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PV installation advice in Essex

edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
17 replies 4.1K views
cheesengcheeseng Forumite
8 Posts
edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
hi,

I've made the decision to install solar panels as a long term investment and attempt to be a little greener and am looking for some advice.

I have looked at the FAQ pages and a few other threads looking to tips and have learnt a few things but am looking to learn more!

first things first the house details:
roof orientation - S
pitch - 36 degrees
no shading
people int he house - currently 2 but soon to be a family (hopefully)

I started off looking at the Ikea panels (15 panels outputting 4.2KW and battery for 10k) which seemed quite good (but looking at some advice on here seemingly not so great). I will soon make the step to getting quotes using the Which? guide sheet to help me. But I was wondering if anyone had any suggestions for PV installers in Essex?

Also I liked the idea of batteries as I thought this would help increase the benefit of the solar panels - why do most people suggest against batteries?

Is it a good idea to get the biggest system that is viable? would this help "future proof it" incase I get an electric car sometime or for a family of 4 is the average 4Kwh installation ample?

Finally, If we don't get as battery how does a diverter work? I think I have the terminology right, I think I mean the part which diverts excess electricity to heat water - does this work automatically? I saw something about it being hard to exactly guess when to use the immersion but I think this was probably someone who was trying to automate an immersion when there was low power usage rather what a diverter seems to be.

I hope nothing here is too stupid to ask! Many thanks in advance for any advice.
Dave
«1

Replies

  • edited 27 October 2017 at 6:29PM
    HeedtheadviceHeedtheadvice Forumite
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    edited 27 October 2017 at 6:29PM
    Gosh and golly! So many questions after reading lots!

    Cannot answer who to get in Essex. Somebody will soon, no doubt.

    Batteries. A great idea in theory but really for a decent amount of storage still a bit expensive.

    Power output. 4kW is the max you can install without permission. It makes sense to be able to generate as much as possible under non ideal conditions (not so sunny times) so lots of generating capacity (more than 4kW) will enable bigger output under less favourable conditions and give better overall output. The 4kW max can be accommodated with an inverter with a limited in it. However the downside then is waste under excellent conditions when all the solar energy cannot be used. It is also less cost effective. Consider paying a lot more for an 6kW system that can maybe generate 300watts (and cover the typical background power needs under poor conditions ) but will still only generate 4kW useable under max conditions so a significant extra investment! It becomes a law of diminishing returns.

    Diverters work basically one of two ways.

    Measuring excess generation and automatically diverting that (as far as is possible) to, say, an immersion heater as an alternative to export.
    Or measuring how much generation is taking place and with a few assumptions (such as assuming the background power normally consumed) diverting to the alternative destination.

    The latter is quite simple but does not make best use of generation and might switch incorrectly when assumptions are not met. The former is generally more complicated and thus ought to be more expensive but will make better use of generating capacity.
    Usually current measurements are made with clip on sensors or estimated with some systems depending upon import and generating meter light flashes (certainly for one DIY system!). So automatic.
    We use a similar 'philosophy' manually to USE energy generated better (like most people do when they can) by trying to use high power consumption items, when it is optional, when generating solar conditions are good. Makes best use of generation and reduces paid for import.

    Paybacktimes times for investment in these additions can be 3 to 5 years, solar systems 8 to 10 years and batteries longer still.
  • pinnkspinnks Forumite
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    Hi and welcome to the forum. Soon loads of people will chip in with good advice.

    None of your questions are anywhere near stupid, so here goes...

    Re installers, and in advance of the above, take a look at https://www.yougen.co.uk - some useful info there too.

    Re batteries, the economics are just not there yet. I would love a battery but even if it provided all of my non-generating requirements (unlikely) it would save me about £250 per year at a cost of several thousand. Prices are beginning to drop but now is probably not economically viable for most of us. Having a battery-ready inverter may make sense but not my area of knowledge.

    Re going big, I would say yes but you must get approval to go above 3.6kWp. That is from your DNO (can't remember what that stands for) and takes a while. They look at the impact of your larger system on the grid. Mine was approved after a few weeks, so give yourself time. Also consider using more than one roof if you can to max out on "in direct sun" hours for each roof. E, S and W arrays would give you the absolute maximum but come of course at a price.

    Re diverters, they monitor what you are generating and what you are using and divert the rest to a resistive load (only) like immersion heater or oil-filled radiator, or underfloor heating. So, if you have 100W available that's what your device gets. If you have 3kW, then that's what it gets and so on. They are essentially clever swiches and ensure that you do not import any leccy to power the attached device. At this time of year you may need to top-up with leccy or gas in the evening, though not on a day like today! Search on here for immerSUN and iBoost and you'll find loads of threads. Mine give me all my hot water for about 8 months each year and power my underfloor heating and some radiators in the lounge in the shoulder months. Save me about £100 per year on gas.

