Siting of panels for solar water heating

We moved into our two storey, reconstituted stone-built, pitched-roof house in April.
We decided early on to get as much of our energy as possible from renewables.
A couple of weeks ago we signed up for a solar heating system. I've looked at a few and this seems like a very good system.
The marketing wonk who visited us (who had obviously been in the pub first) declared that our directly west-facing roof would be perfectly adequate to site the panels. It is a very clear prospect as it faces a flat field, and there are no trees in the line of sight.
However, when their surveyor came to measure up he said that the west-facing roof was inadequate and the panels would have to be sited on the gable-end wall (facing south).
I can't see how this would be an improvement. Even though the panels would be angled away from the wall (mimicing the roof's pitch) they would certainly be obscured by the angle of the roof for at least part of the morning and part of the evening.
Am I wrong? The alternative, according to the surveyor, would be double the number of panels with half on the east pitch and the other on the west.
Many thanks
Will.

"Will" wrote:

We moved into our two storey, reconstituted stone-built, pitched-roof house in April.
We decided early on to get as much of our energy as possible from renewables.
A couple of weeks ago we signed up for a solar heating system. I've looked at a few and this seems like a very good system.

Watchdog 'did' the solar energy industry on BBC 1 last Tuesday evening. Their conclusions were that there a lot of rogue companies, the estimates for equipment and installation are very inflated (�12,000 in one case for a non-working system), the claimed energy benefits are often very exaggerated, the salesmen talk a lot of dishonest rubbish, and a lot of properties are not suitable. My understanding is that the panels need to be mounted on a south-facing aspect. Got a long bargepole?

We moved into our two storey, reconstituted stone-built, pitched-roof house in April.
We decided early on to get as much of our energy as possible from renewables.
A couple of weeks ago we signed up for a solar heating system. I've looked at a few and this seems like a very good system.
The marketing wonk who visited us (who had obviously been in the pub first) declared that our directly west-facing roof would be perfectly adequate to site the panels. It is a very clear prospect as it faces a flat field, and there are no trees in the line of sight.
However, when their surveyor came to measure up he said that the west-facing roof was inadequate and the panels would have to be sited on the gable-end wall (facing south).
I can't see how this would be an improvement. Even though the panels would be angled away from the wall (mimicing the roof's pitch) they would certainly be obscured by the angle of the roof for at least part of the morning and part of the evening.
Am I wrong? The alternative, according to the surveyor, would be double the number of panels with half on the east pitch and the other on the west.

Have you checked with the local planners that you don't need their permission? Quite a lot of people get caught out with this.
Peter Crosland

On 16 Nov 2006 12:09:52 -0800, "Will" wrote:

We moved into our two storey, reconstituted stone-built, pitched-roof house in April.
We decided early on to get as much of our energy as possible from renewables.
A couple of weeks ago we signed up for a solar heating system. I've looked at a few and this seems like a very good system.
The marketing wonk who visited us (who had obviously been in the pub first) declared that our directly west-facing roof would be perfectly adequate to site the panels. It is a very clear prospect as it faces a flat field, and there are no trees in the line of sight.
However, when their surveyor came to measure up he said that the west-facing roof was inadequate and the panels would have to be sited on the gable-end wall (facing south).
I can't see how this would be an improvement. Even though the panels would be angled away from the wall (mimicing the roof's pitch) they would certainly be obscured by the angle of the roof for at least part of the morning and part of the evening.
Am I wrong? The alternative, according to the surveyor, would be double the number of panels with half on the east pitch and the other on the west.
Many thanks
Will.
Its a little difficult to visualise the gable end of the roof, but it

sounds at though your roof ridge runs north/south, which is really as bad as it gets for placing solar panels (presumably water heating, not space heating?). Technically your surveyor is right - in the northern hemisphere they should face south at approximately the angle of your latitude. I don't understand, from your description, how they can "mimic" the roof pitch, unless there is a small angled roof facing south - in which case that is where the panel should be placed. In practice you may need to make a compromise if your roof has wrong angles. But remember its an expensive installation, so you want to capture the greatest amount of solar insolation possible.
Of course, if the panels were for space heating, you might want the greatest input in the morning, in which case the east facing roof might be better. There are a number of factors to consider.
Best wishes Eric Sears.
Eric Sears

"Eric Sears" wrote in message

Technically your surveyor is right - in the northern hemisphere they should face south at approximately the angle of your latitude.

Correct, and a little shade in the early morning and late evening is neither here nor there as there's little heat in the sun's rays at those times. Look at graphs for solar energy vs time of day, and vs orientation, angle, etc.

I don't understand, from your description, how they can "mimic" the roof pitch, unless there is a small angled roof facing south - in which case that is where the panel should be placed.

He just means that they'll be mounted at an angle rather than vertically.

Of course, if the panels were for space heating, you might want the greatest input in the morning, in which case the east facing roof might be better. There are a number of factors to consider.

