constructive criticism/advice for those in the know if I may please.

So let me get right into what I have and then I'll list my concerns.

I have 24 x 455 Watt Mono Panels

2 x 5kw SRNE Inverters 

3 x 5.12kw Pytes batteries 

I am running my house and the cottage on the property from the system. In winter the property uses 55kwh/day and in summer around 35kwh/d

At present the system is generating 30-35kwh/day on a zero cloud clear sky day. I am currently using about 23kwh/day of mains supply. The batteries are going through to about 2:00am and then recharge. That charge then gets us to sun up with about 60% capacity left.

The geyser in my house is a PV element conversion from Geyserwise. The cottage geyser is the standard 3kw kwikhot on a timer from 9:00 - 10:30 and 14:00 - 14:45.

With an installed capacity of almost 11kw of panels (obviously I won't get that full amount, but I would hope for at least 75%) I am only seeing an absolute best ever peak of 6.2kw and that is for a maximum of about an hour, then I tapers off sharply again.

What time was that? Were your batteries charging? I ask because see next response.

12 of the panels are directly North facing at 30° and the other 12 are flat on the east slope which has about a 20°slope facing East.

Realistically in JHB at this time of year, is 30-35kw within spec or could I get better?

I did some maths below and adding the North and East facing panel output you could see as high as 44kWh per day. But you need to draw all that power from panels at the time that they are able to produce it, if you are drawing only 500W then that is all they'll supply. This is a good thing, imagine the solar panels pushed power into your system, where would it go?

We often temporarily get a draw of 8kw/h which is hammering the batteries. Most days the batteries are not fully charged by 16:00 when the panels are pretty much done for the day.

Why? What is causing this 8kW draw? My guess would be on resistive heating, e.g., hot water and/or stove and oven, kettle, hair dryer, electrical heater. You need to do some homework to figure out the load or draw.

The supply wires coming from each bank of 12 panels are 6mm2 but get pretty hot at mid-day.
How many amps are being pulled over those 6mm2 wires? I.e., how many panels do you have in parallel per string? What is the amp rating per panel?

I am concerned that these Wires are too thin and could be seriously restricting power if they are that temperature supplying+-3kw each approximately.....and what is going to happen in summer when the sun is really pushing? Are these Wires able to carry the supply from 12 x 455 watt panels.
Maybe, do the maths. I see at least one panel 455W panel is rated at 11.07A.

Would properly angling the 12 panels on the East Slope to face North make a notable difference or am I wasting my time?
See below for screenshot and comparison between the North and East facing arrays.

This system is probably more than perfect for 99% of the houses out there, but in my case I'm needing to get as much performance as possible to make it really work.

I'm not opposed to re-mounting the panels or running second wires from each bank, but don't want to spend unnecessarily. 

Another concern I have is that there are no battery disconnect switches anywhere on the system. I was told it's not necessary because the batteries all have power switches on, but would just like to make sure that is the case?

I have a fused disconnect between inverter and batteries I like this as a safeguard because we are talking some decent current (amp) here. My setup is configured to charge and discharge at 50A per battery for a total of 100A at 48V DC. This is well within the specs of the batteries recommended charge and discharge rate. I could push that up by 50% and be at the recommended dis(charge)rate which is still less than the peak rate. I mention this so that you can get an idea of how much current can flow. 

On other possible issue I have is that one of the DC breakes in the combiner box has tripped twice now, and it's rated at 500v and 6000A. There is also a bridge between the two incoming supply lines, so how does only one trip?

The inverters show inputs of around 50-70V and 40-70A each, this obviously constantly fluctuates.

Apologies for all the questions. I have just been spinning my wheels endlessly searching for answers on Google and was thrilled to find this community.

Please see the screenshot for your East facing panels with 20 degree slope are estimated to produce 544kWh for the month of July which works out to 17.5kWh per day. I would have to look up the angle of the sun that would make the sunlight rays hit your 20 degree panels perpendicularly to roughly figure out when they would reach peak hourly output. You can look this up but it is going to be between sunrise and midday. Then again panels are comparatively cheap when compared to inverters and batteries so maybe you actually want the early morning power from the East facing panels for your household consumption and battery charging. This depends very much on what you need.

Using -180 (North as this is a European calculator) and 30 degree sloop for your North facing panels and the estimate for July is 837kWh. That is quite the difference in output in my book...

So today everything is running nice and cool. Voltage readings on the displays are up by 20v and the amps are down too.

The next snag I'm having is that on some days the one inverter (always the same one) stops reading solar input and start supplying loads from the battery.

 

Normally at this time of the day we have almost 6kw, but the one inverter supplies about 3.2kw and the other zero.

I'm pretty sure it's a setting but you guys have any suggestions?

 

Sometimes it starts showing solar again later in the day but not always.

Edited July 10, 20224 yr by LCG

2 hours ago, LCG said:

Voltage readings on the displays are up by 20v and the amps are down too.

Wow! Those cables really were overloaded then.

2 hours ago, LCG said:

the one inverter supplies about 3.2kw and the other zero.

Err, since you've just changed the wiring, wouldn't it be more likely to be a wiring issue? Or some breaker not enabled?

Edit: IF your inverters are properly paralleled with parallel boards and cables (comms and current sharing cables), assuming an Axpert-like setup, then the two inverter should be running the same settings, EXCEPT for current related settings. These are allowed to be different between the paralleled inverters. So check settings 02 (maximum charge current), and 11 (maximum utility charge current). If you have say 30 A max one and 40 A max on the other, then you have 70 A max total.

Edited July 10, 20224 yr by Coulomb