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Options please - More Panels or not

  • 06-07-2023 03:46PM
    #1
    Registered Users, Registered Users 2 Posts: 1,444 ✭✭✭


    Current Setup:

    8.6Kw panels, (6Kw Solis 5G Hybrid Inverter, 30Kw Batteries - Located in House Utility) CT clamp on ESB Meter with Cat5 cable to inverter

    House and two EV's use around 1700Kwh per month

    Production & Usage:

    June 2023: Generated 1023Kwh, Exported 81Kwh, Imported 517Kwh

    May 2023: Generated 1129Kwh, Exported 30Kwh, Imported 650Kwh

    April 2023: Generated 788Kwh, Exported 70Kwh, Imported 1098Kwh


    Doubtful electricity prices will ever be as low as they were a few years ago, I can see an end to the Day and Night meter in the next few years, solar equipment seems to be getting cheaper so could probably use more solar if it were generated, problem is that I would not be able to fit any more equipment at the house as space in the utility is limited and I am also considering moving the batteries out to the shed 40m away from the house which is served by a 10sq cable from the CU in the house, I have no problem with room to ground mount panels.

    Obviously I would have to install second inverter, anyone got any ideas on if it would be worth my while and what way would I configure things ?


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Comments

  • Registered Users, Registered Users 2 Posts: 1,592 ✭✭✭DC999


    Ignoring the ‘how’ for now. Start with the ‘why’ install more. You’re still importing a lot more than you generate (fully electric house as you say). Imported ~500kwh in June and that was a belter. So that’s the ‘why’ justification. You’d be right to get more. And that all helps in the winter as could start to run some heating from electricity from solar. I did that last year in a few rooms and reduced gas heating bills.

    And you’ve space at home as you said. I think yours is the brill ground mount using telephone poles?? So you can alter the angle on a new one to get earlier or later sun than your current setup (if pure South) – if going ground mount again. On the ‘how to design’, not a clue. Others can chime in.

    We can’t bank on FIT rates of course but you’re not even exporting at the mo (only 1-kWh a day). 



  • Registered Users, Registered Users 2 Posts: 1,444 ✭✭✭Big Lar


    Well on the how is where I am stuck also to be honest.

    I can put another inverter in the shed no problem but then how can I get new inverter to communicate with original inverter to tell it that we have surplus and charge the batteries or that we are importing or exporting to the grid, the shed does not use that much electricity so a clamp on the incoming supply there is not going to help that much at all.



  • Registered Users, Registered Users 2 Posts: 901 ✭✭✭ColemanY2K


    Have you considered how you could reduce consumption thereby reducing the import?

    More panels certainly seems the obvious solution but me personally wouldn't have the technical know how.

    🌞 7.79kWp PV System. Comprised of 4.92kWp Tilting Ground Mount + 2.87kWp @ 27°, azimuth 180°, West Waterford 🌞



  • Registered Users, Registered Users 2 Posts: 2,700 ✭✭✭bullit_dodger


    8.6kwp is sizable enough. I've 8.8Kwp myself.

    How many panels are you thinking about? If it's just 2 or 4 panels, I'd go micro-inverter route. You could even plug it into a normal 3 pin socket, although I would recommend isolating the panels off on the far side of an isolation switch.

    You on a smart meter at the moment?



  • Registered Users, Registered Users 2 Posts: 3,136 ✭✭✭Buffman


    The Solis inverters can be set up to communicate with each other, so you can install as much as you want and set them up to only export the maximum allowed KW. I assume your aim is to get the import-export figures to match a lot more than currently by increasing export and reducing import.

    So an easy way to work it is to install a Solis grid-tie inverter and set them up so that your current hybrid is always keeping your large battery topped up and the grid-tie is doing most/all of the exporting.

    With the massive amount of space you have I'd be aiming to go as large as possible, if even just to cover the 2 EVs as much a possible.

    Another option to possibly consider if you want to go 'super-size' is the Mini-Generation route which lets you export upto 17kw single-phase or 72kw three-phase.

    https://www.esbnetworks.ie/new-connections/generator-connections-group/mini-generation

    The below is a general 'signature' and not part of any post:

    FYI, if you move to a 'smart' meter electricity plan, you CAN'T move back to a non-smart plan.

