Battery - to take advantage of 2am to 5am cheap rate electricity - v2

Hi all! I have pretty much read everything in this thread and done a lot of research elsewhere too. I've decided I want to DIY some battery systems. Im thinking at least 2 x 15kwh setups, maybe more. I have a heatpump so I heat water at cheap night rate. I have no EV and dont plan on one in the near term. Currently on energia's smart data plan (11am - 8am @ 14c). Planm to change to their 4hr EV or to Pinergy 3hr EV rates. My goal is to fill the batteries during cheap EV rate, then run the house with solar & battery and dump everything back to the grid in the evening for FIT.

My solar setup and requirement is similar to ECO_Mental. 6 kwp (south facing) and and a 6 kw Solis grid tied non-hybrid inverter (NC6 form has 6 kw export). I setup home assistant and it works great for monitoring use and FIT. My daily use is actually quite low, about 10kwh/day. It appears from my research there are 3 possible routes for me to take:

1. Get a 6 kw solis hybrid (or similar 6kw hybrid). I'm limited to only 6 kw of EV rate charging (18kwh pinergy or 24 Energia). My other use during this time is very low, only HP runs for maybe 1 - 1.5hr @ 1.5-2kw max. This seems like a waste and limits the battery size I can get use out of. Although 2 x 15kwh system would be sufficient here (18 - 24kwh charging.
2. Get an inverter that can be limited to 6kw feed in on the grid side but can charge the battery >6kw (maybe something that can charge batteries up to 10kw. This seems like the most straghforward from implementation & control standpoint. Thoughs here? Is this not possible or practical? Whats the best indverter to go with as I need a new one?
3. Standard 6kw hybrid (solis or other) and supplement charging with rectifiers. This is my least preferred option.

Please any help from the experts here would be great. To me option 2 sounds the most ideal?

@Abromavich didnt realise that Energia and Pinergy had a limit on their EV rates!!

1. "… I'm limited to only 6 kw of EV rate charging (18kwh pinergy or 24 Energia). "

Heres me pulling 10-15 kW for three hours a couple of nights ago at 6.33cent a kWh (Bord Gais)…it gives me great sadisfaction doing this😎 all I need to add is another 5-6 kW of battery charging on to this. It will be tight!

I think that poster was considering a situation where they only had a 6kW inverter to charge the batteries rather than an electricity supplier imposed limit.

After a good bit of thought I think I have settled on the Energia for the first year. Its is very similar to the "smart data" plan but they said they cannot offer me this exact plan without an active metre but its just a 0.9 cent higher on the night rate which isn't terrible.

It is 27.6 cent peak, 26.33 day and 15.03 night which I think is a reasonable compromise of low night rate and not an insane day/peak rate until we get a feel for our usage and can properly compare next year our usage patterns vs all plans. They also have one of the highest FIT rates at 0.24 cent (if it lasts) and pay by bill cycle. So all in I think a good option for year 1.

Have one of the 15kWh GobelPower batteries in its way from China that I paid €2300 for, just ordered an ex-EU stock one this morning for €1723 - too good a deal to pass up!

https://www.gobelpower.com/gobel-power-gpsr1pc200-standard-512v-280ah-15kwh-lifepo4-server-rack-battery_p199.html

Where can I get cables to connect to a solis inverter?

hi,

I’ve had a look at bonkers etc and it seems to be difficult to find this info -

Are very low EV rates (8%) available anywhere any more? We had this rate with Energia last year and I hadn’t that our night rate had come right up with a switch we made (18%).

I’m looking at investing in solar and battery and the higher night rate isn’t making the business case look great

Would appreciate any insights you can provide.

Thanks,

David.

Finally got all of the components and built the battery yesterday without any major hassle.

That said, I am having an issue getting the battery and inverter (SAJ H1) to communicate. The supplied CAN cable is too short so I am using a Cat6 Ethernet cable as a substitute. None of the available protocols in the JK BMS app seem to work. Is the issue likely with the cable or do I need to program the JK BMS via a PC before it can communicate with the inverter?

After seeing the latest Fogstar offer I'm thinking once more about the battery option.

Looking at my winter usage I reckon a 15/16kWh battery would reduce my annual bill to zero when FIT is taken into account. Even if FIT dropped to 10 cents or less I worked out I could still break even if I exported a certain amount of residual power to the grid from the battery (maxing out the €800 tax free allowance from FIT - 2 people in the bill). Pay back in 4 to 5 years as things stand.

My only concern is the 8kW heat pump. I've looked at the settings and don't think it can be programmed to heat the 180 litre tank during the short EV period BG have - maybe it can but I'll need to take a deeper dive into the installation settings. It currently tops up the temperature to 50 degrees when it drops to 40.

Another concern is whether the HP can run off the battery given the X number of kW needed. It rarely works at full tilt, in fact during the coldest spell it was using about 1kW per hour on average in a 24hr period. The average usage in November was 8kWh in total in a 24hr period (0.3kWh).

Appreciate some advice on the technicals as the maths are heavily reliant on running the bulk of the house off the cheap EV rate.

I also have a Samsung 8kw heat pump. The maximum load it pulls out is 3.2kw and it only happens when this is <0Cº outside, which doesn't happen too often in Ireland. Most of the times it will pull no more than 2.5kw.

I am able to heat the full water tank (260L) in about 45min only, starting at 2am. I only need to heat water again in the evening (17:30) and I have hot water all day long (4 people in total).
The HP will only get the water to ~50ºC, but you can go over it (up to 75ºC) with the immersion heater running alongside. You can do it by setting the disinfection feature to run every day if you want, and it is likely you won't need to heat a second time in the evenings, consuming battery charge.

Wether you can run the house entirely from the battery is a matter of battery size + inverter capacity.

That's good to hear. I might try that with the immersion and see what it does to consumption. It is currently set to come on once a week, late on a Saturday night.

I have a CT clamp on the heat pump but there's no way of knowing (without going to the screen on the cylinder) whether it's coming on to heat the tank or heat the water in the UFH pipes. By setting the immersion to come on at a set time will help identifying what is what.

My HP is a thermia. I'll see later on what settings can be changed. I'll be curious to see what it does to overall usage.

I got 14 panels installed yesterday, and Solis 5kW inverter and (laughable with hindsight) 5kWh Dyness battery.

Had to laugh watching the SolisCloud today - we have already consumed 17kWh of energy by 6pm. That is despite the gas central heating and gas inset stove, and we haven't even charged the car today. The ESB hdf files averaged 10kWh usage per day over last 12 months - Clearly winter weekend days heading towards Christmas is way way out from that.

On the plus side, 3kWh was produced by the panels and entirely devoured up by the house. It's not much, but it's something. Also E/W orientation panels - sigh!

I guess next step is to switch to some smart EV tariff and add another 10 kWh of battery (in the attic… ouch)? I will start reading this thread from start to pick up some ideas. Any pitfalls trying to add DIY battery to a brand new solar install (warranty?), or should I just get the same crowd to install another 5kWh Dyness?