Solar Panels?

[AdamV12V]

Dave726 said:

In case it helps you, I have a 26.27kW GSE in-roof and Solion ballasted bin mounted system installed on 2 pitched and 2 flat roofs which are on average 53 degrees off South (according to installer, I think they are more like 30 degrees off South) in Surrey. The pitched roofs are quite steep pitches and the lower pitched roof and lower flat roof have a bit of shading (although the installer classified it as shade factor of 0.98) and my total generation in December was 295.73kWh. Lowest day was 1.72kWh and highest was 22.5kWh

Thank you, yes that's helpful - it does seem to tie in with estimates then, albeit they err a little on the pessimistic side, which I was told any "official calcs" always would be.

[romft123]

OutInTheShed said:

The poor generation predicted in Dec/Jan is due to the near-horizontal panels.

Typical data is in the region of 5:1 or even 4:1 for July vs January, with a suitably pitched roof.
You're seeing 10:1, due to the low angle of sun in the winter
But you've got more panels in the equation than most.


Personally, my bills are currenty split roughly evenly between gas and electricty.
Four months of winter dominate the gas bill but the electicity use is only maybe 30% up in Winter?

I am looking to move from this modern house to something older and less efficient.

Horizontal panels....kerikeeee. My 14 panels are mounted on a scaffold tiltable frame that I rotate every month or so to align up perfectly. Some say you can get a near 20% increase in juice.

[AdamV12V]

OutInTheShed said:

The poor generation predicted in Dec/Jan is due to the near-horizontal panels.

Typical data is in the region of 5:1 or even 4:1 for July vs January, with a suitably pitched roof.
You're seeing 10:1, due to the low angle of sun in the winter
But you've got more panels in the equation than most.

Yes the near flat pitch hurts us most in winter, but actually boosts output in Summer. Overall the flat pitch generates more electric over the whole year however.

If I change the pitch in the calculations to 35 degrees instead of 2.5 degrees the following happens.

July falls from 6,375 kwh pa to 5,482 kwh pa
Dec grows from 593 kwh pa to 829 kwh pa
Overall however our output would fall from 42,482 kwh pa to 36,918 kwh pa.

So yes our ratio of 10.75:1 summer:winter changes to 6.61:1 with a pitched roof.

However over the whole year, the 2.5 degree roof actually generates 15% more electricity, albeit at the wrong time of year. Still its 15% more to sell over the whole year, slightly clawing back some of the losses in winter. Probably all made even more extreem given we are in up north in Leeds, rather than down south as many of you are. So our summer days are a bit longer and our winters days are a bit shorter.

Please bear in mind that my calcs are affected by the fact I have a north and a south roof there, so whilst a 35degree pitch would help the southern roof, it would hugely hinders the northern facing roof, hence my total is what is it. That said the very fact we have a flat roof is what makes the larger 60% area of the northern roof feasible. If the roof was pitched we would have a less than half the total solar to play with, albeit half the capital outlay too.

So yes its a very interesting dynamic pitch, but my pitch is 2.5 degrees like it or not, and I do not want to change the aesthetic of the flat roof.

Edited by AdamV12V on Saturday 6th April 15:23

[dmsims]

@AdamV12V

You haven't said what the costs are ?

[AdamV12V]

dmsims said:

@AdamV12V

You haven't said what the costs are ?

Haven’t finalised them yet, but all in all, i suspect it will be around £120k over the cost of a new roof alone, but without solar or batteries the new pool and switch from gas to electric heating likely push our fuel bills way over £12k pa.

[dmsims]

That is toppy!

Have you considered ground mount?

[AdamV12V]

dmsims said:

That is toppy!

Have you considered ground mount?

The tiles are expensive yes, but i have an aesthetic issue to solve with the roof anyway.

Ground mounted does not interest me at all as it does not solve the roof aesthetic and replacement issue and it only creates an eyesore in the garden. Aesthetic considerations are probablu higher to me than the actual income aspects.

