PV Panels on wsw facing roof

Casper55

Having watched my £10500 worth of shares going up and down the last few years and getting poor returns on other investments( mainly ISAs) I am considering cashing in my shares and going for solar power. My roof is WSW but leaning more to west then SW. The roof is at 30deg and is quite large so will accomadate a lot of panels.
Tesco are currently offering 20% discount on their systems but use SHarp ND panels which I understand are the cheaper not so efficient panels but with the 20% discount will supply and fit a 3.91 KWp (16 Sharp panel) sytem for the same price as EVOenergy which will fit a 2.82KWp (12 Sanyo panel )I understand from what I have read that the Sanyo panels are more efficient 21 percent as appossed to sharp 14.5 % whatever this means)However I can't resist the 20% discount togther with a couple of hundered quids worth of club points.
I have noticed on previous threads, that no one seems to be interested in fitting solar panels unless the panels are facing almost south.
I should add that I am quite a high end user so will use everything which is made even at the hight of summer. The fact that the supply companies are assuming I will be puting in 50% of what I produce and paying me a further 3 pence per KWH for nowt, sounds a win win situation to me.
Your thoughts would be appreciated . Best REgardsCasper

DoctorPaul

I'm in a similar position to you in that our roof faces almost exactly east-west. However we have just invested some of our savings into our mortgage and so are not in a position to buy solar panels ourselves at the moment. Your £10,500 is currently available for you to use as you see fit. If you invest it in a solar panel installation you will not start to recover your investment until approximately 10yrs post installation (considering only the £1030/year government payment). So, assuming you do not have any additional savings tucked away, I think the question is whether you are prepared to lock all of your available savings into your house until you can start to re-coup the investment 10yrs down the line.

I am going to enquire about free solar panel installation on my east-west roof and see what responses I get. Most free installers specify a south facing roof area unfortunately.

reeac

There's a diagram available at www.greenshopsolar.co.uk/content/view/52/46 which shows that with a W. facing 30 degree pitch roof you'll get about 86% of max. output and that rises to almost 90% at 15 degrees S. from due W. In other words it's still viable especially if you can get a 20% discount on the cost.

grahamc2003

reeac wrote: »

There's a diagram available at www.greenshopsolar.co.uk/content/view/52/46 which shows that with a W. facing 30 degree pitch roof you'll get about 86% of max. output and that rises to almost 90% at 15 degrees S. from due W. In other words it's still viable especially if you can get a 20% discount on the cost.

That's an interesting diagram you referenced. I'm not sure if I'm reading it coirrectly. What it seems to say is that, for London, if you have a West facing roof, if the panel is horizontal, then you get about 92% of the energy available - is that how you read it?

Seems a bit counterintuitive to me - I wouldn't have thought the max output for a west facing panel is when the panel is horizontal. Am I understanding this incorrectly?

malch

DoctorPaul wrote: »

(considering only the £1030/year government payment). .

no payment from the government FITs is paid by the electicity companys

Worcester

Casper55 wrote: »

SHarp ND panels which I understand are the cheaper not so efficient panels but with the 20% discount will supply and fit a 3.91 KWp (16 Sharp panel) sytem for the same price as EVOenergy which will fit a 2.82KWp (12 Sanyo panel )I understand from what I have read that the Sanyo panels are more efficient 21 percent as appossed to sharp 14.5 % whatever this means)However I can't resist the 20% discount togther with a couple of hundered quids worth of club points.
I have noticed on previous threads, that no one seems to be interested in fitting solar panels unless the panels are facing almost south.
I should add that I am quite a high end user so will use everything which is made even at the hight of summer. The fact that the supply companies are assuming I will be puting in 50% of what I produce and paying me a further 3 pence per KWH for nowt, sounds a win win situation to me.
Your thoughts would be appreciated . Best REgardsCasper

The ND Panels are Poly Crystalline as opposed to mono crystalline, both cost almost exactly the same price to make, ironically in some countries they prefer poly's for some reason the UK prefers mono's, hence the poly's are cheaper.

The efficiency relates to output W/m2 so you just need a bigger roof / more panels, the Sanyos only seems to add up if you've got a small roof and need the extra output.

