Solar - real-life experience of investment vs return

ispookie666

@roadweary flat roof = planning permission
Even with that, I'd say it's worth it as long as you can get decent capacity on. 

1961Nick

2022 has been my best year for export - 4272kWh generated & just 89kWh exported - 98% self use.

Solarchaser

In terms of the cleaning, id say as long as you make sure to get pest protection around your panels, usually in the form off mesh between panels and roof, then you won't get pigeons nesting in them, so unlikely to get lichen issues and really the uk climate does a pretty good job at cleaning them.

The flat roof would probably be good for say 8 panels, and with 400w panels gets you to 3200w, you won't generate as much with them being flat, and especially not in winter when sun is lower,  but they should be alot cheaper install than your 3 story, so definitely worth considering imo.

I'm greedy with solar, so I'd be looking at filling your house roof and the flat roof, but if you were looking to dip your toe into solar, perhaps just the flat roof at the moment would be enough. 

Magnitio

Regarding your question about real-world experience, you've come to a forum where you will probably find the vast majority in favour of solar, but much more of a debate about batteries. Solar is now fairly mature, mostly reliable and should last for many years. The battery market is evolving fast and will certainly improve considerably in the next 10 years. I had solar and battery installed early this year and been pleased with it so far. Payback currently predicted to be between 5 and 8 years, but it will depend on future energy prices which are very unpredictable.

94JDH

roadweary said:

On a slight tangent, as we are a 3 storey building.....with stairs and very bad access all around for installation / cleaning....how do flat roofs stand for solar installs?  Here is the new office....perhaps a jot over 16m2.  Again, it is never overshadowed.  It is at the 2.5m max height avoiding planning permission issues.

Not sure if solar panels have to go at a certain angle, and if so, whether the additional height would be considered part of the structure for planning purposes?

I've had a install recently on two flat roof areas, one on the garage ( approx 7.3m x 4.5m) and one on the garden gym (approx 6.2m x 3.5m).
I went for an East-West system to maximize the number of panels ( 18 No. Total), if I'd gone for all South it would have been 9 No. Panels due to shading from adjacent panels.
I'm not getting a lot of generation in the Winter period but I'd factored this in by using batteries more in this period.
Also for me, the East-West will give me a longer spread of generation during the better months.

roadweary

Hmm.....I have the small flat roof....flat = not efficient...perhaps could use kits to create an angle, but then that might require planning permission.

When it comes to the main roof.....this angle looks more than 45 degrees (60?), which could be an issue again?

EricMears

roadweary said:  When it comes to the main roof.....this angle looks more than 45 degrees (60?), which could be an issue again?

Steep roof will probably generate less in midsummer but a lot more in midwinter (relative to a 'normal' roof).  What's the problem with that ?  Most normal rooves generate more than needed in summer but never enough in winter.

roadweary

EricMears said:

roadweary said:  When it comes to the main roof.....this angle looks more than 45 degrees (60?), which could be an issue again?

Steep roof will probably generate less in midsummer but a lot more in midwinter (relative to a 'normal' roof).  What's the problem with that ?  Most normal rooves generate more than needed in summer but never enough in winter.

Hi, no problem at all - I'm using the web and this forum to learn more.  I'd read about a 30-40 degree angle being optimal and that greater was an issue....and at a certain angle, perhaps not even possible for installation.  I also read that even 5 degrees from optimal can lead to a 10% reduction in efficiency...but that's the issue with the web.....there's good stuff, bad stuff, partially explained stuff etc.

Is there a resource you know of that shows the optimal angles at different seasons?

Thanks,
Andy

94JDH

roadweary said:

Hmm.....I have the small flat roof....flat = not efficient...perhaps could use kits to create an angle, but then that might require planning permission.

When it comes to the main roof.....this angle looks more than 45 degrees (60?), which could be an issue again?

I've used the Van Der Valk E-W flat roof system, it lifts it 10 degrees in both directions.

1961Nick

roadweary said:

EricMears said:

roadweary said:  When it comes to the main roof.....this angle looks more than 45 degrees (60?), which could be an issue again?

Steep roof will probably generate less in midsummer but a lot more in midwinter (relative to a 'normal' roof).  What's the problem with that ?  Most normal rooves generate more than needed in summer but never enough in winter.

Hi, no problem at all - I'm using the web and this forum to learn more.  I'd read about a 30-40 degree angle being optimal and that greater was an issue....and at a certain angle, perhaps not even possible for installation.  I also read that even 5 degrees from optimal can lead to a 10% reduction in efficiency...but that's the issue with the web.....there's good stuff, bad stuff, partially explained stuff etc.

Is there a resource you know of that shows the optimal angles at different seasons?

Thanks,
Andy

That's probably a reduction of 10% in 'peak' efficiency rather than overall efficiency.

An extra kWh in winter is often a lot more valuable than one on a summer's day when it likely to be exported. A steep roof could therefore result in more self use than one with the ideal pitch for maximum generation.