1.
Anon
at
13:12 05/01/2011
The effects of shading cannot be under estimated, it has a dramatic effect and should be avoided.
Any professional installer will have experience and training on this issue.
This is one very important issue that potential client should be aware of.
2.
Anon
at
13:31 05/01/2011
It is correct that Shading does dramatically affect a 1 or 2 string array however there are ways around this which is an inverter per panel (ENECSY) this means only the panel shaded will be effected and NOT the whole array.
3.
Jamie Geddes
at
14:02 05/01/2011
Shading is a very important issue. Generally as an installer we would ensure shading is kept to a minimum and advise our customer what difference it would make if there is any shading on the array.
We always use string inverters and modules with bypass diodes which minimises the overall reduction in generation due to shading. Although the idea of microinverters is interesting I am not aware of any in use in the UK. I am aware of some use in North America but they are not G83 approved and so cannot be used in the UK. In addition I would expect a significant price increase from using individual microinverters and increased failure rate.
The
4.
Jamie Geddes
at
14:09 05/01/2011
I have just learnt the Enecsys micro inverters are G83 approved, but as I say I don't know of any installers using them in the UK at present.
5.
Anon
at
15:39 05/01/2011
The effects of shading cannot be under estimated, it has a dramatic effect and should be avoided.
Any professional installer will have experience and training on this issue.
This is one very important issue that potential client should be aware of.
6.
Derrick McCormick
at
19:26 05/01/2011
We would always advise against installing an array that is subject to shading but there are Panel MPP trackers that can minimise the effect. they are not cheap but if you spread the cost over the entire installation it can make them viable.If there are many panels that are subject to shading it is not viable. Any reputable installer will say no and we would advise installing solar thermal if the client wants to install a renewable technology.
7.
Paul Hutchens
at
21:06 05/01/2011
Shading - particularly hard shading - is the biggest problem for a solar PV system. In fact the more intense the radiation the more the shading is an issue. Using multiple inverters, multiple strings and MPP trackers will help to isolate the shaded part - particularly if only part of the array is shaded - but it is best to avoid shading at all if possible.
Paul Hutchens, Eco2Solar.
8.
Anon
at
12:34 06/01/2011
Hi. Shading can double the FIT payback time! However, the system will still work So as long as this is all made crystal clear to the potential customer - occasionally some will wish to proceed nonetheless, especially if the shading is not too severe or its duration too long (as a proportion of the day). If serious shade - occasionally suggestion towards solar thermal (which is far more forgiving of shade) can be the right way. I think the important thing is to not mislead people, better to paint worst case scenario - then let them decide.
Adi
9.
Steph Harby
at
16:47 07/01/2011
Answering each question in turn:
What amount of shading makes an installation not worth while? It depends on the driver for your system. This could be financial, environmental, planning or marketing. With the FIT I would estimate that 50% shading makes it uneconomic.
Is it worth having a smaller system to avoid shading issues? This is answered above.
Are there any solutions to a PV system that is part shaded during certain times of the day? Others have quoted Enecsys which is one option of many that are now getting G83 approval. We are working with a manufacturer that does power conditioning at the module level whilst keeping the inverter at the string/array level. Thin film systems are generally more tolerant of shading, but of course have a lower output per m2.
Can shading damage or reduce the longevity of a PV system? Yes - it is possible that shading across part of a string can damage modules if the diodes fail.
Carl Benfield, Prescient Power Ltd
10.
Paul Chandler
at
12:15 10/01/2011
I agree with the above. Shading can have a SIGNIFICANT impact (and potentially damage panels). Solar hot water is generally better suited to sites with partial shading as it will not get damaged and it is fairly cheap to increase the collect area to compensate for shading.
Paul, T4 Sustainability Ltd
11.
Jon Walker
at
18:16 11/01/2011
Just to let Jamie Geddes that at least one UK installer is using ENECSY Micro inverters - us! We think they're great and offer them at additional cost when patchy shading is an issue, e.g. chimney shading, dormer window shading etc.
Jon at 1 World Solar in Bristol
12.
Anon
at
22:44 28/04/2011
I've been told the icro inverters are not MCS and so an array using them won't qualify for FiTs?
