3.9kW system Essex, completed 30 Nov 2011

[don0301]

hello all

just joined, from a recommendation from a member. I thought some pictures of my installation would be an ideal way to say hello 

[Cornish Dragon]

Yes indeed there don0301.....
very nicely done and very neat..
Also with a long handled cloth I think they
are all cleanable occasionally.....
Welcome to the forum
Are you planning any other renewables
it is addictive !
CU
CD

[don0301]

haha, yeah the velux windows will come in handy 

i was very pleased with the installers, local company, on a neighbours recommendation.

I'm not sure what else i can do, its a modern house and limited garden space.

i will enjoy reading and learning on here tho

thanks for the comments.

[M]

Welcome Don, nice to see you made it.

Are you still wondering about those outside edge panels?

Mart.

[don0301]

yeah, i was hoping some knowledgeable people here could (hopefully) put my mind at rest regarding the panels proximity to the roof edges.

i have read some conflicting information elsewhere.

i did wonder about matching a 3.5kW inverter with 3.9kW panels too, if anyone would like to comment on that  

to be fair to the installers, the install was quoted just before the announcement last year, installation was just before the 12 December deadline, and they did have difficulty sourcing components.

i have a fronius IG Plus 35V inverter, 20x195W ZNShine ZX155-195MS panels, south facing roof, 49 degree tilt, Essex Lat 51.9 degrees.

hope thats all the information needed.

thanks in advance for any helpful information.

[Richard Owen]

yeah, i was hoping some knowledgeable people here could (hopefully) put my mind at rest regarding the panels proximity to the roof edges.

What exactly, is your concern?

Unless you have very high wind loading coming in at an acute angle of shear I can't see a particular problem.

As long as the roof brackets are in-board of the verge ladder I can't see you are going to get any peculiar drooping of the verge boards.

i did wonder about matching a 3.5kW inverter with 3.9kW panels too, if anyone would like to comment on that  

It will give you slightly better performance in sub-maximal conditions and in maximal conditions you'll throw some power away.

Swings and roundabouts.

[BruceB]

Agree with the above.  It is generally considered poor practice to put panels too close to the edge (say 400mm), because the wind loadings are significantly higher.  But it is not a problem if the installer does it properly with enough roof anchors near the ends of the rails not spaced too far apart.  There are calculations/guides that take account of where you are in the country, height of roof and exposure to winds.  The installer then matches that to the manufacturer's data on the rail system being used and the roof construction.  I have gone right to the edge on my own property just to maximise area of panels on an outbuilding.

I was expecting to hear of solar panels installed in a rush flying off roofs in the storms before Christmas.  But the only one I remember was an array under construction at a school.  I think the design figures are pretty conservative and you would be unlucky to have a problem unless your house is very exposed.

Another reason to keep inverter output below 3.68kW (16A equivalent|) is that you would have needed prior permission from the DNO to install it rather than informing them afterwards.  Difficult in the run up to 12 Dec.

Regards
Bruce

[don0301]

thanks for the answers

my concern was reading comments I've read elsewhere about there should be a gap anywhere between 200-600mm from the edge of a roof (depending on comment I've read)

regarding the storms in December, i had no problems, no noises at all from the roof. *touch wood*

I did check Building Regs, and as I understand it, the only "rule" is regarding ridge tiles.

regarding the inverter/panel match i was just wondering if it was an "optimal" match for my location/circumstances.

just seemed a little wierd to me when i found out the inverter was rated lower than the panels.

[BruceB]

The gap to the edge requirement is a rule of thumb.  You can design it out.

There is no applicable building regs rule as far as I am aware.  The 'not above the ridge tile' rule is a planning permitted development one.

Your panels very, very rarely push out full power.  Design is a compromise.  Bigger inverter to take the full possible power costs more money.  Bigger inverter does not work quite as efficiently as smaller inverter in marginal conditions.  Bigger inverter can push you into next higher FIT band so lose money (not in your case).  10% to 20% over-panelling in this country for the size of system you have is, in my opinion, good.

Regards
Bruce

[don0301]

ah, thanks for the correction, that was what i meant about the ridge tile.

and thanks for the reply again.