[Cheib]

Re wind turbine…the costs don’t add up. As has been said they are noisy….installation costs are high, the turbines themselves are obviously expensive, they need servicing annually etc etc. There’s a reason there are very few suppliers to what you might call the domestic UK market. As I understand it the bigger they are the more efficient they are so the economics of the ones we see supplying the grid are very different.

[Cheib]

Does anyone ever look at the “Gary does Solar” YouTube channel…his presenting style is a but dry but I’ve found it quite a good resource for getting me up the learning curve.

There is new “guidance” from British Standards on installation of batteries. Shouldn’t be installed in lofts, should have ventilation should be fire resistant barriers.

It is all recommendations at the moment but as he points out it is likely to become mandatory in the future, I’d been thinking about the fire risk from batteries as they are likely going to be installed in a room at the back of our house which currently houses pump/heater for swimming pool. Luckily it is away from the main part of the house/bedrooms but the fire retardant issue is worth thinking about. As he points out if it does become mandatory if you want to upgrade/replace/add batteries in the future you might not be able to in an existing installation which doesn’t comply.

https://youtu.be/uzZ51Xh0PwM?si=GZI3Z39oWSbrGe1J

[Mr Penguin]

Cheib said:

Re wind turbine…the costs don’t add up. As has been said they are noisy….installation costs are high, the turbines themselves are obviously expensive, they need servicing annually etc etc. There’s a reason there are very few suppliers to what you might call the domestic UK market. As I understand it the bigger they are the more efficient they are so the economics of the ones we see supplying the grid are very different.

It isn't something you would put in a normal garden but it can work for some people with the space to put it far from the house and be able to have it high enough that the wind isn't obstructed by trees and houses. If you are one of those people then it gives more electricity in the winter so doesn't have the seasonal issue of solar and would work well in this sort of setup.

There is one near me, it is 40m from the owners' house, and I cannot hear it on the road which is 60m away. So if you have a few acres then it is doable IMO.

[OutInTheShed]

Quite a few farmers have small wind turbines.
I think there is a minimum size at which they are cost-effective unless you're seriously off-grid or have other special considerations.
That minimum isze is probably falling as cheap units in the 'few kW' range come in from China.

[silentbrown]

AdamV12V said:

seems hard to believe a 56kwp array would only generate 20kw during a typical whole a day in december, thats barely 30mins of generation. ???

Believe it. It's a perfect storm of stuff that goes on over winter.

Midwinter sun only reaches ~20 degrees above horizon in UK, so the low angle of your panels means you're only catching about 30% of available power
on the south aspect, 20% on the north aspect.

Low sun means more atmospheric attenuation
Much shorter days
More cloud, rain etc.
And potentially snow, which isn't going to slide off a 2.5 degree roof of it's own accord...

Our 4.6kW array averaged 2kWh/day in December...

[sfella]

Mr Penguin said:

It isn't something you would put in a normal garden but it can work for some people with the space to put it far from the house and be able to have it high enough that the wind isn't obstructed by trees and houses. If you are one of those people then it gives more electricity in the winter so doesn't have the seasonal issue of solar and would work well in this sort of setup.

There is one near me, it is 40m from the owners' house, and I cannot hear it on the road which is 60m away. So if you have a few acres then it is doable IMO.

Friend has one on a Hill nearby, 60k in planning fees, 300k install costs. Produces 100kwh in perfect conditions at 15p a kW. Its constantly broken it seems at great cost and even produced a lightning strike which caused him a load of grief

[dobly]

AdamV12V said:

Plan is to fit an ASHP and a MVHR to recover heat as circulated, seal up the house to near passivehaus spec. ASHP will likely be in the range of 17-22Kw depending on final room configuration for wet underloor heating, and topped up with some electric matting for the rooms where wet isnt possible. I suspect we are going to be in the 25kw zone for total electric heating, plus the swimming pool.

