East/West facing roof - any point in solar panels

Hi Filikin
You can still fit the solar panels on your roof, you would be fitting half of your solar collector on the east side of the roof to catch the morning sun and the second solar collector would be fitted on the west side for the afternoon sun.
In the morning the east facing solar panel would heat the water, and the west facing solar panel would work in the afternoon.

What angle is the pitch on your roof as this also has to be considered?

CC

At this angle you won't get much to cover the DHW consumption. Have you thought about fascade mounted ST collectors on the south side - if possible?

It can be technically done as proposed (East-West at 25-30 degrees), however, but the initial investment plus maintenance can hardly be justified. Neither in monetarian nor ecological units.

Assuming due east/ west roof with a 35 degree pitch and no shadowing on the roof (house is in offaly), any estimate as to the effectiveness during spring/ late autumn of a 6m2 vacuum panel solar system with 3m2 on each side of the roof?

Thanks for any opinions/ wild guesses as to what part of the year my solar heating season would start and finish...

S

Just married a year so only the two of us so two showers a day, but who knows down the line, I'd like to size for 5 if possible

Mothman wrote: »

I'm curious with the focus on west side first. In my experience of recording sunshine, there is more sunshine in morning and arguably makes up for the higher ambient temperature during the afternoon. We get more cloud in afternoon because of convection which is what produces showers

Here are the sunshine hours ignoring the hour either side of midday at my location.
Year, am, pm hours
2006 603, 538
2007 568, 539
2008 513, 469
2009 537, 513

That is brilliant! I have been looking for info like this for ages. Can you tell me if the radiation figures are horizontal or are they pitched at an angle?

I had heard that we experience more cloud in the early afternoon alright from your experience does this dissipate later in the afternoon?

Great info here. There are two reasons for favouring west over east, but they may well be discounted by the sunshine.

1) The ambient temperature is higher in the afternoon, therefore flatplate panels will be more effective. This wouldn't apply to tubes
2) Most hot water use is at night, so hot water from a west panel is stored for a shorter time with less heat loss.

With heat pipe type vacuum tube systems, going east west doesn't require a second pump. With flatplates or direct flow systems, you do need to prevent pumping hot water through a cold panel. That's also a factor. Q

The energy you use for the shower does appear to be very excessive, if say for two people. It would be no harm to try and reduce your needs, costs nothing. Are you a BB. The New Boiler is a good step. Have you installed separate zones, ie DHW / Heating. The solar panels may be installed on the wall.

soldsold wrote: »

The last couple of days have changed my mind on east-west vs south facing solar panels. My south facing roof is slightly shaded by two gables, but this morning the snow on the south side had totally melted by early morning, and the East and West didn't melt all day.

Also the south facing roof is much lower so easier access for replacing vacuum flasks down the line.

So my conclusion has to be to put the solar panels on the south facing roof, even though its slightly shaded...?

You're right to want ease of access, but the key point is that putting panels on east or west roofs will lose 20% to 30% of the output of a solar panel, depending on the roof slope. If your south roof is shaded for less than 25% of the time, it makes more sense.

Your argument about the winter sun melting snow may be the source of a useful epiphany, but may not be entirely relevant. In winter time, the sun is much lower in the sky, and gives very little heat in the morning and evening on east and west sides. It isn't quite so useless in the summer.

soldsold wrote: »

Because my place will be airtight and very well insulated (10-12 inches of different types of insulation all around with minimal cold bridging, triple glazed 0.7 u value windows), I'm more concerned with extending the heating season than getting performance in summer, so I'm installing 6m2 of vacuum flasks.

Do you still think south facing is best? South is also the front of the house and It looks good now but a load of vacuum flasks will take from the look of the house.

If you want to extend the season, again, because of the lower sun in spring and autumn morning/evening, you would be better off on the south. If you pm me your geographical location, roof pitch of each roof, and an email address, I can email you back a simulation of each option (I can't post it here as an attachment because the software puts company logos on the pdf).

My guess is that you will see the east/west output more dramatically changed in spring and autumn - exactly the effect you don't want.

Over the years since we built out house, we have become less concerned about aesthetics, and more concerned about practicalities. We have a sod roof and went to a lot of trouble putting the panels in the wrong place in order not to spoil our elegant roof line, but we moved them later. But that's all a matter of taste - if there was only one correct answer, there would only be one type of panel in the world

I would go for one of the flask systems that comes with black frames and manifold rather than the shiny stainless stuff. I think in the long run, solar panels are going to become part of the vernacular in architecture, and will become less conspicuous as that happens.:)