    You don't have to take a 'smart' meter if you don't want one, opt-out is available.

    Buy drinks in 3L or bigger plastic bottles or glass bottles or cartons to avoid the DRS fee.

    Public transport user? If you're sick of phantom ghost services on the 'official' RTI sources, check bustimes.org for actual 'real' RTI, if it's on their map it actually exists.



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  • Registered Users, Registered Users 2 Posts: 1,444 ✭✭✭Big Lar


    @bullit_dodger I would possible go another 4Kw for the time but would like the option to add on, I looked into micro inverters but not really controllable, have D/N meter at the moment and getting deemed export.

    @Buffman I would like to know how to set the inverters up to communicate with each other, I will have another challenge in that the inverters will be in separate buildings but connected to the same grid supply. I don't know about exporting 17Kw, I have an Enhanced supply I think(80A fuse) however 63A on the fuse board so I am thinking that perhaps the cabling from the meter to the board may not be adequate for 17Kw. Another option that I could probably do would be install the inverter outside and I would have a route to bring the AC cable from that to the ESB meter box if that were allowed.



  • Registered Users, Registered Users 2 Posts: 1,444 ✭✭✭Big Lar


    @ColemanY2K Cannot reduce consumption to be honest, house is going here all day, home office with a few PC's and all that goes with it, two EV's of which one does 30km per year



  • Registered Users, Registered Users 2 Posts: 1,301 ✭✭✭homingbird


    I am thinking about getting solar installed but the panel efficiency of solar panels is improving all the time no point ending up with last years old stock when this years panels are 50% more efficient that what worries me.

    https://www.youtube.com/watch?v=fFICdZ9I2wg



  • Registered Users, Registered Users 2 Posts: 1,444 ✭✭✭Big Lar


    That's a bit like waiting for next years car model, there will always be something better coming along.



  • Registered Users, Registered Users 2 Posts: 623 ✭✭✭idc


    Also not sure that efficiencies are climbing that fast if a panel that was 20% efficient then the next years panels would be about 30 but thats not the case currently. What you may of seen is panels that were 300W a few years back but now 400 or even 500+ W is the norm. The issue here is that the efficiency hasn't actually massively increased but instead the panels are just getting larger and larger. back 2-3 years ago a 300 W was approx 1.6m x 1 meter with module effiicency of 18.4 but a newer 500W panel now is 2m x 1.3m and module efficiency is only 21.



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  • Moderators, Home & Garden Moderators Posts: 7,102 Mod ✭✭✭✭graememk


    The Solis inverters dont need to communicate to export limit. You just need 1 to limit production (well if you have 2, if 3 or more.. well it depends)

    Say you set your hybrid to export a max of 6000w

    and you put in another inverter capable of 6000,

    If both are in full sun, battery is full, the hybrid will shut off/restrict its production to 0 to keep under the 6kw export limit. the other inverter doesnt know about or care of the hybrid. it just generates power.



  • Registered Users, Registered Users 2 Posts: 1,301 ✭✭✭homingbird


    So the future is panels getting smaller with higher wattage so you will be able to get more panels on your roof.



  • Registered Users, Registered Users 2 Posts: 901 ✭✭✭ColemanY2K


    Fair enough. Out of curiosity roughly how many kWh of that monthly 1700kWh figure are the cars contributing to?

    🌞 7.79kWp PV System. Comprised of 4.92kWp Tilting Ground Mount + 2.87kWp @ 27°, azimuth 180°, West Waterford 🌞



  • Registered Users, Registered Users 2 Posts: 1,444 ✭✭✭Big Lar


    Lets say I leave the House Hybrid Inverter where it is and in the shed I add a 6Kw non hybrid inverter. I set the House Inverter to 0 export and the Shed inverter to 6Kw export or something like that.

    Does the Shed inverter need to be connected to the CT clamp in the ESB meter ? If not will it only confuse the house inverter seeing export when its not exporting ?



