Ground mount Solar PV

jaredGalen

Looking for opinions on placement of groundmounted 15 x 400w panels. Roof mounting is a no go.

Quote after grant is about 13k.

The purple line is south facing, but there is a good 80m run back to house and connections.

What should I consider with such a long run?

Should I consider altering the pure south aspect?

Bakka

https://www.boards.ie/discussion/2058255298/ground-mount-solar-pv

I have a ground mount 9.1kwh ---- 20 Ja solar 455 system . I went with an orentation of 150 degree angle. 90 is due East. 180 due South. So 150 is more South than East. I didn't go totally 180 South as there is large trees which would have blocked generation in a low lying winter sun. I also prefered the physical look of a more straighter line even though it is ever so slightly angled, it looks straight. You also seen to have trees/bushes etc directly due South. Are they tall, will they cause shade etc? If they do that will affect output from your panels. I would probably move the purple line to the blue line and have it at the same angle as the purple if it's possible.

jaredGalen

Thanks.

Those are 2 large trees that would need to go at the purple line.

Would need to go also for blue line placement. Have another to the west that would possibly block winter time sun of both.

The long cable run and associated losses makes the optimal placement a topic of concern, and what trees to knock. 🤦🏻‍♂️

slave1

If you are spending this effort and outlay then consider tiltable mount setup to allow you max high summer and low winter generation, most fixed tilts will be 45degrees but it's 60degrees for June and 14degrees for January to gain optimal generation

Citizen Six

https://www.boards.ie/discussion/comment/119363240#Comment_119363240

Can you just adjust position rather than cut down two trees? Seems to defeat the purpose of renewable energy if you cut down trees for it.

Punchin A Keyboard

I would be more thinking of a east west split either side of the hedge at the end of the blue line as a good option

DC999

1 - split: Yeah, E/W split would give a good spread over the day. Not sure if those are your sheds and have any machinery / farming stuff in them that would be used during the day. Not suggesting you're a farmer just because it's not a city housing estate :) But same principle for using power in morning and evening for anything. Doesn't need to be E/W split. Could be S and W if don't need much power in morning. Or E and S if don't need power in evening...

2 - losses based on distance: In terms of the cable length, measure the route yourself (for distance) and ask installer to confirm the gauge of wire needed so the losses are kept to a minimum balancing with the cost of the cable. f cable is too small it builds up heat meaning it's losing energy so it's wasted. And I'm assuming it can also do bad things to kit connected to it if undersized.

Bear in mind you may well want to add solar capacity in time so best to leave spare in the cable as a lot of work to bury a cable 80m and cost. You can 'over panel' to get more than a 6kwp system. Without that capacity you'd need to run another cable.

The Will Prose website https://diysolarforum.com/ has stuff on how to see the % of losses across cable runs based on distance (there's a formula once you know the distance and either amps or voltage - can't recall which). If it was me I'd double that against what the installer was telling was the right cable thickness - it's your system losing efficiency forever so worth seeing are they 'cutting a corner'. @irishchris has a ground mount afaik and did a write up somewhere on this forum about it. I've a roof mounted so only spewing out what I've read about ground mounts.

3 - roof mounting is a no go you said:

Mind me asking why that is? Asking in case it's an option once you get the ground mount costs to compare. Ground mount will likely cost a lot more unless you can DIY a lot for the trench, cable run, frame build... Or have someone giving you a decent rate for that. Even price of metal or heavy duty timber for the frame will cost a whack. Looks like there is a lot of rook space but hard to tell what's the house, garage. Is shed to right yours and is that a circular roof....

bullit_dodger

I'd also be curious on #3 above from DC999. If you have a roof that you can mount onto, this is invariably the best solution.

As an alternative to #2 above, you could go with 2 or even 4 panel micro-inverters down at the ground mount. That way you would only have to run a long AC cable rather than DC cable. AC is less prone to losses over distance than DC and you can do the power transfer with a smaller (i.e. cheaper) cable.

saccaromyces

Hi all, Had guys out to fit panels, they said it would be a waste to put on roof because of shadows and having to split them, and the west side would give very little in winter.

