Solar panels East West House

50Twuncle

We live in a semi in southern UK - with the roof running East / West - not South facing - which I understand is not suitable for solar panels
Why ?
The sun does shine - directly on the back of the house, until midday, then pm - the sun shines directly on the front of the house
Whilst, I can accept that we are not going to get the same amount of solar radiation as a south facing roof - how much less would we get if we fitted panels on the front or back roof ?
In mid summer, on a clear day - we get direct sunlight on the front of the house from 1pm to 9pm, and on the rear from 5:30 until 1pm

theboylard

First of all, welcome to solar central!

Secondly, who said your house isn't suitable?

If it's a rent-a-roof company, they want to cherry pick the easiest/best rooves to get on, so south or south west.

Are you buying the install or after a freebie? If the latter, then the company has given their verdict. You can try some others but watch the contract terms, some mortgage companies do not like rent-a-roof companies and you may struggle for remortgage or on a sale, where the buyers mortgage company refuses to entertain a mortgage with a covenant.

If it's anyone else, they are taking out of another orifice!!

If your house is true east/west, then get panels on both.

Post up rough location, if there is any shading on either roof (from chimney, TV aerial, velux window etc), roof sizes and pitch angle.
Last 2 don't have to be deadly accurate, but roof size will dictate size of install so pictures may help.

50Twuncle

theboylard wrote: »

First of all, welcome to solar central!

Secondly, who said your house isn't suitable?

If it's a rent-a-roof company, they want to cherry pick the easiest/best rooves to get on, so south or south west.

Are you buying the install or after a freebie? If the latter, then the company has given their verdict. You can try some others but watch the contract terms, some mortgage companies do not like rent-a-roof companies and you may struggle for remortgage or on a sale, where the buyers mortgage company refuses to entertain a mortgage with a covenant.

If it's anyone else, they are taking out of another orifice!!

If your house is true east/west, then get panels on both.

Post up rough location, if there is any shading on either roof (from chimney, TV aerial, velux window etc), roof sizes and pitch angle.
Last 2 don't have to be deadly accurate, but roof size will dictate size of install so pictures may help.

OK I admit that I made the mistake of assuming that my roof is not suitable - from reading up about panels - I have it stuck in my head that a south facing roof is required
The roof is not shaded by anything - except a stumpy chimney to one side of our property
We live in the SW of England
The idea is to buy the panels ourselves
We own the house outright
It does run East West
Roof size - about 15 feet * 15 feet (as a guess) !! - the 3rd roof side is a sloping roof at 90 degrees to the 2 sides (a HIP roof I believe ? )
Roof angle is unknown - I would say pretty standard (not oversteep - not overshallow) about 35 degrees (how does that sound ?)
thanks

pinnks

I live in Wiltshire and my roof is about 20 degrees south of due west and about 40 degree slope. I have 3.5kWp using 14 250Wp panels. Projected annual production is about 2,800 kWh and in the first 12 months I got about 150kWh over the estimate.


You'll find that you don't generate a whole lot until the sun pokes its head round to the west of south just around midday. I get about 150-200W through the morning, rising to about 450-500W before it shoots to max production within about 30 minutes of the sun hitting the panels.


The other bonus, which is more a summer thing, is that you generate late into the evening when the sun goes down, whereas a south facing array would probably shut up shop much earlier, or drop to a few hundred watts like mine does in the morning.


If your chimney is in the north end of the roof you can ignore it. If it is on the south end and at the ridge you can also pretty much ignore it as the level of production at the time the chimney makes its shadow is in the hundreds of watts. Once the sun pokes its head round to the panels the chimney will be casting its shadow on the east side of the roof.


When I was getting quotes the suggestion was that I would get about 10% more on a south roof. I now have an array of half the size on my 20 degree east of south roof and get about 10% more from that size for size, though my chimney does impact on tat array from 1pm in the winter and about 4pm in the summer, so without shading I would get a bit more.

50Twuncle

Thanks - looks promising
The chimney is to the south - between us and the neighbour !!
Just one question - is the max output permitted under FIT 4kw ?

Sea_Shell

We've got an East/West roof too and i've often wondered if you could just have half the array on the front, and half on the back, and get the best of both worlds?!

Or can you not do that?

tunnel

An E/W split should produce around 80% of that of a S facing roof.
As has been stated though you'll enjoy a longer sustained generation than that of a south facing roof as one system fades out and the other comes into play.
You could look at going bigger than 4kWp if the roof permits.


Just noticed you have that southside chimney, you may need some sort of shade management like solaredge or micro inverters to benefit the most and NO...you are not restricted to 4kWp, going over that threshold only means a slightly lower FiT rate.

pinnks

The reference to 4kW is the point at which the FiT reduces but you will need permission from your DNO (not sure what the acronym means but its the local grid operator) to go over 3.628kW. You can have 4kWp panels but the inverter must throttle back to limit output in those circumstances.


Over 4kWp the FiT drops by about 10% (I think) for the whole array (if everything installed as one system, but only for the new array if you install one system and then extend it later with another one), so if you want to do that you might want to consider maxing out on a split E/W system. i.e. go for something like the BenQ or SunPower panels that run to about 330W rather than the "normal" 250W and then max out both rooves. This would cost more of course but would mean you are well-supplied with power from sunrise to sunset.

Martyn1981

Hiya 50Twunkle and Sea Shell. Nothing wrong with E/W, just a smaller annual generation than a south facing system. As Tunnel says, probably 80%. You can work it out quite accurately using PVGIS, there's a walkthrough in section 5 of the PV FAQs.

As pinnks says, if you install a big system that can generate more than 3.68kW, then the DNO (it stands for district network operator, the guys that look after the cables, eg Western Power Distribution in my area) has to be asked first for permission. But .....

..... since an east and west system will never max out at the same time, you could install 2.5kWp on the east and another 2.5kWp on the west and run them through a single 3.68kW capped inverter. You would take a 10% hit on the FiT, but you'd have lovely generation right through the day.

Take a look at mine (and tunnel's and pinnks autosignatures) for proof that we've put our money where our mouths are.

Mart.

theboylard

50Twuncle wrote: »

OK I admit that I made the mistake of assuming that my roof is not suitable - from reading up about panels - I have it stuck in my head that a south facing roof is required
The roof is not shaded by anything - except a stumpy chimney to one side of our property
We live in the SW of England
The idea is to buy the panels ourselves
We own the house outright
It does run East West
Roof size - about 15 feet * 15 feet (as a guess) !! - the 3rd roof side is a sloping roof at 90 degrees to the 2 sides (a HIP roof I believe ? )
Roof angle is unknown - I would say pretty standard (not oversteep - not overshallow) about 35 degrees (how does that sound ?)
thanks

Assumption - the mother of all expletives...!!!

We've all done it, so no harm, no fowl

A suggestion - if you can zoom into google maps on your home (might be easier on a mobile device, by taking a screenshot?) and take a snap of your house, if you post the pic here then we can suggest options for you to consider?


Here's mine, and you can see the chimney shadow that caused me s much grief in the second pic...

Hobbo2006

E/W works well for us. Approx 3200kWhs per year. See signature for split.