  • Registered Users, Registered Users 2 Posts: 623 ✭✭✭idc


    Long term eventually yes, but thats not whats happening at the moment, the panels are getting larger and therefore that leads to higher wattage (with only small increases in efficiency). If efficiencys actually did improve drastically then maybe yes panel sizes might fall but at the moment panel sizes have just been getting larger -- that works for large scale ground mounted systems, but not so simple if you had to install a 2.5 x 2 meter panel on a house roof.



  • Moderators, Home & Garden Moderators Posts: 7,102 Mod ✭✭✭✭graememk


    Shed inverter doesn't need anything, let that do what it needs to do.

    House hybrid will do all the limiting by limiting itself.

    Eg before export limit

    Shed produces 5kw

    Hybrid produces 5kw

    House using 500w.


    After export limit

    Shed will keep producing 5kw

    House using 500

    Hybrid will reduce by 3500 to 1500 to maintain the 6kw export limit.



  • Registered Users, Registered Users 2 Posts: 34,152 ✭✭✭✭listermint


    I'm using around 770 kwh pm with MHRV installed and WFH and kids. Extra capacity is grand but what real consumption measures have you at hone regards to lighting and other draws



  • Registered Users, Registered Users 2 Posts: 1,444 ✭✭✭Big Lar


    At a guess both cars are about 600-700Kwh PM, that's based on my 30,000KM per year @ 16Kwh per 100km and then the wife does about 15Km a year although she is heavier on the foot would blow you out of with heat in the car so she gets like 19Kwh per 100Km.



  • Registered Users, Registered Users 2 Posts: 2,700 ✭✭✭bullit_dodger


    Another 4Kwp is 10x panels, so a string inverter would be better on that grounds. The reason I was suggesting micro-inverters was one of cost. For 2 or 4 panels, it's (usually) cheaper to buy 2x2 panel micro-inverters ~€150-200ea than to buy a string inverter. For 10 panels though, the string inverter would get the nod I think.



  • Registered Users, Registered Users 2 Posts: 1,592 ✭✭✭DC999


    If you have a Zappi you can see the stats in the My Energie Web portal or mobile app for this month, last month...Gives you a sense of historic use.

    We use 200kWh a month driving a Leaf like Miss Daisy. About 15000km a year urban driving so slow speeds. So maybe the vars use less than you think.

    It's worth a look to see if you could drop usage anywhere alright. Someone else mentioned that. Would save u buying less units on top of your existing large array. Or getting a 2nd large setup.



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  • Registered Users, Registered Users 2 Posts: 1,444 ✭✭✭Big Lar




  • Registered Users, Registered Users 2 Posts: 441 ✭✭jasgrif11


    I'm in a similar scenario. As a reminder here is my setup:

    16 X 380w panels (on main house, grant install) on a Solis Inverter - 4.9kw

    14 X 400w panels (on Garage, DIY install) on a Sofar Hyd 6000EP - 5.6kw

    10 X 405w panels (on ground mount, DIY install) on Sofar grid tied Inverter - 4.0 kw

    Total size is 14.5 kw (all 3 inverters and battery are installed in my Garage)

    I have a 40kWh DIY battery connected to the Sofar Hybrid and have all 3 inverters connected vi a MYEnergi CT Clamp.

    I use approximately 40-45kWh per day during the Winter and roughly half of that during the summer. My house is all electric. Heatpump and 2 X Evs (one is mostly charged at work).

    I have additional roof space on my house for 11 panels. This would be an East/West configuration. I originally said I was done :) but now that panel cost is coming down I'm wondering if I should max out and install the extra 11 panels. I would need to install another grid tied inverter (I have an additional consumer unit upstairs in my house) as there is no easy way to route cables back to the garage. This would also mean I wouldn't be able to add the CT clamp and route it back to my MyEnergi hub (I have 2 Hubs connected together as I also have the CT for the Zappi).

    Does anyone have a similar-sized system (50+ panels). Any advice?



  • Registered Users, Registered Users 2 Posts: 1,444 ✭✭✭Big Lar


    @jasgrif11 I am still at the planning process so the hamster is still on the wheel here and if the project was to go ahead I would be close to 50 panels.

    With regards to the CT clamp I suspect that inverters and My energy use read only from CT clamp so I am considering using existing wifi network with arduino perhaps.