They sugested a ground mount and couldn,t understand when I got survey this wasn,t suggested. I went back to co, who where not very happy with me changing now. now there quoting 21k before grant for, 18x 400wp panels

Ground mount system, sofar 6kw inverter, 2x 2.4kwh batteries. Seems expensive, help

poker--addict

shop around, you will get idea of reasonable prices and advice.

irishchris

https://www.boards.ie/discussion/comment/119515547#Comment_119515547

Absolutely shocking quote. Don't accept that and shop around. A lot of companies don't like the time labor and involved in ground mounted systems and can save yourself a lot if not going self install offer that you agree to do a lot of the digging trenching work to them and they will lower the quote often substantially.

hydrus21

Apologies to OP for coming in here.

Is anyone familiar with a ground mounted array system that can be dismantled within an hour or so?

The property is very exposed to the Atlantic storms and is empty over the winter months.

I feel roof mounted panels in this location is asking for trouble.

Thanks

DC999

https://www.boards.ie/discussion/comment/121532481#Comment_121532481

There is no removing a solar setup in an hour. There are high voltage cables from the panels. That = danger to remove and reinstall post a storm.

If your roof stays on, the panels will stay on. Worst case, you could brace the rafters in the attic to add additional support.

I know of homes in Kerry within a few hundred meters of the sea with solar panels. And people have had solar thermal panels for years too in windswept areas. They can look like solar pv panels. But they are the ones for hot water

bullit_dodger

https://www.boards.ie/discussion/comment/121532781#Comment_121532781

Yeah, I'd agree with DC999 there. The rails which the panels are afixed to are usually secured by multiple "6 inch" screws into your rafters. Never heard of anyone on these forums (and I've been here 2-3 years) ever having an issue with wind and panels. Remember, they are effectively flush with the roof. Just elevated 2-3 inches from the slates. If they were angled, or more away from the roof where wind could catch underneath then yeah maybe, but not if it's normally installed. SEAI also have a regulation that they must be installed more than 50cm from any edge. Generally it's no harm to be worry about these things, but in this case you can rest easy.

BTW, a ground mount is much more exposed and subject to higher wind loading usually.

graememk

It has been a bit breezy the last few days isn't it?

I'd echo what the rest are saying, if your roof isn't coming off, your panels won't be either.

Ground mount would be a bit more vulnerable but generally they are very well secured. If really concerned, there is the plastic tubs that you can ballast down as required and sit low to the ground

hydrus21

https://www.boards.ie/discussion/comment/121533709#Comment_121533709

I have seen these tubs but they would need to be spaced out to enable access to each panel which would take up a lot of space.

I guess the largest panel and tub would be the best use of space.

I had assumed that dis-connecting each panel in turn would render the system safe until re-connection.

Have I been watching the wrong youtube vids?

graememk

https://www.boards.ie/discussion/comment/121534804#Comment_121534804

Well the idea of the tub is to not move them at all. If you put enough ballast in them they won't go anywhere.

bullit_dodger

https://www.boards.ie/discussion/comment/121535035#Comment_121535035

Just incase it wasn't clear, Graeme's talking about something akin to this.

Flat Roof Mounting Kit for Solar Panels (voltaconsolar.com)

Not a huge fan of these myself - they have their uses, but it's a relatively shallow angle which will do extremely poorly in winter. Much better to get a proper cemented structure in place where you can angle at 30-40deg from the horizontal.

graememk

https://www.boards.ie/discussion/comment/121535218#Comment_121535218

Just make the ground a bit more sloped 😂

But for ease of install, they are so easy, no ground works, almost considering some myself. If you have the garden space.

MakersMark

These are holding down my 16 panels in a very windy environment.

GSE Ground mount system.

hydrus21

I have the ground space and like the low position and the enclosed sides to prevent the wind getting under.

Agree that the 15 angle is too low and I would modify in some way to default to 30 ish.

In a winter storm I would worry less with this ground mount set-up .

The property is undergoing renovation and I was considering a modular system so I could start with water heating and gradually expand and

maybe one day acheive off-grid.

Gratefull for any advice.

Thanks

graememk

https://www.boards.ie/discussion/comment/121535419#Comment_121535419

But if it's empty over the winter months, you don't need a higher angle.

4kwp at 15 degrees , due south output is 2924kWh

4kwp at optimal angle(32 degrees) is 3002

78 kWh difference, if that was all exported at 20c that's a difference of 15 euro a year.

hydrus21

Thanks. I think I understand your workings.

The house prior to renovation had no insulation whatsoever hence being empty in the colder months.

After the work is done I hope that more use is made of the house and will plan the energy usage to that.

graememk

You can see monthly/yearly estimates using the jrc website (it's pretty spot on)

https://re.jrc.ec.europa.eu/pvg_tools/en/#PVP