Opinions on this Job

[whinmoor]

Can anyone spot the schoolboy howler? It looks like the rows are equally spaced. I wonder what impact this would have on performance?

I'm not sure I'd be promoting this job on my website. It's especially ironic considering the client - aren't they supposed to be the fount of all wisdom in this industry?

Now we know why the SAP estimates have been on the low side if they are based on this!

How to make a 29.44kWp system with 8 panels? Maybe 128?

Gotta love the quotation with the emphasis on "quality":

Rajiv Bhatia, Director of Alternergy said, “We were proud to be selected as the supplier of choice for such a prestigious installation. With such exacting requirements on quality and delivery, Alternergy was one of very few companies that had the ability to deliver.”

BRE Offices Case Study - Alternergy

 

[Gavin A]

a nice case study in all that's wrong with the UK solar industry, and why it's so bad that the MCS guide has zero mention of bypass diodes or how to design to minimise shading impact within it.

 

[solarsavings]

And they think they put everyone else in the shade.

 

[Gavin A]

just stuck that on twitter, wonder if I'll get BRE asking for me to email them directly again rather than criticising them publicly.

Think I might have to print some copies out for the next MCS meeting I can actually make it to, and just pass them around to see who gets it.

 

[SibertSolar]

I'm actually gobsmacked, I wonder who was in charge of that project at BRE

 

[SibertSolar]

Is this a couple of years old maybe, this install?

 

[SibertSolar]

I thought I could smell RedTip in this story, and I can't believe Steve Pester would have erred with the row spacings, could the image be misleading somehow? Doesn't look it, I know....

http://www.redtip.co/BRE

 

[Gavin A]

I'm fairly sure their cocked it up completely, could have done that row spacing with landscape and got away with that shading, but in portrait it will turn a couple of percent losses over the year into maybe 8-10%.

This is why we have the situation where MCS, BRE etc treat all systems as if they all perform equally badly in shaded conditions no matter how they're designed.

I suppose there's a vague possibility that they did a detailed 3d modelling analysis and decided the extra shading was worth it to get extra panels in, but I suspect they chose the mounting system, got the company to do the system design and went with their design.

I wonder if BRE will recognise their system on twitter and attempt to defend the system design....

 

[SibertSolar]

I'll have a look for your tweet. Slim chance they calculated a benefit - bypass diodes! (As you mentioned). Baffled dot com

 

[Gavin A]

see we'd have done full 3d models and shading analysis on different options to work out the costs / benefits of each design.

but then we employ someone with a 3 year technical masters in solar PV from Spain, a level of solar PV qualification that doesn't even exist in the UK, where apparently all it takes is a 3 day course and that then qualifies you to go out and design and install any solar PV systems you want to, and MCS will certify you, and give you a get out clause by stating that it's impossible to calculate solar PV output accurately so whatever performance estimate they give is fine as long as they followed the correct procedure.

 

[whinmoor]

Glad I started a debate. The board had been a bit quiet recently.

Yes, I'm pretty certain the image is over 3 years old. It must be 128 x 230w panels to make a 29.44kWp system. REC 230s won the Photon test in 2011 so that may have inspired the module selection.

Gavin - Surely we really need to know either the spacings between rows or the time of year the photo was taken to gauge accurately the extent of the losses from this system? Photos can get distorted when manipulated for websites. If this is a winter shot, they may have knowingly accepted some shading for a couple of months to get more panels onto the limited roofspace and therefore higher overall yield. Saying that, landscape installation might have been smarter but the installers probably did (or tried to do) what Redtip advised them. [We should also remember that the industry was very young then.]

Saying that, your assessment that someone “cocked it up completely” is almost certainly true. The second “cock-up” is putting it on a website for the whole industry to see (and laugh at). Replacing the photo with one taken in summer with no shading or even on a cloudy day would be more sensible.

At least they had a handrail to keep H&S happy. :yes:

 

[Gavin A]

To make an accurate assessment you'd be right, but if you look at that photo, even from the height the photo's taken at, the first row of panels obscures the bottom of the 2nd row of panels, which I'd think would mean it will be at least March before it's out of shade completely at mid day, but will still be shaded mornings and evenings for much of the year.

Which might be ok if in landscape so only impacting on 1/3 of the system performance (assuming they'd use an inverter with full scan shading function), but in portrait that's going to have a pretty significant impact on the performance.

I've not analised this one, but did analysis on the difference between portrait and landscape for a 250kWp system on one of the old factory units with multiple small roof faces, casting shading on the bottom section of the next a while back, and the difference between portrait and landscape was around 30% losses vs 6%. (client still went with the other company, but not much accounting for the choices of idiots).

 

[whinmoor]

Gavin,

Check out this one (dated 8th May) we missed out on recently: https://www.facebook.com/greenyorkshire?fref=ts

Did you bid?

This window company has made a complete dog's dinner of it and is proudly displaying it on Facebook.

They used Sharp panels and clamped them on the short side. I spotted a few few other errors and omissions.

Very frustrating.

 

[Gavin A]

not just that, but they've not left any gaps between the panels, so come a hot summer day I'd expect thermal expansion will start popping those panels off the roof.

Don't think we quoted on them. Think I might have to start up a little how not to do it page on the website.

 

[SibertSolar]

Some feedback from a contact of mine in the BRE:

We got an extremely good deal on the hardware, which meant that it made sense to go for a higher-than-normal power density on the roof and accept some shading at low sun angles.
What this effectively means is that during the summer, we capitalise on the higher levels of irradiance and sacrifice some of the weaker, winter radiation.

If we had used normal spacing, with less inter-row shading at low sun angles, we would have had at least 3 fewer rows of modules due to space restrictions on the roof and the overall system size would have dropped by 5 - 7 kWp. Over the year, the PVSyst simulations show that the annual yield is better by about 4000kWh with the higher density solution, rather than fewer panels with less shading (even though the kWh/kWp will be lower). This worked financially for us because of the good deal we got at the time.

One of the photos on the websites you mention was taken at a low sun angle, and so shows some inter-row shading, which is not a good advert (I have asked for it to be removed), but from the above explanation, I hope you can see that the design is not as daft as it may look.