Solar panels for space heating! How daft is that! Who needs heating April-September? If you do, it'll be because the sun isn't shining... These things provide some heat at other times, but not enough to get your cylinder hot let alone heat the house! Super-insulated eco-houses excepted, of course.
Mark

"Peter Crosland" wrote in message

However, when their surveyor came to measure up he said that the west-facing roof was inadequate and the panels would have to be sited on the gable-end wall (facing south).
Have you checked with the local planners that you don't need their permission? Quite a lot of people get caught out with this.

Good point. You can normally fit panels to the roof without PP if they don't protrude more than about 100mm, but sticking them on a gable end at an angle probably will require PP.
To be safe it's best to get a letter from the local planning dept even if no PP is required, to help speed the inevitable solicitor's queries when the time comes to sell. I did for mine, in fact I delayed placing my order until it was in my hands.
Mark

"Will" wrote in message

We moved into our two storey, reconstituted stone-built, pitched-roof house in April.
We decided early on to get as much of our energy as possible from renewables.
A couple of weeks ago we signed up for a solar heating system. I've looked at a few and this seems like a very good system.
The marketing wonk who visited us (who had obviously been in the pub first) declared that our directly west-facing roof would be perfectly adequate to site the panels. It is a very clear prospect as it faces a flat field, and there are no trees in the line of sight.
However, when their surveyor came to measure up he said that the west-facing roof was inadequate and the panels would have to be sited on the gable-end wall (facing south).

From our experience with our very good south-facing solar panel I'd say that the surveyor was right. The sun's rays will only be falling on a west-facing panel for part of the day and in winter they'll be too low to be effective.

I can't see how this would be an improvement. Even though the panels would be angled away from the wall (mimicing the roof's pitch) they would certainly be obscured by the angle of the roof for at least part of the morning and part of the evening.
Am I wrong? The alternative, according to the surveyor, would be double the number of panels with half on the east pitch and the other on the west.

That would make it very expensive.
We only looked into the system because we had a directly south facing pitched roof, if we'd not had that we wouldn't have considered it.
I don't know what your system is but suspect it can't be the same as ours, our company was very straight with us. In fact, because we did the work ourselves, nobody visited, they didn't need to.
Mary

Many thanks
Will.

On 16 Nov 2006 12:09:52 -0800, Will wrote:

However, when their surveyor came to measure up he said that the west-facing roof was inadequate and the panels would have to be sited on the gable-end wall (facing south).

I'd go with the surveyor. Maximum solar input is at midday, the sun is due south at midday, you want to present the largest surface area to the incoming radiation that you can to capture the most energy.
Early morning and late evening with the sun low in the sky has much less energy available than midday.
-- Cheers new5pam@howhill.com Dave. pam is missing e-mail

On Thu, 16 Nov 2006 21:11:51 -0000, "MarkK" wrote:

"Eric Sears" wrote in message
Technically your surveyor is right - in the northern hemisphere they should face south at approximately the angle of your latitude.
Correct, and a little shade in the early morning and late evening is neither here nor there as there's little heat in the sun's rays at those times. Look at graphs for solar energy vs time of day, and vs orientation, angle, etc.
I don't understand, from your description, how they can "mimic" the roof pitch, unless there is a small angled roof facing south - in which case that is where the panel should be placed.
He just means that they'll be mounted at an angle rather than vertically.
Of course, if the panels were for space heating, you might want the greatest input in the morning, in which case the east facing roof might be better. There are a number of factors to consider.
Solar panels for space heating! How daft is that! Who needs heating April-September? If you do, it'll be because the sun isn't shining... These things provide some heat at other times, but not enough to get your cylinder hot let alone heat the house! Super-insulated eco-houses excepted, of course.

http://www.sunwarm.com/ These sent us a leaflet Thats for new build only I think but they do a retro fit solution too. I'm not entirely convinced but I do know the south side of my house in winter during the day is very toasty but the north side isn't.

Mark

"Will" wrote in message

Am I wrong? The alternative, according to the surveyor, would be double the number of panels with half on the east pitch and the other on the west.

South facing or just West of South, but certainly not West.

On 16 Nov "Will" wrote:

I can't see how this would be an improvement. Even though the panels would be angled away from the wall (mimicing the roof's pitch) they would certainly be obscured by the angle of the roof for at least part of the morning and part of the evening.

I would cancel the order until the details are worked out.
If this is for space heating, then both the east and west facing slopes are no good unless the panels are mounted at a complex angle so that they face south and up at an angle according to latitude (to get more heat in winter than summer, plus 23 degrees, which at north 50 degrees, approaches vertical). Vertical south facing walls are best for the most heat in the winter in higher north latitudes.

Am I wrong? The alternative, according to the surveyor, would be double the number of panels with half on the east pitch and the other on the west. Will.

