Buying Advice

[rob75]

Hi,

I'm looking at a Solar PV install. My roof is south facing and I have enough room for a 2kw system.

The installer has given me several manaufacturers to choose from:

Sanyo HIT H Series 250W
Schueco 250W

My head says go with one of the above two - any feedback or suggestions regarding the above?

Other options:

HJ Solar
(£150 less than Sanyo)

Kyrocera
Romag
(£570 less than Sanyo)

Hyundai
Sharp
(£1050 less than the Sanyo)

If I have the budget for the Sanyo or Schueco am I better investing the £1050 prce difference in the better panel rather than saving on a cheaper panel such as Hyundai or Sharp?

Any feedback or suggestions very much welcome.

Thanks.

[bxman]

SunPower E20 Solar Panel

Rather wish I had Known about these when I had my install last November.

Someone on here has them and they had impressive figures which caused me to search for more information 330-340 watts per panel
from 96 cells at better than 20% efficiency.

[M]

Rob, the hybrid sanyo's should be smaller, allowing you to install more watts per m2.

Is the 2kWp figure for the normal or hybrid panels. The additional cost of the sanyo's may be worthwhile in the long run if they allow you to install a larger system overall. It's really a number's game.

Do you have any more data?

Mart.

[rob75]

Thanks for the replies.

My position is 160 S/SE with a 40 degree pitch roof.

Is there any other data I should post.

The Sanyo's are hybrid, but I am sorely tempted by the Schueco.

Thanks,

[JohnS]

As Mart says there is a difference in size.  Sanyos are 861*1610mm and the Hyundai are 983*1645mm.

You might get an extra panel in using the Sanyos.

Other things being equal, eg the roof might be better suited to a 2*4 layout rather than a 3*3 with a 7 panel layout looking naff, I would go for the cheaper ones but if space is a constraint, go for Sanyos.

I had space constraints.

John

[rob75]

Space is definitely a consideration because I am end of terrace and the south facing roof is not full-size.

Are my orientation and pitch ok though. Iguess 160 degreess is -20 optimunal.

[brackwell]

Rob ,your orientation is fine.

Basically you need to get the max kwp that you can get on the roof and therefore its kw/m2 that you need to be interested in. A  250w panel say will produce the same as the next 250w panel but there could be a differece in size.
You need to ask the supplier what is the max you can get on your roof. Sure it will be more expensive for the panels but that is only half the total cost-the rest will stay the same.

Ken

[langstroth3]

..agree with previous comments ref Sanyo or other in terms of getting max kWp for the space available. I've not read very good things about the build quality of some of the Sharp's, but I'm no expert, but you might want to look into that.

Don't forget the rest of the system - the panels are only one part of it.

Also consider:
Inverter efficiency / type
Length of DC cable run's / placing of inverter (loft vs some other ventilated, less dusty hot place such as garage).
Reputation / references for selected installer
Type of fixing used to attach panels to the roof

Also:
Access to inverter if you want to do any monitoring (or use of remote access)

[defiler]

Bear in mind that if you *can't* fit in extra panels by going down the Sanyo / Sunpower route then go with cheaper panels and use the extra space - it'll work out more cost-effective.

[M]

Would a Which checklist be useful, given the title of this thread.

Wifey sent it to me today, don't normally get pressies, should I be grateful, or suspicious?

http://www.which.co.uk/documents/pdf/solar-pv-checklist-pdf-269629.pdf?cmp=W0112_p7_solar

Mart.

[bath_ed]

Hi all, I have another question about buying so I hope you don't mind me adding it here.

I've had a quote from GD Electrical & Solar of Minehead to install on the asbestos cement sheet roof of my British Iron and Steel Federation (BISF) house in Bath. The house is a 3-bedroom semi with internal dimensions of 6.3 x 6.3m (ie not counting wall thickness or eaves overhang). The roof is a simple pitched roof (not sure of the technical term) with only one ridge, the construction is a little unusual in that the asbestos sheeting is attached directly to steel purlins with no rafters or any other timber in the roof structure, and it has an angle of approx. 20 degrees (fairly shallow), facing south west.

