PV Panels on wsw facing roof

dave2012

Casper55 wrote: »

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

A west facing roof will perhaps generate only 80-90% of what a south facing roof will generate. You have to decide whether it's worth it. We have an east facing roof, and have nevertheless decided to install a system - which I believe is about 3.75 kW. We installed before the change in FITs and have the appropriate micro generation certificate, so hopefully we'll get the benefit of the 43+p rates, providing nobody reneges on the deal. We paid just under £13k to British Gas. So far it's been running for about 5 weeks, and we didn't expect to get anything in December or January anyway. According to the Sunny Beam meter we have accumulated about £20 in FIT, and we will have saved a modest amount in electricity. At this rate it'll take over 10 years to recover the initial investment, and from then on it should be fairly good news - providing there are no other maintenance issues or costs. Over 25 years the higher FIT seems good, though as one of my colleagues perhaps unkindly said "why worry about what'll happen in 25 years?"

The newer proposed FITs of around 21p will probably not be very attractive to investors whose only interest is making money.

The costs of panels should drop, and efficiencies should go up - though they almost certainly won't go as high as 40%. According to some sources the breakeven point for PV panels should occur in 2013. That's the point at which costs of production etc. fall below the value of the generated electricity. Obviously a lot depends on who has their fingers in the pie, but I'm guessing that it'll be quite a few years before the panel cost drops to a point where a private investor could go it alone without any governmental support, such as FITs.

One benefit which may arise as panels become more efficient is that it could be possible to exploit more roof area, or use smaller roof areas.

Currently there may be problems with exploiting different facing roof areas, and with problems of shaded panels. This seems stupid to me, but that's the way it seems to be. I would hope that in the future developments could be such that more roof areas could be exploited effectively - but again this will require a reduction in panel cost and efficiency improvements to be economic.

The production costs and installation costs also need to drop significantly before a private investor could go it alone without FIT support. The reduction in FIT is likely to limit the rate at which PV development and adoption proceeds, so expected benefits of PV may be pushed further into the future.

It is possible that putting solar panels for hot water heating may be a better investment. In our household we have a 10kW shower, and most days 3 of us use it for about 5 minutes each. That works out at about 2.5kwH/day, which is now slightly less than we are generating in electricity now. In the summer, I think we can expect to get nearly 7 times as much power generated - based on discussion with other PV owners in the area. 2.5 kwH/day is a bit under 1000kwH/year.

We have a west facing roof also, and on the assumption that the hot water could be supplied by solar water panels, such an installation for heat of the order of 2.5kwH per day would be cheaper, though again one would have to look at the manufacturing costs and installation costs.

Again it's a question of fingers and pies. Many installers will tell you of the benefits, but they often want such a significant part of the action that they leave relatively little for the householder.

Some people who install panels do so for environmental reasons, others for financial. Environmentally they're possibly a good thing, and really should be fitted to all new houses.

If you're only interested in making money, consider that at current rates it's likely that 1000kwH of electricity used would only cost you between £100-£200. Distinguish also between making money, and reducing costs.
You might reduce your costs more by fitting low energy or even LED lights throughout your house, and also by throwing away your fridge or freezer and buying a new one. If you have just one or two rogue electrical devices in your home - perhaps a malfunctioning fridge/freezer (we've had one of those) - then the total electricity drain could be comparable with the cost of installing a PV array on your roof. Replacing poor quality, inefficient devices with significantly better ones may have a greater effect on your bank balance than installing PV arrays.

Of course, if you are looking at longer term investments, then arguably the FITs do that, but you need to work out whether it's worth it for you.

Personally I'm in favour of solar and PVs, and also air source heat pumps, but not everyone is. A few holidays abroad or cruises will wipe out any environmental benefits, though some who do the solar installations will at least feel they are offsetting some of the damage they cause.

A good book to read on energy and the environmental impacts is David Mackay's Sustainable Energy without the hot air - it's available free in PDF form - search for the links.

On the other hand, I do also have more invested in shares than in PV arrays, and right now they are going negative, so in that sense the PVs are a significantly better investment. I did make a small profit on a company involved with wind turbines (Hansen) before it got taken over.

dave2012

Casper55 wrote: »

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

Casper

I have a friend who has thermal solar panels to heat his swimming pool, and also I think he has some solar panels for his hot water. Apparently they are so effective that on one occasion British Gas queried his very low use of gas. For water heating and your pool application you may find that thermal solar panels do save you quite a lot - and if that's your application it'll be much more cost effective than PV. His pool is likely to be larger than your koi pool, so you could find that there are significant savings to be made that way - though obviously you'd need to take care to get the temperatures right. I don't think the pool normally goes above 30 degrees C though, so hopefully your koi would be OK with that.

If you still want to do PVs then I suggest you do solar thermal first for your pool and domestic hot water if you need it, and then use the rest of your roof for your electricity. Thermal panels should be relatively cheap compared to PVs.

Cardew

dave2012 wrote: »

It is possible that putting solar panels for hot water heating may be a better investment. In our household we have a 10kW shower, and most days 3 of us use it for about 5 minutes each. That works out at about 2.5kwH/day, which is now slightly less than we are generating in electricity now. In the summer, I think we can expect to get nearly 7 times as much power generated - based on discussion with other PV owners in the area. 2.5 kwH/day is a bit under 1000kwH/year.

Welcome to the forum.

I don't understand the above.

You appear to be confused between your kW output and the cumulative kWh generated.

You believe you have a 3.75kWp system(you don't say the size of the inverter)

Depending where you live, on a sunny day around noon in summer this could generate 3 to 4 kW. At the time most people shower, in the morning it might be generating 1kW or 2 kW on a sunny morning in summer and nothing in the winter months.

So at best your panels will supply 20% of your 10kW shower's electricity but for much of the year nothing. So of the 900kWh you calculate your electric shower uses(365 x 2.5kWh) I would doubt if your panels produce 10% of that electricity.

Cardew

dave2012 wrote: »

Casper

I have a friend who has thermal solar panels to heat his swimming pool, and also I think he has some solar panels for his hot water. Apparently they are so effective that on one occasion British Gas queried his very low use of gas. For water heating and your pool application you may find that thermal solar panels do save you quite a lot - and if that's your application it'll be much more cost effective than PV. His pool is likely to be larger than your koi pool, so you could find that there are significant savings to be made that way - though obviously you'd need to take care to get the temperatures right. I don't think the pool normally goes above 30 degrees C though, so hopefully your koi would be OK with that.

If you still want to do PVs then I suggest you do solar thermal first for your pool and domestic hot water if you need it, and then use the rest of your roof for your electricity. Thermal panels should be relatively cheap compared to PVs.

The electrical consumption for a Koi pond largely isn't for heating but to run the pumps for filtering - it might be heated in the depths of winter(when solar thermal is producing zilch) but most owners don't.(it is a subject of great controversy)

Solar thermal is something of a joke in terms of money saving. The government commissioned tests(which the solar industry keep quiet about) and on average they produced Hot Water 'worth'(saving) about 1,000kWh pa. - nearly all in Summer. This, if you have gas is worth about £40 pa. EST estimate solar thermal saves on average 5.5% of energy costs and WHICH roughly the same.

ed110220

The exact direction the roof faces doesn't make as much difference to annual generation as you may imagine.

You can put your roof bearing and pitch into the Energy Saving Trust's calculator at: http://www.energysavingtrust.org.uk/Generate-your-own-energy/Solar-panels-PV/Solar-Energy-Calculator. For my location a it gives:-

West, 270 degrees: 2940 kWh/year

West South West, 250 degrees: 3156 kWh/year

South, 180 degrees: 3538 kWh/year