Panels overheating or simply not suited for hot weather?

[sharpener]

What I dont want though is somebody to arrive with a bunch of panels and go "Ahhh, but you've got xyz roof tiles we cant do that!!" because I know I dont have a cookiecutter roof. I'd rather people not wing it on the day.

Well from the pic it certainly looks an awkard roof! You will defo need the two separate trackers for the different W and S aspects.

Also with that ratio of PV to battery capacity you will be using a lot from the grid. The last two days there has not been enough sun to fully charge my paltry 10kWh with 6.9 kW of PV.

[dan_b]

A SolarEdge system could be good there with those different aspects.

[sharpener]

A SolarEdge system could be good there with those different aspects.

I'm not convinced. The two aspects are well catered for just with the two MPPTs, in the absence of shading.

By coincidence I was watching this video yesterday and it demonstrates conclusively IMO that the integral bypass diodes are usually enough and the merits of EnPhase and SolarEdge are overstated.

And personally although I have a small amount of shading on both my arrays I would not want a permanent 2% performance penalty and the worry that something will go wrong up on the roof. Let alone the extra cost.

[Tay]

What I dont want though is somebody to arrive with a bunch of panels and go "Ahhh, but you've got xyz roof tiles we cant do that!!" because I know I dont have a cookiecutter roof. I'd rather people not wing it on the day.

Well from the pic it certainly looks an awkard roof! You will defo need the two separate trackers for the different W and S aspects.

Also with that ratio of PV to battery capacity you will be using a lot from the grid. The last two days there has not been enough sun to fully charge my paltry 10kWh with 6.9 kW of PV.

Lots of things are dependant on the system and realistically what I can get out of it, I'm still trying to sell the upper most fencing as an option for some meaty panels but it involves losing a chunk of privacy if I want to tuck them away against the fencing. for a meagre 4M of fence I could effectively double the roof PV.

The PV to storage ratio isnt great for topping up batteries, but purely from a cost point of view I have a 5hrs window to recharge them from mains at a less than a 3rd of the cost vs peak. Not ideal but options arnt really jumping out. Even in the summer the PV is only likely to cover 30-40% of the battery charge then relying on the cheap rate at night.

I'm also a little bit worried that in winter my South aspect might suffer from shading from the neighbours roof thus making a terrible roof even worse.

[Tay]

A SolarEdge system could be good there with those different aspects.

I'm not convinced. The two aspects are well catered for just with the two MPPTs, in the absence of shading.

By coincidence I was watching this video yesterday and it demonstrates conclusively IMO that the integral bypass diodes are usually enough and the merits of EnPhase and SolarEdge are overstated.

And personally although I have a small amount of shading on both my arrays I would not want a permanent 2% performance penalty and the worry that something will go wrong up on the roof. Let alone the extra cost.

Thanks, I wonder if the bypass diodes favour a specific orientation, I cant see it being a big deal for my roof but perhaps on a larger install it might.

[Tay]

A SolarEdge system could be good there with those different aspects.

I think all things are on the table right now, although as I dont (at this time) have any other strings planned a dual MPPT should do the trick.

Now, if I consider a 3rd string on the North fence (after accidentally chopping some trees down in some kind of freak "OMG!! this chainsaw is out of control moment"), then entirely different angles perhaps might be enough to justify the optimiser/inverter route.

[nowty]

A SolarEdge system could be good there with those different aspects.

I'm not convinced. The two aspects are well catered for just with the two MPPTs, in the absence of shading.

By coincidence I was watching this video yesterday and it demonstrates conclusively IMO that the integral bypass diodes are usually enough and the merits of EnPhase and SolarEdge are overstated.

And personally although I have a small amount of shading on both my arrays I would not want a permanent 2% performance penalty and the worry that something will go wrong up on the roof. Let alone the extra cost.

Thanks, I wonder if the bypass diodes favour a specific orientation, I cant see it being a big deal for my roof but perhaps on a larger install it might.

Two equal length string but with differing aspects in parallel can be fed into a single MPPT, so 4 aspects can be dealt with a dual MPPT inverter.
https://camelot-forum.co.uk/phpBB3/view ... 9562#p9562

With regards bypass diodes, it depends, if your inverter can do a global peak scan every so often then the bypass diodes work, if yours doesn't, then they are worthless and the whole string is stuck at 0.5A. Also you need enough sunny panels (non shaded) to give enough voltage to be ahead of the min string MPPT spec. Your inverter may need a specific tweak in its setup for this to work.

If you have one or two difficult panels they can be dealt with TIGOs (single panel voltage optimisers) which work on even non global peak inverters.

But Tay's roof is so bad, its one of the few times I would say do solar edge and thats the best your going to get and less fecking about tying to get something cheaper to work.

[sharpener]

...after accidentally chopping some trees down in some kind of freak "OMG!! this chainsaw is out of control moment"

So it was you at Sycamore Gap!

[Tay]

...after accidentally chopping some trees down in some kind of freak "OMG!! this chainsaw is out of control moment"

So it was you at Sycamore Gap!

busted...

[sharpener]

Two equal length string but with differing aspects in parallel can be fed into a single MPPT, so 4 aspects can be dealt with a dual MPPT inverter.
https://camelot-forum.co.uk/phpBB3/view ... 9562#p9562

With regards bypass diodes, it depends, if your inverter can do a global peak scan every so often then the bypass diodes work, if yours doesn't, then they are worthless and the whole string is stuck at 0.5A. Also you need enough sunny panels (non shaded) to give enough voltage to be ahead of the min string MPPT spec. Your inverter may need a specific tweak in its setup for this to work.

If you have one or two difficult panels they can be dealt with TIGOs (single panel voltage optimisers) which work on even non global peak inverters.

But Tay's roof is so bad, its one of the few times I would say do solar edge and thats the best your going to get and less fecking about tying to get something cheaper to work.

Yes but without reading through the linked thread (which runs to 45 pages!) doesn't linking two arrays of different aspect means that either one or the other dominates at any given time and the other one goes to a suboptimal working point and contributes very little, whereas separate MPPTs would optimise both separately and so give you more in aggregate?

The problem with @Tay's roof is that it has so many small facets, but including the unused W-facing one they all seem to be clear of obstructions so can be combined into one W and one S-facing string. It looks from the inset pic in the planning tool as though there is scope for some E facing panels as well which would need a 3rd MPPT. Edit: or in line with the discussion here https://camelot-forum.co.uk/phpBB3/view ... 49&p=23276 and other linked threads you might get away with combining it with the W one.

Agree about global scan, there is a current Victron discussion thread bc their latest HF inverters have a different (and worse) algorithm whereas the older separate BlueSolar MPPTs are very good for this. I imagine that other high end European designed inverters like Fronius and SMA would have got this right as well.