Advice for DIY Solar Install.

[Bigvanish]

Good evening,


I am heading down the path of a DIY solar install in a bid to avoid the energy price hike coming when my current deal ends!. I am hoping a kind and informed soul may be happy to share some advice regarding my setup as I want to ensure the build is safe!.


My house / garage suffers from shading issues due to trees and a neighbouring property. I intend to install my setup on a ground mounted frame in a small fenced field at the rear of my house. This location has no issues at all with shading.



I have purchased 10x540w JA Solar panels

(datasheet)

https://cdn.shopify.com/s/files/1/0...0-555_MR_Global_EN_20210531A.pdf?v=1668948978


and a Solis 6kW Hybrid 5G Energy Storage Inverter

(datasheet)
https://cdn.shopify.com/s/files/1/0...-af06-4462-b7f5-ca727b726840.pdf?v=1675337102
If my interpretation of the datasheets is correct, wiring these panels in series should allow me to run about 500v DC and 13amps in optimum conditions. I realise the average output will be considerably less but I want to ensure the system can meet optimal requirements.

I intend to install the inverter and battery setup in the garage which is about 120 meters from the panels. With this in mind my query is regarding DC cable size and ducting. Will 6mm2 solar DC cable in a ducting be sufficient over this 120m run? If so, is non perforated twin wall land drainage ducting, say 50mm, suitable for such a setup? lastly, assuming this is suitable, is there any recommended depths for the burial of such ducting/cable.

I am aware of the need to seek the approval of the DNO given the solar capacity and want to ensure the basic install approaches industry standards, even if installed by an enthusiastic beginner!

Many thanks for your help.

BV

 

[Bigvanish]

So I researched the subject and discussed with a local Electrician. 70 meters of cable buried 750mm down and marked up with tape. My poor garden is in tatters

 

[Bigvanish]

 

[bladerunnerpv]

Best of luck with your build. What does the voltage drop work out at due to the 70m of cable?

 

[Bigvanish]

Best of luck with your build. What does the voltage drop work out at due to the 70m of cable?

Thanks for the well wishes!.

In terms of the voltage drop. The 10 panels are ground mounted out in the field where there hopefully should be zero issues with shade . According to the datasheet each panel has an maximum operating voltage of 50v and 12 amps. They will be connected in series and connected via 6mm2 solar cable. If my sums are correct (well if the the below calculators are correct) , I think I should be looking at about about 1.5% or about 75W.




https://midsummerenergy.co.uk/voltage-drop-calculator
and

https://photovoltaic-software.com/solar-tools/voltage-drop-calculator-dc-ac

 

[bladerunnerpv]

Not much at all then!

And I had job at the back of my mind that I really ought to work out voltage drop from from loft to shed in case it was too high!

I look at midsummers site fairly often but have missed that calculator as its in the off-grid sister site ! Chuckles to self! Thanks for the link to the other one too

In case you're not aware of it they do a free PV estimating tool easy-pv, worth a look if you've not seen it.

Voc is 49.6 and Isc 13.86 at STC for JAM72S0-540/MR. Voc will increase and Isc will drop at temperature less than STC, guess you need to look at the extremes?

 

[Chewbacca]

For solar 1% VD is recommended, but 75W, not the end of the world...

 

[Bigvanish]

Not much at all then!

And I had job at the back of my mind that I really ought to work out voltage drop from from loft to shed in case it was too high!

I look at midsummers site fairly often but have missed that calculator as its in the off-grid sister site ! Chuckles to self! Thanks for the link to the other one too

In case you're not aware of it they do a free PV estimating tool easy-pv, worth a look if you've not seen it.

Voc is 49.6 and Isc 13.86 at STC for JAM72S0-540/MR. Voc will increase and Isc will drop at temperature less than STC, guess you need to look at the extremes?

That’s a great tool, thank you.

Not much at all then!

And I had job at the back of my mind that I really ought to work out voltage drop from from loft to shed in case it was too high!

