Help with my setup

[Andy1733]

Hi, I'm new to solar PV and thought the best way to learn is joining a forum. I've been considering solar for the past 12 month and now I have the funds I have started purchasing items o would need.

Location. I have a STD 1930s 3 bed semi. In my garden I have 2 outbuildings. One 140 block garage 32ft X 10ft and a workshop 20ft X 20ft Alos built from 140 blocks. These form a L shape approx 40ft from my house. Roof is corrugated tin and it's south facing.
Armoured cable runs to the garage from my house consumer unit. Into a garage cu.
I have just received 15 new renesola jc255m panels. Each panel is 255w 37.5ov and 8.8ah

I have also just purchased the renusol mounting kit for the above panels. I plan to mount them 3 wide X 5 deep (15 panels) on the garage section of the roof.

Theses will go to the Solis 3.6k-48es hybrid inverter.

Question I have is. I plan to run the panels in series.
Which is best.
3x5 panels. (One I was going to use)
5x3 panels.
2x7 panels. (Only use 14 panels)
Does it make a difference?
Also The Solis inverter accepts 2 string inlets from the solor panels. Should I use both or just one?
Tbh I have loads of questions.

 

[binky]

Tbh I have loads of questions.

at the risk of sounding rude, you havn't a clue

OK, Solis have 2 MPPTs so use both of them, the strings do not have to have the same number of panels on each 8x37.5 (is that the VoC figure) is 300V so well within the Solis spec of 600V VoC will be a bit higher but still well within spec.

What is size is the cabe feeding the garage? What RCd protection do yuo have on the boards supplying the garage - this is an important safety question.

 

[Andy1733]

at the risk of sounding rude, you havn't a clue

OK, Solis have 2 MPPTs so use both of them, the strings do not have to have the same number of panels on each 8x37.5 (is that the VoC figure) is 300V so well within the Solis spec of 600V VoC will be a bit higher but still well within spec.

What is size is the cabe feeding the garage? What RCd protection do yuo have on the boards supplying the garage - this is an important safety question.

Thanks for the prompt reply Binky.
Yeah the 37.5 is the voc figure.
The cable that feeds the garage I believe is 16mm. Would need to check. The board in the garage has a 100a main switch with 2 63a RCD.

 

[binky]

big board for a garage! Cable size should be fine. We look for only 1% power losses on solar to prevent voltages floating too high, where as we would normally allow 3% for power distribution.

OK you don't want to sharing either of those RCDs with the solar, reason being that grid tied inverters can take 3 seconds to shut down - official spec. In reality they shut down faster than that, but we can't guarantee it. RCDs need to shut down in miliseconds to protect people from being killed, so the RCd could be tripped out, but your solar could still kill you. It may be possible to fit an MCB not linked to those RCDs if you have a 'high integrity board' (has 3 neutral bars), failing that you may be able to fit RCBOs for individual circuits and get rid of the 2 RCDs. The solar is better on an MCB, not on a RCD or RCBO if your cable run will allow that, ie surface mounted between the inverter and board. You don't see it so much these days, but the relays in the inverter can 'chatter at start up and shut down, which RCDs don't like and can therefore trip out losing you output from the system.

 

[Andy1733]

Thanks for the prompt reply Binky.
Yeah the 37.5 is the voc figure.
The cable that feeds the garage I believe is 16mm. Would need to check. The board in the garage has a 100a main switch with 2 63a RCD.

big board for a garage! Cable size should be fine. We look for only 1% power losses on solar to prevent voltages floating too high, where as we would normally allow 3% for power distribution.

OK you don't want to sharing either of those RCDs with the solar, reason being that grid tied inverters can take 3 seconds to shut down - official spec. In reality they shut down faster than that, but we can't guarantee it. RCDs need to shut down in miliseconds to protect people from being killed, so the RCd could be tripped out, but your solar could still kill you. It may be possible to fit an MCB not linked to those RCDs if you have a 'high integrity board' (has 3 neutral bars), failing that you may be able to fit RCBOs for individual circuits and get rid of the 2 RCDs. The solar is better on an MCB, not on a RCD or RCBO if your cable run will allow that, ie surface mounted between the inverter and board. You don't see it so much these days, but the relays in the inverter can 'chatter at start up and shut down, which RCDs don't like and can therefore trip out losing you output from the system.

Yeah mate it's a big board though I have the garage, workshop and koi pond all linked to it. I will check the board when I'm home though I can't see it having 3 banks of neutrals. Failing that I have plent of cable slack so a MCB would work

 

[Andy1733]

Yeah mate it's a big board though I have the garage, workshop and koi pond all linked to it. I will check the board when I'm home though I can't see it having 3 banks of neutrals. Failing that I have plent of cable slack so a MCB would work

Well the day gets better. 3 neutral bars it has, so looks like a high integrity board to me . The way I have it set up is.
The main switch is on numer one neutral bank on its own.. The first rcb is on the 2nd neutral bank. and the 2nd rcb on the 3rd neutral bank.
Should I move the main switch to either of the 2nd or 3rd neutral bank or just put the solar with the main switch?

