Hi All, I'm currently awaiting my 21 X 330W/48V panels, 2 Axpert 4KW inverters and 2 PylonTech Lithium Ion 3.5kW - apparently there is a shortage country wide. In the mean time I'm installing the infrastructure. This is a DIY project on a tight budget and looking to minimize grid use. Although I am a sparky by trade and know Mr Voltare', Mr Ampere' and Mr Watt quite well, I've never done this before so I'm very much a newbee.

I have a few questions that have come up during this installation exercise that I'm really battling to get answers to so if anyone could help with advice it would be appreciated.

Question 1: The 21 panels will be connected in 7 array sets of 3 panels per string (144V and 7A per string in optimal conditions). The inverters will be paralleled as master and slave.  Can I parallel out all 7 arrays and share the panels output equally between the 2 Axperts or should I dedicate say 3 arrays to the master and 4 to the slave?

Question 2: Can I use AC surge protection Type 1 and 2 (SPD) 220V AC, for the panels (144V DC)?

Question 3: Would normal insurance cover an installation like this under home owners?

 

Edited April 26, 20197 yr by KevinM

4 hours ago, KevinM said:

Hi All, I'm currently awaiting my 21 X 330W/48V panels, 2 Axpert 4KW inverters and 2 PylonTech Lithium Ion 3.5kW - apparently there is a shortage country wide. In the mean time I'm installing the infrastructure. This is a DIY project on a tight budget and looking to minimize grid use. Although I am a sparky by trade and know Mr Voltare', Mr Ampere' and Mr Watt quite well, I've never done this before so I'm very much a newbee.

I have a few questions that have come up during this installation exercise that I'm really battling to get answers to so if anyone could help with advice it would be appreciated.

Question 1: The 21 panels will be connected in 7 array sets of 3 panels per string (144V and 7A per string in optimal conditions). The inverters will be paralleled as master and slave.  Can I parallel out all 7 arrays and share the panels output equally between the 2 Axperts or should I dedicate say 3 arrays to the master and 4 to the slave?

Question 2: Can I use AC surge protection Type 1 and 2 (SPD) 220V AC, for the panels (144V DC)?

Question 3: Would normal insurance cover an installation like this under home owners?

 

Hi, and welcome to the forum. 

1. Each inverter will have it's own set of panels. 3 string on the one and 4 string on the other would be fine. 

2. You need to use DC surge protection Type 1 and 2, depending on your are, for the panels. They're more expensive though and come in 600V or 1000V variants. 

3. Yes, as long as you install as per regulations and sign a COC for it. 

 

5 hours ago, KevinM said:

3 panels per string (144V and 7A per string in optimal conditions)

That's awfully high for a an inverter model with a 145 V Voc. The MPPTs usually derate above 130V, and might provide only 250 W at 144 V. You'd be better using pairs of those monster panels, and order an even number of them. The Axpert charge controllers seem to be designed for 60 cell panels, which are usually 250 - 300 W. If you could get say 21 300 W panels (and confirm that they are 60 cell) that would be much less wiring.

As already mentioned, the two inverters must have separate panels; the Solar Charge Controllers are not isolated. 

Edited April 27, 20197 yr by Coulomb

3 hours ago, SilverNodashi said:

Hi, and welcome to the forum. 

1. Each inverter will have it's own set of panels. 3 string on the one and 4 string on the other would be fine. 

2. You need to use DC surge protection Type 1 and 2, depending on your are, for the panels. They're more expensive though and come in 600V or 1000V variants. 

3. Yes, as long as you install as per regulations and sign a COC for it. 

Thank you very much for the your 3 answers SilverNodashi. I'll take your advice with the current design which your answers to 1 and 3 confirm. On question 2, I've got some never been used 230VAC T1&2 SPD's that have been lying around for a while, what's the worst that can happen? The T1 is made to take a higher powered surge but is slower than the T2 which can't handle the peak of a large surge. As I understand the theory correctly these things only work or self destruct when there is a voltage surge - or am I missing something? 

5 hours ago, Coulomb said:

 

That's awfully high for a an inverter model with a 145 V Voc. The MPPTs usually derate above 130V, and might provide only 250 W at 144 V. You'd be better using pairs of those monster panels, and order an even number of them. The Axpert charge controllers seem to be designed for 60 cell panels, which are usually 250 - 300 W. If you could get say 21 300 W panels (and confirm that they are 60 cell) that would be much less wiring.

As already mentioned, the two inverters must have separate panels; the Solar Charge Controllers are not isolated. 

Thanks Coulomb, your response regarding separate panel circuits for each inverter has answered a pressing question. I agree with you in that I have had my reservations about the high Voc that may be generated in ideal conditions. My supplier warned me against taking the 350W Canada half cell units for this very reason. Hence I chose the 330W JA panels which I got at a really good deal of only ZAR 1750ea incl vat (about Au$ 180ea). I'm expecting delivery of 12 on the 2nd May and the rest later, so I'm pretty much stuck with them.

I think I'll play this one by ear as my north facing roof is ideally suited for exactly 21 1X2meter panels (chimney gets in the way of a 22nd panel). On top of that I'm running a 20m 3 core 6mm2 armored cable which is at its limit of 46A using one core as a common negative. I want to avoid purchasing another cable if I can help it so going in at a lower voltage will add cost. (The cable was left over after I hopelessly over ordered for the AC side other wise I would have used a 6mm2 4 core).

Coulomb, I noted that you're from Brisbane which means we're along similar latitude (Johannesburg). With winter fast approaching how do you find the solar generation on a cold clear winter day compared to a hot clear summer day? 

10 hours ago, KevinM said:

Coulomb, I noted that you're from Brisbane which means we're along similar latitude (Johannesburg). With winter fast approaching how do you find the solar generation on a cold clear winter day compared to a hot clear summer day? 

I've recently changed my panel setup, so I'm not in a position to say how it compares as yet. In winter you obviously suffer most from the shorter days. I seem to get less fade from the heat in Winter, but that's only a small effect compared to the short days (some 10 hours compared to some 14, many of those are low production, obviously). I'm also plagued by shading in Winter. That's the reason for an extra 6 panels on my carport, angled up at 45° to nearly optimise for Winter. They are on the south side of my house (hence the need for stands, so I thought I might as well give them some extra tilt). It seems to be working out quite well. This morning when I checked, the 6 strings including the new carport panels were producing a fair bit more power than the other 8 strings, some of which have the winter shading issue (the shading started showing up a few weeks ago, so it's a lot more than winter season that has at least some shading).

Sorry I can't provide more concrete numbers.