I look at midsummers site fairly often but have missed that calculator as its in the off-grid sister site ! Chuckles to self! Thanks for the link to the other one too

In case you're not aware of it they do a free PV estimating tool easy-pv, worth a look if you've not seen it.

Voc is 49.6 and Isc 13.86 at STC for JAM72S0-540/MR. Voc will increase and Isc will drop at temperature less than STC, guess you need to look at the extremes?

thanks for the heads up on the Easy Pv tool. I had a play and it’s a really straight forward tool to use.

In terms of the the temperature calculations. My inverter is a Solis 6kw hybrid inverter with a maximum DC input voltage from the PV Array of 600v and 8000w. It can get pretty cold up in the North of Scotland. I used a temperature as low as -20 and I am calculating a maximum voltage of 550v or so on such conditions. Below the maximum input voltage. I have looked also at temperatures up to 35 degrees Celsius but if my reckoning is correct we are still within voltage and amp limits. I think under bright and ideal operating conditions I should be sitting towards the upper end of the Solis data sheets indicated input limits for voltage and amp and for the most part sitting mid to upper end of comfortable operating numbers. I certainly hope my sums make sense. The entire process has been a 6 month research programme that has consumed my spare time!

 

[bladerunnerpv]

You're welcome bigvanish I've found it really useful for trying lots of what-if variants, different inverters and panels etc, to improve my understanding and use the data for working out payback times. Warning - it can be quite addictive too!

It doesn't yet include anything for scheduled battery charging from grid overnight, would be nice if it could.

You could also try PVGIS which is also free.

Looks promising

 

[Bigvanish]

And some photos of the ground mounting frame. It is still to be sheeted and flashings added but you get the idea!

 

[Bigvanish]

lots of hours went into this

 

[Bigvanish]

lots of hours went into this

 

[wytco0]

lots of hours went into this

I bet but it looks like a great setup.

I have recently used some of the ballasted ground based GSE mounts from Midsummer wholesale and they are very impressive https://midsummerwholesale.co.uk/buy/gse-ground-mount, might be worth a look when you add more panels (you probably will, I am now on my 3rd increment)

 

[Bigvanish]

I bet but it looks like a great setup.

I have recently used some of the ballasted ground based GSE mounts from Midsummer wholesale and they are very impressive https://midsummerwholesale.co.uk/buy/gse-ground-mount, might be worth a look when you add more panels (you probably will, I am now on my 3rd increment)

Thanks for the link mate. I think that would save a hell of a lot of work!. I think if there's any more upgrading in the future it would be an additional 4.8kw battery. This would allow us to run over night, completely on batteries (based solely on house current overnight demand. I will see if I can get the first bash completed and past a DNO before getting to excited about more haha

 

[Bigvanish]

And the garage side wired up. I hope to get a sparky in for a look over everything to make sure its safe and wont set my garage on fire!

 

[Bigvanish]

PS, For the qualified installers out there, what's your thoughts on the metal conduit clips around the black plastic conduit, from an earthing point of view?. At present the main galvanised conduit, carrying the PV cables into the garage is earthed back to the consumer unit at the main garage feed. The metal saddle clips pinning the plastic conduit are not earthed (pinning the 48V dc cables from the inverter to the fuses and onto the battery). It would probably easier to replace with plastic clips than try to earth each metal one. I am not sure if this would be an issue. Thanks, Big

 

[roys]

PS, For the qualified installers out there, what's your thoughts on the metal conduit clips around the black plastic conduit, from an earthing point of view?. At present the main galvanised conduit, carrying the PV cables into the garage is earthed back to the consumer unit at the main garage feed. The metal saddle clips pinning the plastic conduit are not earthed (pinning the 48V dc cables from the inverter to the fuses and onto the battery). It would probably easier to replace with plastic clips than try to earth each metal one. I am not sure if this would be an issue. Thanks, Big

No need to Earth the conduit clips.

 

[Bigvanish]

No need to Earth the conduit clips.

Brilliant, thanks very much for the info.

 

[roys]

Your ground mount frame looks impressive

 

[Bigvanish]

Your ground mount frame looks impressive

Thanks very much. I am hopeful she wont blow away anytime soon!