Tesco may be a great brand name, however they are not MCS regsitered and have not signed up to the REAL Assurance programme, so please at least ask a local installer to quote before you get wooed by club points and 20% off, most local installers without a salesman's bonus to pay will happily match the tesco price.

Oh and by the way unless you are a MASSIVE user, you will actually be lucky if you can ever consume more than 70% of what you generate.

Even if you have two people working at home, there will be a mismatch between your consumption profile and generation profile, so please don't take more than 70% into your calculations.

Also depending upon your usage profile (most people use more in the morining and early evening than during the day, an East/West split can in some circumstances actually work out better.. And if you talk to the right installers they'll know how to set it up so that you can maximise the tariff band on an East / West installation too.

Casper55

Worcester
Thanks for the reply. I am now begining to understand how it all works. I now appreciate how difficult it would be to use all the energy produced at peak times. I was supprised to hear you say that Tesco are not MCS regersted but will look into it thanks. Also for making the point regarding an east west split and possibly usung more energy early morning and evening So will mention this to the installers.
As both my wife and I are in early retirement, but still hope to be around in 25yrs time. We are lucky to be around for most of the time at home. We also run about a constat 1.5KW during the summer and feel we will be able to top this up during peak times with running various appliance at midday.Hope this makes sense, best regards Casper

zeupater

Casper55 wrote: »

Worcester
Thanks for the reply. I am now begining to understand how it all works. I now appreciate how difficult it would be to use all the energy produced at peak times. I was supprised to hear you say that Tesco are not MCS regersted but will look into it thanks. Also for making the point regarding an east west split and possibly usung more energy early morning and evening So will mention this to the installers.
As both my wife and I are in early retirement, but still hope to be around in 25yrs time. We are lucky to be around for most of the time at home. We also run about a constat 1.5KW during the summer and feel we will be able to top this up during peak times with running various appliance at midday.Hope this makes sense, best regards Casper

Hi Casper55

Having a summer 1.5kW baseload is massive ..... unless you have atypical consumption as a result of running a business from home, air conditioning or about 25 spotlights on almost constantly it's likely to be well below 300W ..... you might want to review this before working out the potential pv savings.

HTH
Z

Equaliser123

We have a WSW facing roof with 14 panels (3.29kwp).

The system actually works better if it is cloudy in the morning and sunny late morning or early afternoon. I am assuming that the cloud diffuses the indirect sunlight back on to the panels. If it is a bright clear morning, the system only produces a constant 200w or so until mid morning when the sun comes round. It then absolutely leaps up.

Evening drop off really only occurs when the sun actually sets so it is still generating useful output (400w+) at 8pm at the moment.

Casper55

zeupater wrote: »

Hi Casper55

Having a summer 1.5kW baseload is massive ..... unless you have atypical consumption as a result of running a business from home, air conditioning or about 25 spotlights on almost constantly it's likely to be well below 300W ..... you might want to review this before working out the potential pv savings.

HTH
Z

My current energy consumption is 1.3kwhs according to mky remote meter. I agree that my base line consumtion would be in the region of 300 watts. but I run a koi pond. If I had up the rated power of all the equipment for the koi Pond it comes to a 1 KW . Total 1.3 KW. I also have a 3 kw heater which I run as sparingly as possible( unfortunately through the night. It will be interesting to see how much of the produced energy I can use. Best Regards Casper

reeac

grahamc2003 wrote: »

That's an interesting diagram you referenced. I'm not sure if I'm reading it coirrectly. What it seems to say is that, for London, if you have a West facing roof, if the panel is horizontal, then you get about 92% of the energy available - is that how you read it?

Seems a bit counterintuitive to me - I wouldn't have thought the max output for a west facing panel is when the panel is horizontal. Am I understanding this incorrectly?

I agree with your stated 92% figure so I think that you're reading the diagram correctly. It's a compicated diagram because I assume that it must cover both the angle of incidence of the sun onto the panel and also the number of hours for which the panel will be exposed to direct sunlight. For example, the horizontal panel will never be in shadow during a long summer day whereas a steeply pitched S. facing one will suffer from the sun rising and setting behind it.