Edited by AdamV12V on Saturday 6th April 13:41

We looked at getting an ASHP with an output in the region of 20kw (to heat radiators) but couldn’t find anything that was larger than 14kw that was at all efficient.
You may be able to get two (or more) units in a cascade arrangement with buffer storage to work for your situation.
We don’t have gas and want to move away from fossil fuels (in our case diesel) and don’t have the rooftop solar capacity as most of our roof is slate, which isn’t compatible with solar panels. If we could get Tesla Solar roof tiles we would, but they aren’t available in our location.
So we are going with a pellet boiler from Oekofen - which can be linked to their ASHP (not that we will be doing this).

[Mars]

dobly said:

...and don’t have the rooftop solar capacity as most of our roof is slate, which isn’t compatible with solar panels.

Not sure how different yours are but mine are slate and I have 21 panels mounted through them.

[Road2Ruin]

Mars said:

dobly said:

...and don’t have the rooftop solar capacity as most of our roof is slate, which isn’t compatible with solar panels.

Not sure how different yours are but mine are slate and I have 21 panels mounted through them.

You can also get an 'in roof' system, where the panels replace the slates and then they fill in around them. It looks quite smart.

[OldSkoolRS]

silentbrown said:

AdamV12V said:

seems hard to believe a 56kwp array would only generate 20kw during a typical whole a day in december, thats barely 30mins of generation. ???

Our 4.6kW array averaged 2kWh/day in December...

Just a further data point: Our 5.5kW array averaged 2.7kWh/day in December, so proportionally very similar.

Compare that to 28.3kWh/day in June, which means on average we would export over 22kWh/day in June which more than helps cover our shortfall in winter when we use approx 220kWh/month.

[dmsims]

Indeed plenty of solar on slate. there are special moutings, you don't want to be drilling through them!

https://www.geniusroofsolutions.com/product/solarf...

Mars said:

Not sure how different yours are but mine are slate and I have 21 panels mounted through them.

[Cheib]

Mr Penguin said:

Cheib said:

Re wind turbine…the costs don’t add up. As has been said they are noisy….installation costs are high, the turbines themselves are obviously expensive, they need servicing annually etc etc. There’s a reason there are very few suppliers to what you might call the domestic UK market. As I understand it the bigger they are the more efficient they are so the economics of the ones we see supplying the grid are very different.

It isn't something you would put in a normal garden but it can work for some people with the space to put it far from the house and be able to have it high enough that the wind isn't obstructed by trees and houses. If you are one of those people then it gives more electricity in the winter so doesn't have the seasonal issue of solar and would work well in this sort of setup.

There is one near me, it is 40m from the owners' house, and I cannot hear it on the road which is 60m away. So if you have a few acres then it is doable IMO.

We do have the space as we have a paddock and it is open to westerly winds so is actually a good potential site (although we’re not coastal so not optimal by any means) but you need to spend serious £££ to get one sipplied and installed by someone who you could rely on for any kind of warranty (good luck with some overseas suppliers). When I looked a couple of years ago I think the turbine itself started at £30k plus all the infrastructure needed around it and installation etc.

I think you’re looking at a high five figure sum plus you need batteries as obviously you need to capture the electricity that would be generated overnight.

I really struggled to find anyone supplying domestic properties,

At that price solar/batteries are more reliable and have less maintenance etc. The latter is between £500 and £1000 a year from memory.

[silentbrown]

AdamV12V said:

Haven’t finalised them yet, but all in all, i suspect it will be around £120k over the cost of a new roof alone, but without solar or batteries the new pool and switch from gas to electric heating likely push our fuel bills way over £12k pa.

How much of that is the batteries?

In winter, you said you're consuming 1500kWH/month for just heat/dehumidity, so maybe 2000kWH total?, yet producing under a third of that. Your batteries really aren't going to be used much at all, particularly if you use the house itself like a thermal store.

Yet in summer, when your consumption is less, your batteries are seriously oversized for your own consumption, and are basically only that big for time-shifting your export to get around a potential DNO restriction. Which as mentioned, is probably not a good way to bet even in the medium term.

Batteries are easy to add, and prices are still dropping. I'd probably do the S-facing 'pitch' with around 30kWH of storage, and see how that pans out for a year.

Do you have to replace both roof pitches at the same time - and is the N pitch hidden enough that your could have conventional panels on that rather than a solar roof?