    Take your time, ask loads more questions on here and best of luck.
    Wiltshire - 5.25kWp
    3.5kWp: 14 x Phono Solar 250 Onyx, Sunny Boy 4000TL, WSW 40 degrees, June 2013
    1.75kWp: 7 x Phono Solar 250 Onyx, Sunny Boy 1600TL, SSE 45 degrees, March 2014
  • Martyn1981Martyn1981 Forumite
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    cheeseng wrote: »
    I hope nothing here is too stupid to ask! Many thanks in advance for any advice.
    Dave

    Hiya Dave, nothing stupid in there, looks like you've done your homework.

    Batts - I'd love some, I really want some, and I'm looking and researching hard ..... but the answer is still no, not yet.

    Have a read of this thread, I think it's worth the time, for lots of ideas, angles, costs etc.

    On-grid domestic battery storage


    Cost wise, £5k for 4kWp would be nice, certainly aim for less than £6k. perhaps £1k more for 5kWp.


    Going BIG! - I would, a lot of the costs are fixed, so extra panels don't add as much as you might think.

    There are some issues, and it's worth being a bit pedantic on them. You can stick as much PV up as you like, and for the PV the term used is kWp (p for peak rating). So 16 250Wp panels = 4kWp.

    However, if the inverter can export more than 3.68kW (note kW and kWp when discussing PV) you will need prior permission from your DNO (district network operator).

    For a 4kWp system, you'll naturally have a 3.68kW inverter ... job sorted!

    For a 5kWp system south facing, an inverter capable of handling the 5kWp but capped at 3.68kW would be ok. Once hot the panels will drop to about 80% efficiency, so 5kWp = 4kW, so just a bit of capping, and the extra grunt of the bigger system might increase efficiency during poor generation times (lot of those in the UK).

    For more than 5kWp, you'd really want to ask the DNO for permission to exceed the 3.68kW limit. Probably worth asking for the 5kWp too, but not a 'deal-breaker' if they say no.


    For diverters, I don't have one, no hot water tank, but they seem to work really well, and are very popular on here, I think prices are around £250(ish) not sure.


    One other thing - there's no rush, take your time, get prices, ask and chat on here, maybe wait till late winter, early spring. You never know, maybe the government might launch some PV + storage scheme ...... one can always dream. :D
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Hi everyone,

    Thank you all for the advice!

    I like the idea of getting a system that is capable of more even if it has to be capped by the inverter to 3.68kwp so that I can get more at the max allowed. Having said that if it's not too pricey to apply to the DNO I will probably apply to that in advance quite soon.

    The diverter sounds an ideal intermediary between a straight set up and using a battery. Though how sophisticated can these diverters get? I mean I'd love to be able to divert the excess power to one thing for a while and another thing at another time (i.e. in the autumn months maybe the hot water until 3 then a heater in the front room for when we get back). But then again I guess i could do the heater with a smart plug set to go on at 3 which would then take make the diverter disengage. Hmm something for me to think about!

    As for spreading the panels over multiple roofs, I have one pretty much perfect south facing then one North facing. I do have a flat roof too, but it is massively shaded most of the day so I imagine would not be great to use.

    Thanks for the warm welcome and great advice!
    Dave
  • Martyn1981Martyn1981 Forumite
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    cheeseng wrote: »
    Hi everyone,

    Thank you all for the advice!

    I like the idea of getting a system that is capable of more even if it has to be capped by the inverter to 3.68kwp so that I can get more at the max allowed. Having said that if it's not too pricey to apply to the DNO I will probably apply to that in advance quite soon.

    Hi Dave, just to say that I contacted my DNO myself. They can't give a yes, as they have to have a formal application from a qualified electrician, but ..... if they are nice and helpful, they can have a quick check and give you a 'no' or 'not a no'. WHAT?

    Basically mine popped round had a quick look, and said, it's not a no, we would consider an application further, it wouldn't be an instant no.

    That was very helpful in moving forward for me. But it was 5yrs ago, and I suspect each DNO and each staff member may operate differently, but - you don't ask, you don't get.


    Jumping ahead here based on your mention of a heater, you might like to have a read of another thread regarding the install of a small ASHP (air source heat pump), also known as an air conditioner. Following helpful advice from others on the thread, I got one this year and it's providing most of my heating at the moment, though GCH is slowly taking up the slack.

    Discussion ... ASHP(Air/Air) with Solar pv ....

    This also takes us neatly back to batteries, as they would aid with the ASHP, hopefully allowing import free use earlier and later in the day, IF there's been enough spare generation to charge them.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Ah, that makes sense about the DNO needing proper plans and circuit diagrams before being able to respond properly thouhh I will try to sound them out like you did if they are open to a "no, not a no" scenario.

    I'll have a read of the link when I have a minute.

    cheers
  • edited 29 October 2017 at 3:53PM
    cheesengcheeseng Forumite
    8 Posts
    edited 29 October 2017 at 3:53PM
    I've just looked at the thread and I'm not entirely sure it's the best fit for me at the moment as I have a 2 year old GCH boiler installed and looking at the estimated returns on some other sites, it looks like the payback may be relatively low.