 

[binky]

Put solar with main switch

 

[Andy1733]

Put solar with main switch

Thanks Binky. You have been extremely helpful.
Tbf I have a best mate who upto retirement was fitting solar. Though sadly he had/has cancer and has just finished a 4 week Radium treatment course so even though he wants to help I feel guilty asking him so the more I can learn the easier it will be to take the load off him. Plus o can delay installation until he's recovered more.

Regard further questions. I have a keto battery disconnector coming and. Planning on installing around 10kw of battery backup. I've always planned on the pylontech batteries but I've just seen that voltacon do some 2.4 and 5.2 batterys with very sim spect to the pylon one's. Do you know anything about voltocon battery's? Are they any good or am I better waiting for stock levels of pylontech to come into the country

 

[binky]

Not familiar with Voltacon, but first fitted Pylontech about 5 years ago. They seem well made, I prefer the older style units, much easier to handle.

 

[Andy1733]

Not familiar with Voltacon, but first fitted Pylontech about 5 years ago. They seem well made, I prefer the older style units, much easier to handle.

Does it make any difference how the modular battery bank is made up? IE 4X 2.4kw Or 3X 3.5kw or 2x 5.12kw. Apart from weight or are the newer pylontech force the way to go?

 

[binky]

The new ones are effing heavy, I also had one of those develope a fault. It was replaced under warranty, but...

 

[Andy1733]

The new ones are effing heavy, I also had one of those develope a fault. It was replaced under warranty, but...

Thanks again. You have been extremely helpful.

 

[Andy1733]

Hi all (Binky).
My thoughts have now turned to cables.
Does anyone have any recommendations for brand or suppliers for the cable and connectors. There are plent of cheap stuff out there but cheap is not what I want
Am I right in thinking the mc4 connectors take 4mm and 6mm? Though it looks like the Solis is specified 6mm

 

[binky]

MC4s take 4and 6mm cable. They aren't expensive anyway, but do buy a pair MC4 spanners to ensure you tighten the glands up properly - the most common cause of failures in solar arrays. Yiu should also use an MC4 crimp tool, but they are expensive (mine were around £200), and you can manage with a pair of pliers and a bit of care.

 

[Andy1733]

Thanks Binky. I had a visit from the electrician yesterday as he's feeling a lot better though still on morphine pads and tablet for the pain. He mentioned he has the spanner and crimping tool for the mc4.
I've decided with some advice from the sparky to replace the consumer unit in the garage. It was a plastic mk and whilst I had room for the PV system it's prob wise to update everything and clean up whilst I'm doing the install.

 

[Andy1733]

Update for Binky.
Day 1 of install.
Fitted new 6x4 backing board to garage wall covered with fire rated boarding.
Labeled the snakepit of wires in anticipation of new board installation (Tuesday)
Mounted all the new components, inverter DC and AC switches, meter, ect to the board.
Mounted the brackets and 1st 8 panel string to the roof. Dropped a cod with the amount of brackets . I knew I needed 24 centre clips and 12 end clips. Then went and ordered 32 mini rails. Doooooooo..
Contacted solar sparky and said dispatch Monday morning.

Found out whilst cleaning up the snake pit that the main cable from the house is only 10mm. Would you recommend I upgrade to 16mm?

Am I correct in thinking I need to send a g98 form application within 28 days of completion? Would I need to Inc the battery's I intend to fit even though I don't yet have them?
Also Do I need to get a certified solar pv installer to certify/commission the installation or can my electrician cert the installation?

Day 2 should be Tuesday-- as the work load yesterday really took it out of my electrition

 

[binky]

If it's a hybrid inverter, they aren't concerned about batteries, it's batteries connected as a stand alone system they don't like. Install should be notified within 28 days, G98 should be fine if inverter is 16a.

Upgrading the cable might be worth doing, the less resistance on the system the more efficient it will be.

 

[Andy1733]

Thank you m8. I can't thank you enough

 

[Andy1733]

Hi all. Ive got everything up and running. Apart from the Solis data logging stick.
Ive downloads the Solis cloud app and tried to connect via my mobile phone. I just keep getting "connection failed".
Am I missing something or can Anyone help?

 

[binky]

Hi all. Ive got everything up and running. Apart from the Solis data logging stick.
Ive downloads the Solis cloud app and tried to connect via my mobile phone. I just keep getting "connection failed".
Am I missing something or can Anyone help?

You need to link dongle to your internet, then the solis portal, then link phone app to portal. It's a prat!