Solar Application Rejected by District Network Operator

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digbydog
digbydog Posts: 32 Forumite
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I was going to have a solar panel installation of 20 panels each with a potential generating capacity of 295w giving a total potential capacity of 5.9kWp. The estimated actual annual output was going to be 4,795kWh.

However my application to the DNO has been rejected, don't know why.

I understand now that if I want to go ahead,I have to reduce the output of the system to a level which does not need approval. I believe that this is 3.68kW and that I can achieve this in one of two ways:
  • Reduce the number of panels.
  • Limit the output of the system. I'm not sure if this is done pre-onsite usage or post-onsite usage, i.e. does this include any electricity usage in the house.

I guess I can do a little of both, reduce the number of panels, to say 16, and then limit the output.

Any wise comments? I kind of think any limiting will be done by the inverted and so will be before any onsite usage.

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  • michaels
    michaels Posts: 28,008 Forumite
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    digbydog wrote: »
    I was going to have a solar panel installation of 20 panels each with a potential generating capacity of 295w giving a total potential capacity of 5.9kWp. The estimated actual annual output was going to be 4,795kWh.

    However my application to the DNO has been rejected, don't know why.

    I understand now that if I want to go ahead,I have to reduce the output of the system to a level which does not need approval. I believe that this is 3.68kW and that I can achieve this in one of two ways:
    • Reduce the number of panels.
    • Limit the output of the system. I'm not sure if this is done pre-onsite usage or post-onsite usage, i.e. does this include any electricity usage in the house.

    I guess I can do a little of both, reduce the number of panels, to say 16, and then limit the output.

    Any wise comments? I kind of think any limiting will be done by the inverted and so will be before any onsite usage.
    Not sure of your setup obviously but one option might be to have half thenpanles face E and half W then the 3.68 invertor limit will only lose you a few percent at midday but you will still make most of the output from all the panels.

    Not sure if there are any pre-invertor storage solutions that could soak up any generation above the dno limit and release it back when generation is lower.
    I think....
  • Martyn1981
    Martyn1981 Posts: 14,766 Forumite
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    digbydog wrote: »
    Any wise comments? I kind of think any limiting will be done by the inverted and so will be before any onsite usage.

    Not necessarily wise, but I can think of a few things.

    First as Michaels asks, is all the PV on the same orientation, if not, then it won't matter too much.

    Secondly, you can limit the inverter to 3.68kW, regardless of PV system size. Yes you'll lose a bit on a 5.9kWp south facing system, but probably less than you think. Long time back I saw estimations (not actual results) of a 8kWp south facing system losing 20% pa.

    Thirdly, Google Emma GVS, here's a link, but just the first I read. You'll need to do homework and see if your DNO accepts them, but possibly/probably not and that's if there's a domestic version available, I'm not sure. They limit export to 3.68kW, not generation, so the inverter degrades output only as export goes high, rather than generation. So it'll deduct baseload, household items, water heating, battery charging etc.

    Fourthly, a DC side battery install. Probably a bit too expensive at the moment, but this would allow (purely a made up example) say 5.68kW generation, with 2kW going into the batts and 3.68kW going into the house.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW). Two A2A units for cleaner heating.

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • pile-o-stone
    pile-o-stone Posts: 396 Forumite
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    Did the DNO reject your application out of hand, or did they say you had to pay a fee to strengthen the existing network? We have just installed a further 1.8kw and at first the DNO was talking about levying a substantial fee, but in the end they approved a zero cost submission. We've now just asked for a further 3kw and we are 2 weeks into the (upto) 6 weeks approval process. We're not expecting to have the full 3kw approved, but will ask what the maximum zero cost generation they will allow.

    We will then probably take the route that Mart has advised, limit the output via the inverter and install a DC battery system so that we still get the full solar panel generation, but have it spaced out over a longer period.
    5.18 kWp PV systems (3.68 E/W & 1.5 E).
    Solar iBoost+ to two immersion heaters on 300L thermal store.
    Vegan household with 100% composted food waste
    Mini orchard planted and vegetable allotment created.
  • digbydog
    digbydog Posts: 32 Forumite
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    I'm one removed from the DNO as the installer, EON Solar, is dealing with them. EON says that the application was rejected with no reason given, I got the impression that this was the norm.

    The current wife says I'm only allowed to use the back of the house for the solar panels as they are too ugly to put facing the street(!). So the battery option suggested by Mart seems to be the most likely option. I've put this to EON who says that they will produce some figures about how much of a difference a limited system will make in real life i.e. how many days would the system exceed the limited amount. They say that even if I go with the battery option and they limit the system they will still have to make a new application to the DNO.

    Pile-o-Stone, did you deal with the DNO directly and if so how were you able to challenge their original decision?
  • ard123en
    ard123en Posts: 265 Forumite
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    Is it that you can't have more than 4kWh on grid ?
    Could you split it and have the other 2kWh on a separate non grid tie that way could have power during grid outage
  • ard123en
    ard123en Posts: 265 Forumite
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    Or limit the system so even on a dull days you get nearer the 4kWh
  • NineDeuce
    NineDeuce Posts: 997 Forumite
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    It is almost certainly due to the demand on the grid. There isnt really a way round it. The grid has an obligation to manage this and is common place to restrict levels of generation from one station, particularly given the increase in micro-generation over the past few years.
  • digbydog
    digbydog Posts: 32 Forumite
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    Thanks for all your replies.

    EON Solar, my installer, has come back to me with their best estimate of the cost impact of reducing the amount exported and it was less than £5 per year. They intend to fit some 'widget' that means that the house will still have the full use of the panels but any export will be limited. My understanding, still to be confirmed, is that the cost of the widget is not significant and they would cover that cost.

    The only downside is that another application needs to be made to the DNO that promises that the 3.68kW limited will not be exceeded. This means that I will probably miss this quarter when being allocated to the FIT scheme.

    There are a few comments on this forum about dubious Solar salespeople. I would like to say I've been pleased with EON and felt I was talking to people who were not just out to sell a system. However, I doubt they are the cheapest.
  • pile-o-stone
    pile-o-stone Posts: 396 Forumite
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    digbydog wrote: »
    Pile-o-Stone, did you deal with the DNO directly and if so how were you able to challenge their original decision?

    I went through an installer, but one who seems to have a good relationship with the local DNO. The £1500 charge was a 'finger in the air' response from the DNO to the initial submission, but at the end of the formal application, they decided on zero cost. The installer did report back that the DNO were a bit undecided through the approval process and doesn't think they will approve our recent 3kw submission. If refused, my supplier will haggle with them about what level of output they will allow for zero cost (or low cost).

    I'll probably end up fitting 3kw of panels anyway and an inverter that is limited to the output they will approve, then fit a DC battery to store the excess for later use.

    I really like the growatt DC battieries (SP2000) and they're reasonably priced.
    5.18 kWp PV systems (3.68 E/W & 1.5 E).
    Solar iBoost+ to two immersion heaters on 300L thermal store.
    Vegan household with 100% composted food waste
    Mini orchard planted and vegetable allotment created.
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