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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorCWatters
    • CommentTimeNov 5th 2019
    I've been wondering why few schools put PV on their large roofs and it turns out the culprit is the effect that adding PV has on Business Rates...

    The Times today says...

    "The problem with business rates is that they punish investment. Putting solar panels on a roof increases a schools ratable value, a rental equivalence measure used to calculate the business rate bill. A £36,000 investment might increase ratable value by £3,600. At 50.4 percent, business rates in this case would add £1,800 a year to the schools tax bill."
    • CommentTimeNov 5th 2019 edited
    Our school is refunded all rates it is charged, so is not penalised for the PV on its roof.

    There are other inequities, though Ed Davey as DECC SoS fixed one of those for subsequent schools in the same position...


    • CommentTimeNov 5th 2019
    Posted By: DamonHDOur school is refunded all rates it is charged

    Is that particular to your school or some type of school or all schools?
    • CommentTimeNov 5th 2019 edited
    I believe that all LA-funded schools in our LA have their rates refunded like this.


    AIUI, charitable organisations get rates relief, this includes private schools, academy schools in England, nurseries, universities, etc. The rest are funded by the local authority who get paid the rates, so it's a circular exercise.

    If our kid's schools had £36k spare, they'd be obliged to spend it on fixing up the loos and the roof first, and then on something directly aligned with their educational objectives, like new teaching resources. Fitting PV as a pure financial investment is not what they are about.

    Edit: however the local authority here did have a programme of installing PV on roofs, mainly their retirement homes but also some of their schools. Don't know how the funding worked exactly.

    The point the article makes about 'tax penalising investment' is more general: if you put PV panels on the roof of your warehouse, or in a field of sheep, you have to factor the taxes and reliefs into the decision, same as any investment, if that's why you're doing it!
    • CommentTimeNov 5th 2019
    School PV is often funded by a third party, and then reduces energy bills.


    I was once told they werent allow to borrow for such capital investments even if it resulted in a profitable return.
    Dont know if thats correct.
    Id like to see a law passed making it required that all public buildings such as school, hospital , government building have PV if suitable roof space exists.

    I think the Labour party are suggesting similar.
    Yes I heard something similar, many schools are part of the public sector so can only borrow via the Government. They have lots of governance rules designed to protect public funds etc and allow the school to spend it's budget only on education, not on financial investment schemes. The ban on borrowing, extended even to the school secretary not having a credit card to buy stuff online! To be fair, that headteacher had a lifetime of experience of education but let's say, not so much at financial investments...

    An unwanted side effect is its difficult for them to borrow to invest in PV, even if the future returns looked very generous (are they at the moment?)

    The public sector has oodles of space that could have PV put on it, such as roadsides, railway embankments, military airfields, and all kinds of buildings and roofs. They need an economy-of-scale effort to install PV imho , it's taking too long when left to individual establishments and local management.
    • CommentTimeNov 6th 2019
    Posted By: WillInAberdeenThey have lots of governance rules designed to protect public funds etc and allow the school to spend it's budget only on education

    I recntly read an article how some ex-state schools were finding it hard to adjust to life as an academy because the governance and financial rules for charities were so much stiffer than for publically-run institutions :)
    • CommentTimeNov 6th 2019 edited
    I group that I am in tried hard to get PV up on public/community buildings, but did not get very far:


    I think that we should massively overbuild solar, on any available half-decent public roof. Excess production will have to be deferrable / constrainable dynamically by grid operators, but we'd then have a good solar contribution even on dull winter days. On expert I spoke to a few days ago suggested ~30% overbuild IIRC, I would suggest considering as much as 3x or 4x PV over peak summer daytime demand, and building 2:1 wind to solar.

    Then our need for solar will drastically diminish.

    I did the sums for my house, and 'enough' PV to be annual net-zero and then enough storage to come of the grid would currently cost 10x as much as doubling up my solar to be 4x over capacity year-round but only needing a few days' storage for winter.


    How much PV area might be needed?

    With no attempt to think through carefully, so probably talking nonsense, I have the following case...

    My PV generation = my grid consumption, so theoretically net zero.

    In summer my PV pretty much does all my hot water, and energy needs (of course not the little bit after sun disappears).

    July gives approx 30 times what January gives (over the month)

    So even if January ONLY needed the energy demand of July, I would still need 30 times the current PV area. I'd have thought more like 50 to 100 times net-zero area, for my house which is pretty low energy.