They have quoted me £6 667.50 for a 3kWp system of:-

12x Suntech 250 panels
Schueco PV Light 2 mounting system - to suit requirements
Power One 3000 invertor
2x ACEL AC isolators
2x ACEL DC isolators
1x total generation meter
DC cable to suit requirements
MCB 16a to fit distribution board
AC cable to suit requirements

Their SAP calculation is a yield of 2465 kWh per year.

I was wondering what users thought of this. Another installer quoted a lot more and warned of the evils of kit systems.

[supremetwo]

£2.22/Wp looks a good price to me, but what has been said about roof loading calculations?

http://www.navitron.org.uk/forum/index.php/topic,15042.msg168473.html#msg168473

The building regulations department of your local authority will want an engineering report.

All PV systems are made up of a kit of parts so the other quoter is talking what comes from his rear end.

[JohnS]

bath-ed

One of the links on the replies to your earlier posts gave details of a company which refurbished BISF properties.  In the section on roofs, it said that they used lightweight materials becasue the original roofing was also light and the structure would not support heavier weights.

Building regs seem to allow a 15% addition to roof loading without a problem.  Above needs structural calcs.

However it is not clear how the 15% is calculated.  Is it

a) panel area to roof area
b) panel area to area of roof same width and ridge to eaves
c) panel area to 'shadowed' area of the roof

b) is the most logical. If there is only one row of panels, there is less loading than two rows.

In my case, I came in just below 15% on a clay tile roof.

Hope this helps.

John

[bath_ed]

£2.22/Wp looks a good price to me, but what has been said about roof loading calculations?

http://www.navitron.org.uk/forum/index.php/topic,15042.msg168473.html#msg168473

The building regulations department of your local authority will want an engineering report.

All PV systems are made up of a kit of parts so the other quoter is talking what comes from his rear end.

Thanks for your advice. I suspected as much about the kits, his point was that the number and wattage of the panels in the kits installed was not necessarily well matched to the inverter used. I can see how that could be a factor, but was dubious of whether it could justify the higher price for a 'tailor made' system (especially as it was 2.5kWp rather than the above 3kWp).

I have some concerns about installing on the asbestos roof apart from the loading questions. My main one is that I believe asbestos cement sheets are brittle/fragile. If one was broken accidentally in the installation, it wouldn't be like breaking a tile or slate that could be easily replaced. How could I ensure I was covered against that possibility?

[bath_ed]

bath-ed

One of the links on the replies to your earlier posts gave details of a company which refurbished BISF properties.  In the section on roofs, it said that they used lightweight materials becasue the original roofing was also light and the structure would not support heavier weights.

Building regs seem to allow a 15% addition to roof loading without a problem.  Above needs structural calcs.

However it is not clear how the 15% is calculated.  Is it

a) panel area to roof area
b) panel area to area of roof same width and ridge to eaves
c) panel area to 'shadowed' area of the roof

b) is the most logical. If there is only one row of panels, there is less loading than two rows.

In my case, I came in just below 15% on a clay tile roof.

Hope this helps.

John

Were you talking of http://bisfhouse.com/bisf-roof-with-a-view ? That BISF house site is pretty useful, though it is not written by an engineer (as far as I know) but by someone who owns several BISF houses. He says: "The roof structure itself could indeed hold the weight of traditional roofing tiles, however the combined weight of such tiles along with all other materials used in the entire build would have placed far too much excess weight onto the steel stanchions (legs) of the house. Combined with the need for speed of installation using unskilled labour, asbestos based corrugated sheeting was the obvious choice."

For the roof loading calculations, would one count just the roof covering itself (ie the asbestos sheets) or the entire structure (asbestos sheets plus steel purlins plus steel trusses)? The weight of the panels would almost certainly be more than 15% of just the asbestos, but probably not 15% of the weight of the asbestos + steel.

Also, would I expect the installing company provide an engineering report to the council, or would I be responsible for arranging/doing that myself?