Solar PV...Still worth it?

silvercar

Solar panel guy called today.

Lots of measurements. Seems I can have 3kwp on the house, but could have 4kwp on the summer house and shed roofs. This seems a better option as they would not spoil the look of the house, though I am slightly worried that the solar panels would last longer than the shed!

There is already power to the summer house and this could be used to take the generated electric back towards the house.

Detailed quote coming in the post, but he's quoting about 8,900 for British made (Sharp) PVs and 8,000 for Chinese panels for the 4kwp system.

His calculations showed that I would save (FiTs+feed-in+ electric saving at 10p per KwH) around £800 a year.

Unpressurised chat, I felt comfortable that he answered my questions.

See what the quote details.

EricMears

silvercar wrote: »

though I am slightly worried that the solar panels would last longer than the shed!

Unlss it's a particularly sturdy garden shed, I'd be seriously worried whether it would take the weight !

However, with a bit of reinforcing first, it should be OK and ought then to be good for next 25 years.

mardycow

well my system was installed end of October 2011 and i have now generated just over 1000 kwh, 3.99 kw system in the midlands

WestonDave

Hope this is an OK place to ask this but getting confused with solar quotes. If there is a better place (and I'm concious that this board gets cluttered with new threads so didn't start another!) please point me in the right direction.

Have a L shaped roof near Bristol which gives us south east and south west aspects roughly evenly split.

Quotes so far are around £6k for a 3kwp system based on 12 Suntech panels, unnamed invertor, or £8k for a 3.6kwp system based on 14 EMMVEE 260w panels with I think Danfoss invertor. It might be possible to tweak the first one to get 14 panels on - our roof is a nightmare to survey as the sides they need to look at are on the down slope side which makes getting a view from above hard.

Both installers have decent reviews on YouGen and are reasonable sized companies - neither direct recommendations as we don't know anyone who has had it done.

The cynic in me thinks pay peanuts get monkeys so is there any obvious reason why the cheaper quote is a bad idea. The guy quoting for the cheaper ones appeared thorough and has pointed up a potential issue with the roof that the other didn't spot (6m long unsupported purlin which might or might not be strong enough for extra weight!). The more expensive quote came with lower pay back - both quoted around £800 (including FIT's, export and offset) so the EMMVEE panels are on a more conservative basis.

Any thoughts (and anyone think of any companies in the Bristol area worth getting to quote for a third/final option).

Thanks

EricMears

WestonDave wrote: »

Hope this is an OK place to ask this but getting confused . . . .

Any thoughts (and anyone think of any companies in the Bristol area worth getting to quote for a third/final option).

Thanks

I'd say it was an ideal place to be asking. We've got several regular posters from the SW (but I'm not of course one of them) so somebody may well PM you with a recommendation.

Really no reason to assume that 'more expensive must be better' ! It might just be the difference between a small local firm where proprietor does his own installations and sales visits and a huge national company with a network of salesmen to pay. But always worth getting several quotes and carefully considering all the points made by respective 'salesmen'. It can be difficult to compare alternative quotes unless you've worked out for yourself which of the offers makes most sense and then asked the other firms to tailor their quote to match.

With two rooves pointing in different directions, it's going to be important that you get an inverter capable of handling the two sets of panels independently. If not, the ones in brightest sunshine will be held back by the other set.

EricMears

WestonDave wrote: »

our roof is a nightmare to survey as the sides they need to look at are on the down slope side which makes getting a view from above hard.

Have you tried looking at your roof from above courtesy of Google maps ? http://maps.google.co.uk Select 'satellite view' and you'll usually get a reasonable aerial photo.

grahamc2003

Weston - Just to restate what Eric said - it's critical to get a twin mppt inverter (or a set of microinverters, or a hybrid system like solar edge). My installer didn't like the last two options since he thought having several inverters in the harsh outside environment just meant there were more things to go wrong - in the end, i agreed with him).

I also have an se and ew roof (I only have panels on the sw one). You have to be aware that the sw roof will cause a shadow on the se roof - mainly in the winter when the sun is low. With most inverters (even twin mppt) a little shading causes a big drop in power - I've read 10% shading leads to 90% power drop, and my experience backs that up. So as well as a twin mppt inverter, you could make sure that the inverter software is designed for shading (when the effect of shading is much less). I'd certainly make sure you know exactly the model of inverter is in each quote, and that it has twin trackers and, preferably, newly designed software which handles shading.

btw, your roof roof shading isn't a show stopper - just make sure you have no other shading between say 11 and 4 each day when you'll get the bulk of your generation.

WestonDave

Hi Eric - yes we've done that. Its mostly OK but whilst the elevation angle on both arms of the roof is the same, the distance from one side to the other differs by around 5ft. This means that on one arm there is nearly 6ft inside the loft space but less than 5ft on the other - which all gives rise to a funny hip on the corner of the roof which doesn't show very well on Google Maps purely due to the direction the sun was when the photo was taken. On site its hard to get far enough away from the house down the hill on the relevant sides (due to adjacent properties) to get a good sight line - in terms of solar its great because its above everything, but its tricky to survey. Having read through the cheaper quote again, they appear to be a bit more cautious about putting panels near the edge of the roof to avoid the wind getting under them - which on an exposed site might be a wise precaution.

I'm aware that the split presents potential challenges so we are specifically asking about how the system deals with that.

Martyn1981

WestonDave wrote: »

Hope this is an OK place to ask this but getting confused with solar quotes. If there is a better place (and I'm concious that this board gets cluttered with new threads so didn't start another!) please point me in the right direction.

Have a L shaped roof near Bristol which gives us south east and south west aspects roughly evenly split.

Any thoughts (and anyone think of any companies in the Bristol area worth getting to quote for a third/final option).

Thanks

Hello Dave. Firstly can I repeat what Eric said, (Edit: and Graham) please, please, please ensure that the chosen inverter you finally go with is a dual MPPT. It might seem silly us both pointing out the obvious, but a surprising number of people crop up on here with systems that have a single MPPT despite multiple roof orientations, or roof pitches.

Two roof orientations, or even roof pitches that aren't close should have an inverter each, or a high quality inverter with 'dual' MPPT. The SMA SBTL range (eg SB3600TL) have good reputations. Don't know much about other brands, sorry. Apologies, lecture over.

My installers last August were very good, and whilst I'm in Cardiff some way from you. They are based in Newport, so may be ok.

I don't want to 'sell them', but they seemed really good (I spoke with 5 different companies). Competitive price, but not dirt cheap. They are a family business, but they also do commercial electrical jobs, power station wiring, hotel refit, 2nd Severn Crossing cable pull etc.

PM me if you want their details. (Or can I post on here, not sure?). You could always mention me, but that might do more harm than good!;)

It was they, that wouldn't install a single system across my two roofs as the pitches are different. Seemed very on the ball.

Mart.

WestonDave

Hi Graham - thanks for that as its not something anyone else has mentioned. Would we be better off given that our SW roof leg is around 1 foot lower (vertical height) than the SE leg?

We've not got any other shading - house next door SE side is same level so once the sun clears that we get unobstructed sunlight (before it clears the sun is so low compared to the panel angle it would be useless anyway!) and next house SW side is lower than us so again the roof will be unshaded.