    Have you considered that you could have 20Kw being generated at peak times and would the internal wiring be sufficient ? Also what would you do with the excess Solar as I have also been wondering what would I do with the excess solar if the car was not connected so would I perhaps add an additional HW cylinder to heat water for the radiators then I could circulate that around the house rather than the oil boiler firing up.



  • Registered Users, Registered Users 2 Posts: 441 ✭✭jasgrif11


    I have 3 consumer units (Main, upstairs and garage). All have 63A main fuses. I believe the wiring is fine. I'm a little concerned on the load on the consumer unit in the garage what with having 3 X 32A breakers and the Zappi breaker (should I be?).

    I'm less concerned about the excess Solar. This summer the house has been working directly off of Solar, excess tops up the battery (for off-peak usage) and charges the car. I've exported on average 300kWh to the grid for June and it will be similar for July. However, from September onwards will probably be zero export.

    I don't have a requirement for additional HW heating as my heat pump with an integrated water cylinder is very good in that regard.

    Does anyone else have 4 inverters, even those of you @graememk that are using them for load shifting?



  • Moderators, Home & Garden Moderators Posts: 7,102 Mod ✭✭✭✭graememk


    I'd be concerned about export limiting, not raise any eyebrows/drawing attention to yourself.

    As for the garage and the 3 32amp mcbs isn't a concern for me, it's more about load, it's not like there is 3 32 amp loads,

    Worst case could be:

    The straight inverter just outputs power

    Hybrid could draw 5kw, (20 amps if charging from grid)

    Zappi drawing 7kw charging overnight.

    Unless the heatpump is on that board too?



  • Registered Users, Registered Users 2, Paid Member Posts: 9,237 ✭✭✭10-10-20


    @jasgrif11, which of your inverters is your exporting inverter and are you on NC6 (ie, already maxed out in terms of the allowed kW)?

    Priority wise I presume that the primary consumers go like this: house load -> EV -> DIY battery -> grid export.

    I think you're in the almost unique and somewhat paradoxical situation in terms of Winter/Summer as I suspect that you're maxing out the export limit on quite a number of Summer days, while Winter-time you're probably unable to keep up with demand (and hence importing). So is the burning issue here the fact that you have room for 11 more panels 😉 or is it that you want to maximise your Winter generation to eliminate imports?

    If you're on NC6 and you're already swamping out the export during Summer then you already know that you're going to have to find another consumer for that excess energy; would you consider an NC7 then and go for that fourth grid-tied inverter? That should free up the Sofar Hybrid to charge-up the batteries and give you a reasonable return on the excess.



  • Registered Users, Registered Users 2, Paid Member Posts: 9,237 ✭✭✭10-10-20


    Oh and another comment : Ohm's law and the good guidance of circuit theory says that where there are multiple sources of power in a circuit (that being your overall house and garage) that the biggest consumers should be closest to the main suppliers of power and all other sources should be located further out from that point. That might sound obvious but it should be a consideration where you have a "hybrid" or "organic" electrical layout and when you're charging batteries on one inverter and potentially running a heat-pump on a nearby circuit. These would be two heavy loads which cause the largest efficiency losses as they pull power from the furthest points, or worse could in theory overload incoming circuits. In my mind the inverter with the battery should be the furthest load from the heatpump (hence with the highest line resistance) and the closest inverter to the heatpump should be the largest inverter (without a battery). That way the loads are localised to the power sources as best as possible and the line resistances are kept low.



  • Registered Users, Registered Users 2 Posts: 5,630 ✭✭✭Padre_Pio


    The general guidance is that you're better off financially when you buy many cheaper, less efficient panels than a few expensive, high efficient panels.

    Unless you're stuck for roof space.



  • Registered Users, Registered Users 2 Posts: 441 ✭✭jasgrif11


    The Heatpump is on a separate board. @10-10-20 yes the priority is as follows house load -> EV -> DIY battery -> grid export. The burning need is to limit the import in the winter, albeit I got the solar bug and only see usable space on my roof :)



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  • Registered Users, Registered Users 2, Paid Member Posts: 9,237 ✭✭✭10-10-20


    It might be a separate board, but aren't you pulling power to it from the various inverters across the house?



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