    I was just looking into PV a little more and am coming on things about 1 phase or 3 phase but I don't really understand too much - I guessed that nearly all domestic installations would be 1 phase but that is just a guess. Is this something to worry about or is it just 3 phase is for greater capacity?

    One last thing, I guess the capping on the inverter needs to be before it feeds into your house's electricity supply and can't be applied after the houeehold use but before it goes into the grid?

    cheers,
    Dave
  • Martyn1981Martyn1981 Forumite
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    cheeseng wrote: »
    I've just looked at the thread and I'm not entirely sure it's the best fit for me at the moment as I have a 2 year old GCH boiler installed and looking at the estimated returns on some other sites, it looks like the payback may be relatively low.

    I was just looking into PV a little more and am coming on things about 1 phase or 3 phase but I don't really understand too much - I guessed that nearly all domestic installations would be 1 phase but that is just a guess. Is this something to worry about or is it just 3 phase is for greater capacity?

    One last thing, I guess the capping on the inverter needs to be before it feeds into your house's electricity supply and can't be applied after the houeehold use but before it goes into the grid?

    cheers,
    Dave

    Hiya Dave, pretty much all domestic properties will be single phase, but shops and businesses that need more power will be three phase.

    So for you, it'll be single phase and 3.68kW.

    Good question about inverter/export. You are right that the inverter is capped at 3.68kW, however, there are devices etc that can cap export at 3.68kW.

    Obviously the benefit there is that household draw, hot water heater, battery charging would all come off first, so such a system would allow higher inverter output.

    As the export approaches 3.68kW, the inverter would then reduce/cap generation.

    There's also a halfway house system where the inverter still caps output at 3.68kW (AC), but directs DC generation directly to a battery first. It can then draw down the battery, via the inverter, when it's needed.

    These options are getting more complicated, and I can't remember if the export capped system has been approved by DNO's yet for domestic use, but I'm sure some DNO's have approved a larger commercial version. Here's an example.

    I might be able to find out more, but best to see what the DNO says first, as these options aren't cheap.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Hi,

    Cheers Martyn for all the advice - seems like I got a little carried away with the positioning of the inverter but it is interesting on the theoretical side!

    It seems after all that fanciful talk from me about larger systems my roof size might be letting me down! admittedly they are just estimates from Google Earth so face to face visits might yield different responses from the companies but I have one company saying i could only just fit 12 panels on, so at 300w I could get 3.6kwhp. Then I have the Ikea quote suggesting I could get 14 on the roof somehow!

    so the quotes:

    Ikea:
    14 Canadian solar 270w poly panels (with clenergy mounting system)
    solax hybrid inverter
    total:£5669

    local company:
    10x 300w(3kw) =£4,589.00
    12x 300w(3.6kw) = £4,981.00
    10x 320w(3.2kw) =£5,258.00
    12x 320w(3.84kw) =£5,721.00

    all installed with a diverter to the hot water (branded Iboost) with a solax inverter. there is no exact info on the panels except they say they would be whatever is well priced at the time but they will be teir 1

    So I'm thinking with Ikea I would have to check how much space around the panels they were leaving - it's advised to have some space for roof access isn't it? and I guess they might be a little tight. Are there any thoughts on Canadian polys?

    With the local company is the guarantee of teir 1 enough? There is the obvious benefit of having a diverter to Iboost and also both have inverters ready for battery installation.

    Is there anything I'm missing or any thoughts on the offers?

    thanks again in advance!
    Dave
  • Martyn1981Martyn1981 Forumite
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    Hiya Dave, the local prices look decent including an Iboost.

    It's interesting to see how little the extra 2 panels add in each case, about £400. Goes to show how much of the cost are fixed, then each panel, railing and labour only adds about £200 more.

    You should be able to get a rough estimate of the roof space, just measure the length of the roof from the ground, then measure the height of the roof from inside. The inside measurement will be approx correct for useable space, the ground measurement will need about 600mm subtracted.

    You can't use all roof space, rough rule of thumb, substract 300mm (200mm at a pinch) from all four sides. Top can't get too near the top slates as the ridge tiles will need removing, replacing. Sides need to avoid wind lift, and bottom needs to be short of roof lip as water will run or blow over the guttering.

    Take your roof area and divide by 1.6m2 for a rough start. In reality you'll also need 20mm between panels, and different panels will vary, some a bit bigger (or smaller) than 1.6m long, and some slightly wider than 1m.

    I think Canadian Solar are also Chinese owned. I think many/most installs tend to be whatever the installer can get at the time.

    Slight dilemma for me, I'd usually say go big, but the 300 v's 320 means £740 for 240Wp more, which isn't great, but probably fairly reflects the fact that cost per Wp creeps up with panel efficiency.

    Perhaps that £740 would be better spent on a small ASHP!

    All looking good though.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
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