For a millionaire, sure. Most installations have the panels at the same angle as the roof, but only when the roof slopes south (in the northern hemisphere), but HVAC experts know that for thermal energy, and not solar electric, vertical mounting on a south facing wall is best for maximum heat in winter.
But the type of panels might make a difference, air panels without storage might heat certain rooms, like the kitchen and bath in the morning, and other rooms later in the day. Drain-down water panels with thermal storage really should be tracking panels to get the most heat, and tracking is not implemented as much as it should be.
If the panels are mounted on the west slope, and there is no concern about the appearance, then they could be angled toward the south, but would need space in between panels so that no panel makes shade on another panel.
If there is enough yard space, it might be better to mount the panels on a platform a few feet above the ground, and have the platform rotate to face the sun.
All it takes for a rotating platform is a post and a couple of wheels to allow rotation, and for better results have an altitude tracking system, ask about the tracking here.
In general, east and west facing roof slopes are not good for solar water heating unless the pitch is shallow, and the panels are angled to the south
The roof pitch should be ignored, and the panels mounted so they get the most direct sun, but sometimes that makes an unsightly installation.
Panels on the south facing wall sounds good, especially if the wall has enough area, but tracking would be better.
Joe Fischer

1.Do not do anything until you have looked at Navitron's website. 2. Solar panels do not have to be high up - I know at least one geezer who has them at ground level and another who has one on his garage. 3. Do not believe ignoramuses who suggest that you will not get much heat - that did apply to the old flat panel stuff, still being sold by B&Q, but the vacuum tubes now being used on the continent are vastly superior. I recently went to a demo and noted a cylinder water temperature of 48 c being obtained on a relatively cloudy and cool day. I am reliably advised that on a warm summers day, the tube manifold can reach well over 100 c and hence so much heat is being soaked up that one can have 3 to 4 free baths and still have to dump excess heat into a loft radiator - that's how good they are. 4. If you have already signed up and paid a deposit for a flat panel system do your best to get out of it. 5. I will probably be putting in a Navitron system myself soon with help from plumber brother for around �900. The B & Q deal for �1500 is a total rip off and the energy savings will take at least 15 years to recover. "Will" wrote in message

We moved into our two storey, reconstituted stone-built, pitched-roof house in April.
We decided early on to get as much of our energy as possible from renewables.
A couple of weeks ago we signed up for a solar heating system. I've looked at a few and this seems like a very good system.
The marketing wonk who visited us (who had obviously been in the pub first) declared that our directly west-facing roof would be perfectly adequate to site the panels. It is a very clear prospect as it faces a flat field, and there are no trees in the line of sight.
However, when their surveyor came to measure up he said that the west-facing roof was inadequate and the panels would have to be sited on the gable-end wall (facing south).
I can't see how this would be an improvement. Even though the panels would be angled away from the wall (mimicing the roof's pitch) they would certainly be obscured by the angle of the roof for at least part of the morning and part of the evening.
Am I wrong? The alternative, according to the surveyor, would be double the number of panels with half on the east pitch and the other on the west.
Many thanks
Will.

On 16 Nov 2006 12:09:52 -0800 Will wrote :

However, when their surveyor came to measure up he said that the west-facing roof was inadequate and the panels would have to be sited on the gable-end wall (facing south).

You might want to download SAP2005 from www.bre.co.uk/sap2005
You can leave 95% of it to people like me, but Appendix H will give you some hard numbers. Table H2 gives solar radiation as 724W/m2 on a vertical south facing panel, 886/829 for a west facing panel pitched at 30/45 degrees.
-- Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk

On Thu, Tony Bryer wrote:

On 16 Nov 2006 12:09:52 -0800 Will wrote : However, when their surveyor came to measure up he said that the west-facing roof was inadequate and the panels would have to be sited on the gable-end wall (facing south).
You might want to download SAP2005 from www.bre.co.uk/sap2005
You can leave 95% of it to people like me, but Appendix H will give you some hard numbers. Table H2 gives solar radiation as 724W/m2 on a vertical south facing panel, 886/829 for a west facing panel pitched at 30/45 degrees.

Is that average year-round, or max in January?
for domestic hot water, year round is important, for space heating, the max in winter should be sought.
Pitching the panels south on a west sloping roof really complicates the installation because of trying to position the mounts without causing leaks.
Joe Fischer

In alt.energy.renewable Will wrote:

The marketing wonk who visited us (who had obviously been in the pub first) declared that our directly west-facing roof would be perfectly adequate to site the panels. It is a very clear prospect as it faces a flat field, and there are no trees in the line of sight.

http://rredc.nrel.gov/solar/codes_algs/PVWATTS/version1/ is set up for predicting solar PV installations, but you could make use of the solar insolation for various angles to see the effect of reorienting the panels.
Directly south should be the best. Flat on the wall can be compared to various pitches using the calculator. It might be that flat on a south wall is better than your west-facing pitched roof.
Highlight "Europe" radio button, then select, say, GBR-London. The defaults fall to 180 degree azimuth, 51 degree elevation. That yields "Solar Radiation (kWh/m2/day)" of 3.07. A tilt of 90 degrees yields 2.16. Moving to directly west azimuth, 51 degree tilt is 2.32.
This calculator uses observed sunlight at various locations, so it takes into account the number of sunny days you have in the area as well as sun angles.
-- --- Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5