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Extra arrays with awkward roof space/aspect

  • 07-08-2022 10:53am
    Registered Users Posts: 4,371 ✭✭✭

    So I've an awkward sw roof. recently got 8 panels on there, with spacing for grant probably have lost out on one panel. there is room for 2-4 additional panels maybe.

    some might have shading, ok will fit optimizers. thinking DIY most likely.


    I've a couple of questions..

    if I get inspection completed, moving the panels maybe 100mm towards roof would allow another to fit ( restricted by dormer right now. )

    has anyone done that? pm is fine

    anyone know of a panel slightly narrower than the usual 1.1m? this would get me an extra panel.

    Now to the inverter, its single string, maxed out at the current 3.3kw

    I'd want to put these new panels on an extra string, I don't really want to add another inverter, though I suppose I could? can 2 inverters share the same cable run to the fusebox? its 4mm2 cable so its not a capacity concern.

    I'm thinking to ask the installer politely if they'll upgrade it to a dual string.

    Other options that I'd like to rule in or out.

    could potentially wall mount at front of house maybe 2 panels. but this is probably against planning exemptions

    Im adding a pergola roof at rear of the house. rear faces NE this in addition to kitchen extension, but it is still significantly shaded by the house to the south. A few panels onto the pergola roof would be easy fitted but probably will do very very little in winter.

    the rear roof already has 1kw of pv, box ticking exercise onto the house when it was built. thinking the return on NE facing panels is pretty poor though.

    lastly thinking I could maybe get 2 panels onto the shed west facing, definitely would be significantly shaded by neighbours house.

    thanks to anyone who has read all that. I think after all that I'll focus on the front roof. any thoughts or anyone done anything similar?


  • Registered Users Posts: 2,228 ✭✭✭bullit_dodger

    If you don't mind doing a bit of DIY it sounds like micro-inverters are your solution. You can buy them for about €140 for 1x panel, or ~€200 for 2x panel. Run an AC cable to your roof, plug each panel into the micro-inverter and away you go. Forgive the crude drawing but conceptually it's somehting like this (assuming you were using 2x panel microinverters) , personally for the 6 panels that I have, I have 2x2 panels, and 2x1 panels, all connected daisy-chained on the same AC "string" for lack of a better word.

    Micro-inverters can be gotten from here.

    Midsummer Renewables

    but all the suppliers have them such as, Micro Inverters from TSUN ( (Albeit I haven't used those ones myself) I used the Hoymiles which have been great - cept' for the telemetry which is proving "difficult" to setup.

    I'd suggest using "armored cable" when running AC outside to your roof. 1.5mm^2, preferably 2.5mm^2 - but don't forget that you'll probably be hooking this into a circuit on your house. That circuit is (probably) limited to 16A unless your feed is taken from something heavy duty like a oven or immersion, so I wouldn't be putting more than 2.5-3Kw of panels on that circuit.

    A decent enough youtube for the enphase (they are mostly all the same) .... (539) Installing the Enphase Microinverter System (UK) - YouTube

  • Registered Users Posts: 4,371 ✭✭✭Gerry

    Thanks for the detailed reply. micro inverters would work.. possibly less than a 2kw inverter plus optimizers.

    Im wondering if they would work on the same AC circuit as the existing feed to the roof. which is 25amp, 4mm2. But I can easily run another beside it.

  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 62,713 CMod ✭✭✭✭unkel

    If you use one microinverter per panel, you don't need optimizers. And 4mm2 is ok for your AC coming from all your solar. More like 16A though (not 25A) but that translates to nearly 4kW. You don't say what panels you have but you say you have 8 panels and they total 3.3kW, so I guess about 390W each? Adding 4 would just about be ok on that cable

    And yes there are panels that are less wide than 1.1m, in fact a standard size panel traditionally is 1.65*0.99m

    Hope I answered a few of your questions

  • Registered Users Posts: 4,371 ✭✭✭Gerry

    Yeah sorry I was thinking a normal inverter plus optimizers.

    But I'll price it both ways.

    I am getting many different numbers for 4mm2 but seems to be comfortably over 20 amps.

    Panels, traditionally yep but what's on sale now seem to be all larger. thanks

  • Moderators, Education Moderators, Home & Garden Moderators Posts: 7,832 Mod ✭✭✭✭Jonathan

    The current carrying capacity of the 4mm² depends on its temperature rating and how it is installed (in insulating wall, clipped direct etc). Even worst case you're good for 20A as you say.

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  • Registered Users Posts: 4,371 ✭✭✭Gerry

    since its my thread ill tack on one more question. the installer decided that a panel would not fit landscape between top of the dormer and velux window. there is 1.45 meters available.. am I missing something? do seai rules come into play here?

  • Registered Users Posts: 4,371 ✭✭✭Gerry

    tape is not down to the dormer itself here. still 5cm away.

  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 62,713 CMod ✭✭✭✭unkel

    Yes SEAI rules state you can't go within 50cm of the top of the roof

  • Registered Users Posts: 4,371 ✭✭✭Gerry

    the rule is 200mm from the ridge, so thats not it. its the bottom of a velux window, far from the top of the roof.

  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 62,713 CMod ✭✭✭✭unkel

    Ah apologies, I misread your pic, thought that was the top of the roof.

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  • Registered Users Posts: 4,371 ✭✭✭Gerry

    yeah sorry a photo or diagram would have been better