New ground array

[pudding]

Hey, so my neighbours/family have agreed to me adding another solar array in part of their field next door, here -





Orientation just slightly south east should compliment the slightly south west facing array nicely I added most recently.

I've ordered 8x410W panels and 70m 4mm cable and some panel mounts from trade sparky, hopefully arriving this week. I've got a spare mppt input on my sunsynk inverter doing nothing and 2 spare connectors in the DC isolator, so thought it rude not to take advantage of easily adding some cheapish panels.

Plan is to build some kind of timber structure, say 6 triangular supports/brackets, with rails from 4.8m lengths of 2x4 horizontally, to have a row of 8 panels in portrait. Any suggestions on design or other cheap construction methods appreciated? Wanting to keep the height down, overall about 1m, so will be a fairly shallow angle of 35ish degrees. I'm planning on putting the structure on concrete blocks lying in the ground, and fixing the timber to these with some concrete thunder bolts, with a few more blocks on the timber frame 'feet' to weigh it down rather than digging holes and using concrete and posts.

It's about 25m from the back of the garage to where new panels will go across the field, what kind of conduit could the solar DC cable do with going in? Simple 20mm black conduit like this - https://www.screwfix.com/p/deta-corruga ... lsrc=aw.ds

Excited to crack on, hopefully all being well get it connected to by next weekend. Sure they'll be done spanner in the works though.

[spread-tee]

Why not wind in some screw piles to fix it down? they are cheap, very strong and easy to do, and I think would provide a much more secure foundation than just weighting it down with blocks. If when you need to de-commision it all you can just wind them back out again. IIRC a 90cm long screw can hold 400kg in good ground.

Desp

PS have a look at these, we have built quite a few pretty substantial garden offices on them.

https://www.ukhelix.com/garden-room-foundations/

[pudding]

Hmm, thanks will look into those a bit more. I'm sure I've got some old links from years ago when I was doing other garden projects. Any recommendations? My concern with them would be getting them all nice and straight and lined up, such that the 8ish metre long, or maybe 2x4m mounts, sits properly on them. Also, I've got blocks already so was happy to keep things simple and costs down.

[pudding]

What the general opinion of use of DC isolators for the new PV string? The Sunsynk inverter has its own PV isolator switch that disconnects the PV, and I've read a few comments on FB groups saying that some avoid using DC isolators if possible as it introduces more possible points of failure/fire. So, it's tempting to just put the MC4 connectors straight on the ends of the DC cable from the panels and just connect straight to the inverter. Good idea, or terrible idea?

Here's the current Kraus&Naimer DC isolator with the 2 spare terminals, L2&3, for a new string.

[Joeboy]

What the general opinion of use of DC isolators for the new PV string? The Sunsynk inverter has its own PV isolator switch that disconnects the PV, and I've read a few comments on FB groups saying that some avoid using DC isolators if possible as it introduces more possible points of failure/fire. So, it's tempting to just put the MC4 connectors straight on the ends of the DC cable from the panels and just connect straight to the inverter. Good idea, or terrible idea?

Here's the current Kraus&Naimer DC isolator with the 2 spare terminals, L2&3, for a new string.

From a practical POV it is worthwhile having DC isolator inline so you can simply turn off the incoming DC for any maintenance rather than popping live MC4's?

[dan_b]

410W panels - amazing! Looking forward to seeing this develop...

[resybaby]

I have a Synsynk invertor and find the inbuilt DC isolator rubbish. I wish i had inline isolators (would fit them if essy enough?)
Sunsynk DC isolator Is very clunky, and often when i check the panels in to morning they are showing nothing 'incoming' from the strings. If i flick the switch off and straight on again, hey presto usually some watt magically start arriving.
Would fit some by the strings at least anyway in your situation i think. So you can isolate locally if required.
But do note, im not a sparky and am very new to all this solar.

[Stinsy]

Hey, so my neighbours/family have agreed to me adding another solar array in part of their field next door, here -





Orientation just slightly south east should compliment the slightly south west facing array nicely I added most recently.

I've ordered 8x410W panels and 70m 4mm cable and some panel mounts from trade sparky, hopefully arriving this week. I've got a spare mppt input on my sunsynk inverter doing nothing and 2 spare connectors in the DC isolator, so thought it rude not to take advantage of easily adding some cheapish panels.

Plan is to build some kind of timber structure, say 6 triangular supports/brackets, with rails from 4.8m lengths of 2x4 horizontally, to have a row of 8 panels in portrait. Any suggestions on design or other cheap construction methods appreciated? Wanting to keep the height down, overall about 1m, so will be a fairly shallow angle of 35ish degrees. I'm planning on putting the structure on concrete blocks lying in the ground, and fixing the timber to these with some concrete thunder bolts, with a few more blocks on the timber frame 'feet' to weigh it down rather than digging holes and using concrete and posts.

It's about 25m from the back of the garage to where new panels will go across the field, what kind of conduit could the solar DC cable do with going in? Simple 20mm black conduit like this - https://www.screwfix.com/p/deta-corruga ... lsrc=aw.ds

Excited to crack on, hopefully all being well get it connected to by next weekend. Sure they'll be done spanner in the works though.

SWA is much easier in these situations than “solar” cable because you can basically sling it where you like, you can bury it directly etc and is the standard choice for this kind of installation. I wouldn’t use copex (or whatever) flexible conduit, I’d suggest twin-wall duct which looks a bit similar but is substantially more durable.

You can go for fence posts and pressure-treated 4x2 if you like. Just make sure you treat all the cut ends, use good quality galvanised bolts, and build in a structurally-sound way. If you want to do some drawings of what you’re thinking we’ll be happy to give notes. Just be aware that wind loads will be substantial. Alternatively have you considered scaffold poles or Unistrut?

[pudding]

Ah, already ordered 70m of the solar cable, so twin wall conduit it is! Anything in particular or any twin wall that google comes back with?

Here's a rough sketch of the initial timber frame plan. I thought about scaff and uni-strut, but the timber just works out way cheaper from what I could see. was hoping to keep total costs under £1000.

Plan was to use pressure treated 100x100 vertical posts and 100x50 for the horiontal 'sole plate' and diagonal brace and 'rails', glued and screwed using the gorilla PU adhesive I've already got.

[Andy]

Just be aware that wind loads will be substantial.

As an idea, I have 16 panels and they are bolted in to 3 piers of concrete which add up to 3 tons. That's on an aluminium frame.