Shading : yes, it does make a difference !

[HPSauce]

Thanks series, pages now working in IE.
That's a great record of your findings.

I have a similar equipment to yours but the shading is from trees 17 to 30 metres away. Should be fine for 6 months during the summer. I hope.

 

[moggy1968]

I have now been able to see the page in full. It is interesting stuff. as I suggested above a single string single inverter set up would make an interesting comparison. would love to see a direct comparrison, particularly to see what effect is caused by cloud shade on an otherwise unshaded system.
I have never used microinverters but have an installation coming up on my parents roof which I would like to use them for as a bit of an experiment.
like the software, what is it? presume it's Enecys own, is it bluetooth?

 

[HPSauce]

The monitoring is done by logging on to the Enecsys website. The micro-inverters talk to the Enecsys gateway box using Zigbee (a more recent system than bluetooth). The gateway box is then connected to your router.

 

[SolarCity]

It is Enecsys' own monitoring system - excellent stuff and one of the big draws for their product in my opinion.

The comparison with a string inverter would be great but this kind of data is difficult to get hold of. The area behind your chimney is particularly interesting as it does throw up an interesting question that is one of the most crucial in system design - what kind of difference in yield can we expect between micro-inverters, single MPPT inverters, dual MPPT inverters and simply leaving the area without panels.

From my experience of designing in PV Sol Expert, I normally find that leaving the area clear of panels is the better option. However, even though I trust the accuracy of the software, solid real world data is absolutely invaluable.

 

[scottliv]

Ian, have you considered lowering the chimney height. I have done this to mine as it was similar to yours - right in front of the panel. Unfortunately my neighbors house shades one panel in late afternoon. They won't however, let me put a flat roof on their house! My installer wired the system up in one good and one bad string to an SMA 4000TL. I can see the effect though in the afternoon. It has only been running for 10 days but should not be a problem in the summer with a higher sun.

 

[series530]

Lowering the chimney height ... the wrecking ball comes tomorrow!

Seriously, I doubt that the chimney will be a huge issue during the summer months because the sun will be higher. Similarly, the same applies with regard to the neighbour's chimney and aerial.

My attitude is that that everything is a compromise and even the panels behind the chimney will harvest well beyond their cost during the life of the FIT (I always take a longer term view) so it's better to win on aesthetics (ie. keep the chimney) than to pull it down just to get a few more KWh. Anyway, it would probably cost more to knock the chimney down than the compromise in harvest during the peak months by leaving it intact.

What I wanted to illustrate to anybody who is interested is the compromise that shading of any description brings (irrespective of time of year) and the fact that bypass diodes are not necessarily the holy grail of shade mitigation.

 

[scottliv]

Agreed a good view to take. The long term one. I managed to get my scaffold up early to do the chimney. It needed remedial work anyway and was not of the same scale as yours. The stumpy version looks good though.

 

[jetski]

View attachment 8823.

Hi great write up, my system has been going from the second week in July as you can see my system consists of 8 panels on the South and 12 on the west roof my shading comes in the form of a tree quite close to my bungalow which brings panels 3,4,5 down on the south roof and to some extent a few on the west side. July and August probably wasn't as good as it could have been but October was quite exceptional, on the whole quite happy so far

 

[series530]

Hi jetski,

I wasn't able to open your attachment.

 

[LiftMan]

My first post, customer not installer.
I have been planning an installation for a couple of months and due to multi-roof bungalow, I could see that shading was to be an issue. I was interested in micro-inverters and was desparate for useful information like this. Many thanks Series530, you are now my hero.
Unfortunately the enecsys deliveries leave a lot to be desired and the governments wonderful planning has put paid to my hopes. However, my installer is most helpfull and we are now installing a standard two string arangement with Tigo Maximizers. Hopefully this will help with some of the issues.
I would not insult members of this forum, but you must remember that from a client point of view, it is extremely difficult to assess who is actually good or bad. In most cases, advise from a specialist, is taken at face value, and the customer is never the wiser. I may be oversensitive about shading but I have had several quotes and not one has highlighted it as being a problem, quite the contrary. It was pretty much dismissed.
I was rather disapointed that Series work was dismissed by some members because a control was not in place to compare with standard string arrangements. When you can provide such detail from an inverter readout I am sure many customers, and members alike will be interested in the results.
As an invester, and someone interested in green issues, it is my opinion that the government should wake up and realise that a return of £5k after 25 years for a £12k investment is ridiculous particularly when you are out of pocket for the first 18 years.
That's it I'm done. I should just like to thank all members of this forum as it has been facinating and a privilege to eavesdrop into conversations of people so interested and devoted to improvement of their industry. I am also truly sorry for the hardship and turmoil you have and will have to endure as a result of the illconceived changes to the Fit Scheme.

 

[series530]

A good first post Liftman and thank your for the postive comments regarding my post.

Understandably, from the supplier perspective, there is some resistance to micro inversion : thrust upon a customer base who are very price sensitive by suppliers who fear the cost of supporting an inverter per panel and from a company who have a less than perfect customer focussed approach, I can understand the reluctance to embrace the product.

We were offered Tigo by one string advocating supplier. I see no issue with them and, given the Enecsys and Government road blocks I think that, if you have shade issues, anything to mitigate this is a very worth while investment - especially if you view the investment as a long term one.

I am heartened by the responses to my observations for the most part. Yes, there was some hostility but, in the main, people were very open. I wasn't trying to push micro inverters in any way. All I wanted to to do was to provide some useful information that would allow consumers and installers to make an informed judgement. I am not the National Physical Laboratory so my controlled experiments are limited. I just wanted to be fair and objective. I think (and hope) that most people believed that I was.