    Completely agree that public buildings should have PV/renewable generation. We almost HAVE to use PV on new domestic dwellings, to meet current regs. Maybe slapping tougher energy targets for non-domestic buildings would force the issue, so it's not about investing, it's about meeting gov't rules. PV can replace the expensive roof or wall cladding systems, so already getting cost offset.
    • CommentTimeNov 7th 2019 edited
    I am in London with current ~5kWp split half pointing each of east and west generating well over 3MWh/y which is about double our gross electricity consumption. In my fantasies, another ~4kpW at 70 degrees slope, pointing due south, would fill in our winter consumption with a few days' storage. I'd never be allowed to export that during summer! So for me 4:1 overbuild would suffice, but with tilt optimised for the winter part.

    What is your latitude?


    Slightly hi-jacking this thread...:shamed:

    Perthshire, Scotland, 3.8kWp giving 2.5MWh/yr

    In January, my grid consumption hits 350kWhr (for the month), but generation is below 20. So you can see the disparity.

    Conversely, in June my grid consumption is 120kWhr (for the month), but generation is over 450.

    By the way I record my day/night/generation meters every month, so have this trended over the last 6 years (sad git!!). If you don't measure, you can't improve...or something like that.
    • CommentTimeNov 7th 2019
    Posted By: GreenPaddyJuly gives approx 30 times what January gives (over the month)

    Not quite ten times here.

    I have 4 kWp south-facing in Suffolk, which generates about 3.9 MWh/a. Not quite enough to match our 4.5 MWh demand (5.3 MWh last year). No gas or other combustion here of course; everything is electric.

    Multiplying generation by ten would be OK except in Dec and sometimes Jan each year. But I'd need fifteen times (i.e. 60 kWp) to cover every month, assuming I've already seen the worst case in my records, which I doubt in fact. The reality is I've probably got enough roof space to double my existing installation if I wanted.

    These kinds of sums remind me of the time when I considered insulating a milk tanker to heat my house over the winter. I figured 20,000 litres could store enough hot water to keep us warm through winter but eventually built the house with a 250 L store that's enough for two or three days DHW.

    I don't see any point in overbuilding individual installations unless/until we've built enough to match 100% of demand in the first place. It doesn't make sense to add capacity that can't be sent to the grid (except for personal use in off-grid situations).
    • CommentAuthorRobinB
    • CommentTime1 day ago edited
    Here's an ignorant question from me but who decides business rates? Central government or local councils?

    There are plans for a new business park in my area, large south facing slope with road and river to south so unlikely to be shaded by future building. I'd love to push the council to insist all the roofs are PV, but don't really know how to set about it.

    All warehouse sheds and supermarkets should have PV roofs, and a clear incentive to do so. I've made my house uglier with PV.
    • CommentTime17 hours ago
    @djh anyone who puts in domestic solar thermal is effectively putting in significant overbuild for summer which they definitely can't export.


    RobinB, think you hit the nail on the head there.

    Business rates: the rules are set by central government, the local authority administers them

    Planning applications: the rules are set by central government, the local authority makes only the bits of policy that depend on local geography, and administers it

    Building Standards/Regs regarding energy usage: set by central government, the local authority administers it

    So even if the local authority wanted to do something creative about requiring PV or better insulation, they have to work strictly within the national rules, otherwise developers will appeal to central government to get the local authority's decision overturned.

    Unfortunately central government is further from local voters and updates the rules less frequently. The local authority's only freedom is to sneak rules into the local planning policy about only allowing 'sustainable' buildings.

    For an individual application such as the business park, the LA has to apply the rules as written, they cannot apply stricter standards to this development than to others. Best bet is to see if there's anything helpful in the local planning policy, and if not then lobby at the next update of the local policy, usually every 3-5 years.
    • CommentTime12 hours ago
    Posted By: DamonHD@djh anyone who puts in domestic solar thermal is effectively putting in significant overbuild for summer which they definitely can't export.

    I don't think I was talking about solar thermal, was I? But my attitude is that PV should be fitted instead except in cases where the available space is too restricted. It's worth noting that vertical mounting of solar heating can equalize the monthly output significantly. Oh and the various rules that encourage solar thermal are simply misguided IMHO.
    • CommentTime5 hours ago
    @Will I think in some cases it is established that the LA *can* apply structer than minimum/national standards, eg for energy, though the government would like to take that away again. (See the recent building standards consultation.)


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