Domestic 3-Phase Upgrade Costs

cros13 · 01-06-2023 1:01am #1

I'm in the process of buying a new house and my plans include quite a lot of existing electrical loads (from an 11kW (peak) induction cooktop to a air source heat pump (it appears to be a panasonic bi-bloc, at least 9kW)), my computers (which I can run on three phase PDUs) and I plan a large solar install (over 13kWp DC). My family are also long term EV owners (nearly 10 years) and basically all my family and friends are EV owners.

The plan is to install four load balancing capable, 22kW capable EV chargepoints off a single (these are Tesla Wall connectors and can be switched from single phase to three phase and load balanced in software, I can just set the amperage I want it to share and they share power and prioritize vehicles automatically). All of my immediate family's vehicles are capable of at least 11kW 3-phase AC charging.

So the plan is to upgrade the 100A/16kVA existing supply in the house to 29kVA/3-phase. I'll be replacing the CU with a larger unit. House is in an Urban area with nearby three phase.

I know ESB has a network charge for this for new connections of €5366 + MV charges of €24.80/meter for underground cable + trenching. Is this likely to be charged in full for upgrade or is there usually some kind of discount? Is there any change to standing charges? Any suggestions for how to balance loads?

Ubbquittious · 01-06-2023 3:10am

Post some pics of your set up if you ever get it in, sounds like an insane setup to have. Are you hoping to whore these EV chargers out to the general public to make a few bob?

cros13 · 01-06-2023 10:12am

https://www.boards.ie/discussion/comment/120664659#Comment_120664659

Not quite! Part of the point of the 3-phase charging is to be able to mostly charge the cars during whatever low rate period exists (like the 3 hour super low rates you can get on smart meter plans between 02:00 and 05:00 at night, as low as 6.5c/kWh on some plans). My current home has an MCC02 day/night meter with 9 hours of off-peak, but ESB are no longer installing those.

I will be fitting a home battery as well. At least 24kWh to try to eliminate any power draw from the grid beyond EV charging for 6-9 months of the year. I'd love to go with micro-inverters and an AC battery solution that I can easily expand. But finding it difficult to design, especially since a lot of suitable parts for that kind of solution are just not available or not approved for grid connection in Ireland. My backup plan is a SolarEdge SE10K-RWS Hybrid Inverter, the ~13kWp of solar panels and a BYD Battery-Box Premium LVS 24kWh home battery (all parts that are easily available and approved in Ireland). I've budgeted €30k ex. VAT for the Solar/Charging. I have the chargepoints and some 5x6sqmm SWA cable already and I can do some of the work myself, going to purchase the panels by the pallet myself (I have another property I'll be doing later that I can use any spare panel with). Just kinda wondering what impact on my budget the ESB charges are going to be.

Ubbquittious · 01-06-2023 2:46pm

If you spend 30k on this will you ever see it back? I think the standing charges are saucy enough, a lad who had it told me something like 90e per month but that was before all the increases. Would you not be better off running your whole house off a massive 3 phase inverter and just use the existing grid connection to charge the battery? If you are going down the road of trying to use as little as possible from the grid but you spend loads to massively increase your import capacity then your cost per kwh drawn from the grid will be sky high. I am not even sure if those 2 to 5 tariffs are available if you get 3 phase, you will need to find that out first

cros13 · 01-06-2023 5:53pm

Not really doing it for RoI. I got my dad's 6.3kWp solar for €5.5k. Cheap chinese panels and string inverter, no battery and an immersion diverter. His RoI was just over 3 years. Would have been 4-5 years without the export tariff and recent rate increases.

Off-grid three-phase is just not practically possible. The max sustained output of that BYD battery for example is only 5kW. it's just to time shift solar production to cover peak/day electricity demand from domestic loads until the night rate kicks in. And with the bonus of keeping the freezer running during power cuts. It's also a waste to cycle those batteries with anything but power I'm getting for free or close to it.

I'm doing this like this because I can and I have an interest. Expensive high end panels, microinverters/DC optimizers, large home batteries and three-phase are all things I'm doing for efficiency/flexibility/capability not RoI. I will see it back long term, my non-EV domestic power consumption is 12,000kWh which even with the influence of night rate and discounts is nearly €4k/year excl. standing charges. This solar install should produce around 11,000kWh/annum on average. With 24-40 kWh of home storage and over 200kWh of battery in the cars it's unlikely we'll even export a single unit outside of the most exceptional days of summer. Once you start adding all the EV charging and a much larger house it's even possible I might hit 25,000kWh in future years. And ESB won't let me grid connect any microgeneration above 6kW without 3-phase.

Much of our current EV charging is at work/gym where in both cases we get 22kW three-phase charging for free. But that won't last forever, and here's my own car for example (it's been a low mileage year):

Domestic 3-Phase Upgrade Costs

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