 

[moggy1968]

I think some of the comments above may relate to my posting and appologise if it caused some discomfort or even offence, certainly not my intention.
What was my intention was to highlight the caution that should be attached to data and the interpretation of data when limited controls are in place. It's important not to confuse obervation with controlled and checkable scientific data.
However, I actually also found the information very interesting, to the point that I considered installing a microinverter system on my parents property!!
I think as an observational report your input had a lot to recommend it and certainly made me consider the effects of shading more carefully than maybe I did before, although I have, as I pointed out, always advised of potential shading issues, and even put people off having an installation due to excessive shading.
with regards to choosing an installer, recommendation is always a good guide, but even then be careful as some installers offer very large referal bonuses. A couple of things I would personally look out for, and some may not agree of course it's just my observation.
1. Does the firm subcontract the work out or are they directly responsible for their workforce and the work they do.
2. do they work in a related industry? 2 reasons for this, one is that when all this shakes out a lot of firms who have put all their eggs in the solar basket won't be there anymore and their warranty will be useless and also it may demonstrate competence in the associated parts of the installation (if they are an electrical firm for example)
3. Do they have previous customers you could talk to? These won't be on a referal bonus and so have an independant viewpoint, hopefully!
4. did someone else speak highly of them, without it being a direct referal.
5. When you ring them, who do you speak to? If it's the boss that answers the phone, then if you have a problem then hopefully it will also be the boss you speak to rather then being passed from pillar to post.
6. get several quotes, and don't necesarilly go for the cheapest, Your investing a lot of money so go for the one who gave you the best advice (in your opinion) and seemed the most honest, demonstrated a good knowledge and who you just liked the best!!
7. Avoid the firm that uses hard sales tactics!

 

[GreggElectrical]

The effect of shading after the shadow has disappeared is bothering me. Could it be due to the increased heat generated in the shaded panels? Once the shadow has gone the panel would still generate less than the cooler unshaded panels. It would be interesting to see how long it take (if ever) before the panel recovers. If this is indeed the cause then the effect would be worse in summer when ambient temperature is higher.

 

[series530]

I think some of the comments above may relate to my posting and appologise if it caused some discomfort or even offence, certainly not my intention.
What was my intention was to highlight the caution that should be attached to data and the interpretation of data when limited controls are in place. It's important not to confuse obervation with controlled and checkable scientific data.
However, I actually also found the information very interesting, to the point that I considered installing a microinverter system on my parents property!!
I think as an observational report your input had a lot to recommend it and certainly made me consider the effects of shading more carefully than maybe I did before, although I have, as I pointed out, always advised of potential shading issues, and even put people off having an installation due to excessive shading.
with regards to choosing an installer, recommendation is always a good guide, but even then be careful as some installers offer very large referal bonuses. A couple of things I would personally look out for, and some may not agree of course it's just my observation.
1. Does the firm subcontract the work out or are they directly responsible for their workforce and the work they do.
2. do they work in a related industry? 2 reasons for this, one is that when all this shakes out a lot of firms who have put all their eggs in the solar basket won't be there anymore and their warranty will be useless and also it may demonstrate competence in the associated parts of the installation (if they are an electrical firm for example)
3. Do they have previous customers you could talk to? These won't be on a referal bonus and so have an independant viewpoint, hopefully!
4. did someone else speak highly of them, without it being a direct referal.
5. When you ring them, who do you speak to? If it's the boss that answers the phone, then if you have a problem then hopefully it will also be the boss you speak to rather then being passed from pillar to post.
6. get several quotes, and don't necesarilly go for the cheapest, Your investing a lot of money so go for the one who gave you the best advice (in your opinion) and seemed the most honest, demonstrated a good knowledge and who you just liked the best!!
7. Avoid the firm that uses hard sales tactics!

In the case of my data, it is, indeed, observational. It's very difficult to do a controlled experiment unless pockets are deep and an environment is synthesised in order to allow a fair comparison of a number of different system installations in real time and at the same time. The very nature of one inverter technology against another makes it difficult to compare and contrast technologies aside from at the final harvest level (which, to be fair, is all that many people want). It would be pretty easy to build a number of systems on a ground mount in a field but it's actually quite difficult to simulate the effects of shading completely fairly in a field situation. Plus, an open field, no matter how you describe it, is not the same as a typical residential urban environment that most consumers would live within. So, we do what we can and offer the observations that we can. I'm all for healthy debate and, if people read these posts and save themselves just twenty quid from the advice that is on offer, it's worth it!!!

Considering the list of points at the end of the quotation, I find them all extremely valid: In the case of my chosen installer (after much deliberation), they have their own installers, they specialise in anything with a green/renewable bias (but solar is their main area), they gave me two customers to talk to and I talked to both at length. Being newish (which was my biggest worry), there weren't other people who I could approach. They did, however, get many good reviews on an independent review site. They have office staff but the boss was always there and accessible either directly or within a short while. They were the dearest (by quite a long way)!. The boss came out, did the survey and answered all of my questions. The staff at the office prepared the shading analysis and quote and handled all of the logistics.

I would also add that I think it's a good idea to go with a company who offer an independent insurance backed warranty. I figured that plenty of companies would go south once the FIT reduces or simply because they weren't successful enough. The warranty is then useless unless it is externally underwritten. Needless to say, ours has a 10 year independent warranty.