Limited roof space but wanting some PV

[cjw76]

Hi

I'm after some much-needed advice and thoughts from those with more than my zero experience as I'm a newbie in these parts. I've recently moved house and we'd really like to add some PV, but the roof is not the most friendly design - but is south facing, so I am thinking there could be some potential.

The roof has 3 dormer windows that interfere with the available space, so I think my only option is to have panels orientated landscape, but even then they would need to be relatively slim, because of the available space between the main ridge and where the ridge of the dormers join back to the roof. I've measured one of the slates to roughly estimate the dimensions of the space available.

So are there any experts in this forum who've faced a similar challenge and can advise on panels or fitters that might be able to help? ...or do I need to abandon the plan?

 

[Mrjmegson]

So I've bought (not yet installed) the Jinko solar tiger 400w panels, as they are 10cm narrower than most others at 103cm.

I checked with the MCS about the 20cm gap around the edges of the panels, and they say it's only a recommendation and not a law, so you don't need it, especially as no one has been able to give me a reason for it yet. The only issue I can come up with from having the panels to the bottom edge of the roof is that heavy rain could run straight off your panel and miss your gutters. You could use the stuff that you put in the gutter that allows water to flow in but pushes leaves over the edge. It would act as a bird guard at the same time.

You need to get up on your roof and have a measure up to know for sure.

I found one panel slimmer than these, but only 9mm, and they are out of stock everywhere, and over double the price. REC Solar, sorry, can't remember the exact name of that panel.

Have a general look round at panels, as there are various sizes. You might find you can use more lower power ones and get a bigger system on your roof by utilising more of your space. Higher watt just tends to be a bigger panel, as they all max out at around 22% efficiency.

Hope this helps.

 

[Mr Aargh]

Can you fit panels with optimisers onto the eadt/west facing bouts of the dormers? They would have to have optimisers.

You can get 8 1m wide panels at the top. On the lower porch roof 4 more perhaps, but as you say mucking up the function of the guttering. Pigeon proofing is necessary throughout BTW.

People: could we all rally round and find a Web link to some panels less than 1m width for cjw?

 

[michael8554]

The recommendation for panels ending 20cm before the edge of the roof is to reduce the chances of wind blowing the panels off the roof the next time Mr Fish gets the weather report wrong.......

 

[Geoff1946]

The recommendation for panels ending 20cm before the edge of the roof is to reduce the chances of wind blowing the panels off the roof the next time Mr Fish gets the weather report wrong.......

Or, I suspect the risk of lifting the whole roof structure. When my roof was surveyed there was concern about, "wind uplift", and that there are no straps tying the roof timbers to the walls. I can visualise that overhanging panels would give some resistance to wind from the right direction.

 

[Mrjmegson]

The recommendation for panels ending 20cm before the edge of the roof is to reduce the chances of wind blowing the panels off the roof the next time Mr Fish gets the weather report wrong.......

Ha ha ha, love that reference.

 

[Mrjmegson]

Well the MCS themselves couldn't give me an answer when I directly asked them about the 20cm, other than if it was against a neighbours boarder, it would require access to be work on should any issues arise.

 

[Mrjmegson]

Or, I suspect the risk of lifting the whole roof structure. When my roof was surveyed there was concern about, "wind uplift", and that there are no straps tying the roof timbers to the walls. I can visualise that overhanging panels would give some resistance to wind from the right direction.

Cowboy builders cutting costs. Sounds great.

 

[binky]

Well the MCS themselves couldn't give me an answer when I directly asked them about the 20cm, other than if it was against a neighbours boarder, it would require access to be work on should any issues arise.

It's a bit of a myth, you can fit panels right to edges of roof or even overhanging if you have sufficient roof hooks and suitable frame. What you have to be careful of is disturbing cement along edges and ridge lines and preventing wind getting under edges of roof materials. That generally makes it untenable. It doesn't come recommended. Incidentally the wind does more damage by creating a vacuum as it blows over the roof edges, another reason for not putting panels close to edges, plus the gap allows some work space.

 

[Mr Aargh]

If the panels are fixed correctly to your roof, the panels will last longer than the tiles. Shop around - there are panels less than a meter width and an installer can help with greater sources of stock, potentially.

 

[Mr Aargh]

I would add that the viability or competitiveness of an installer's quote is often determined simply by which panels they have in stock and what dimensions: if they only have a large stock of all black 1.12 meter widths, it doesn't matter how good they are, they won't be able to match a quote from someone whose panels basically are of a different dimension but fit properly on your roof.

 

[Geoff1946]

Cowboy builders cutting costs. Sounds great.

No, not really. My bungalow was built in the 1950s. I don't think roofs were tied down in those days, but the timbers are massive by present standards and the structure carries concrete tiles. I have little fear of even Blackpool's gales shifting it. I've also added half a ton (guess) of solar panels.

 

[binky]

No, not really. My bungalow was built in the 1950s. I don't think roofs were tied down in those days, but the timbers are massive by present standards and the structure carries concrete tiles. I have little fear of even Blackpool's gales shifting it. I've also added half a ton (guess) of solar panels.

4kw is roughly half a ton

 

[Mrjmegson]

No, not really. My bungalow was built in the 1950s. I don't think roofs were tied down in those days, but the timbers are massive by present standards and the structure carries concrete tiles. I have little fear of even Blackpool's gales shifting it. I've also added half a ton (guess) of solar panels.

Bloody hell, if it stands up to the weather in Blackpool, it's definitely fine.

 

[Mrjmegson]

4kw is roughly half a ton

Is that including all the mounting materials?

 

[Mrjmegson]

It's a bit of a myth, you can fit panels right to edges of roof or even overhanging if you have sufficient roof hooks and suitable frame. What you have to be careful of is disturbing cement along edges and ridge lines and preventing wind getting under edges of roof materials. That generally makes it untenable. It doesn't come recommended. Incidentally the wind does more damage by creating a vacuum as it blows over the roof edges, another reason for not putting panels close to edges, plus the gap allows some work space.

Thanks Binky, that was a really comprehensive answer, I really appreciate it.


Interesting about the vacuum effect of the wind.

 

[Geoff1946]

Bloody hell, if it stands up to the weather in Blackpool, it's definitely fine.

Ah, you've been here in winter!

 

[binky]

Is that including all the mounting materials?

Yes

 

[binky]

Interesting about the vacuum effect of the wind.

Works in a similar way to aeroplane wings, but sucking is worse than blowing . I'm going to stop posting and put the bottle of rum down.

 

[Mrjmegson]

Ah, you've been here in winter!

My Mum lives in St Anne's, so I've spent many a fun walk trying to battle the winds. Lol