Where do I start?

[Moxi]

Hi Beau,

The door insulation just needs to be to a standard that you and the wife are happy to look at through the colder months, I think Biffs was literally a sheet of celotex cut for a snug fit and held to the door with series of bungee's - its a shame hes not on here to advise. In the warmer months this insulation can be put in store and the doors re-used to suit.

Sounds like a lot of people on here where general loads and consumption is under control and monitored to a greater or lesser degree so I would think the next move would be some consumption monitoring at different parts of the day and over night to see when your larger day time loads occur and what your overnight quiescent load is.

You can then invest in some smart plugs if you think its beneficial and schedule some over night loads to be turned off from x hour at night until Y hour in the morning to kill any standby loads.

Once you have all that you will know what size battery you need to get you through a night, once you have that you can decide how many nights you want to load match with batteries to tell you how many batteries you need and then when you have that figure you can look at your existing solar and determine if you have enough day time solar to run the house and charge the batteries.

once you have all of that then just look back at your figures and apply some winter solar production and see how it still looks, this should identify roughly the months where you are going to be buying grid electric - thats when you can look at the east west solar edge type ground mount to see how that changes the likely charging profile / battery size - panels being cheaper than batteries you may opt for more solar and let some power be lost to heat in the better months (a bit like letting solar thermal stagnate but without the concerns).

as an example we use around 7kWh per day in winter and 1kWh in high summer, 2kWh per night consistently, so I bought 14kWh of batteries working on the basis that from April to October I would have enough to run the house through the day on solar with battery input for peak loads (kettle etc) and still have enough power to recharge the battery for the evening and night time loads - my array faces west so my bulk power comes in from 1pm till 4pm in March/ April where I routinely see 2 to 3kWp. To help this I have a mobile 540Wp south facing array to get some earlier power for the batteries to help the charge out - On a run of bad weather I will buy daytime power and use the batteries for the quiescent load only as this is nicer for the batteries and inverter operationally and gives me longer for a good day or two of brighter weather to bring up the SoC.

Well thats the theory once I get it all up and running I will be able to say if its sufficient or not - i have space in the rack for another 7kWh of batteries if needed, but thats how i would approach your current conundrum.

Moxi

[Gareth J]

Do you use a "diverter" type gadget that sends any unused solar generation into a hot water tank (or any resistive load)? iBoost, Solic200, immersun, Eddi etc

If your usage is fairly low, you should be able to meet all your summer hot water needs.

Another option would be to employ one of the more customisable monitoring boxes (Eddi?)to control you gshp, so, if generation, or export, exceeds a certain amount, the gshp fires, maximising the heat you collect when the electric is free.

[Beau]

No diverter at present

Can I just buy a kit like this to start with and get a sparky to wire it up or is all far more complicated than that?
Spoke with our FIT provider and all they want is a schematic of the wiring to check they are happy with it all but no idea what other hoops need jumping through

https://www.itstechnologies.shop/collec ... -2-392-vat

[Moxi]

Yes Beau thats the kit a few of us have bought and get an electrician to wire up for you, the FIT people do not need to know about the install but the DNO does and they need to sign off on the install. You may be using FIT in place of DNO but they are different.

Its quite straight forward - that said mine still not finished! but thats because I am pratting around and getting distracted.

Moxi

[Beau]

Thanks again Moxi

" that said mine still not finished! but thats because I am pratting around and getting distracted"

That's a good description of much of life



No, not muddling the two just picked up some wrong info along the way.

Thought the DNO was only interested if I increased my PV above 3.68 kWh. I have got a request in with Western Power to see if I can export more and what 3 phase might cost. Suspect 3 phase will be a small fortune but it would so handy on the farm and for my logs business so worth an ask.

Back to that battery bank would it be possible to add more PV to it in the future if it's set up on the existing FIT tied system now? Got a sparky that is happy to do the work as long as I sort the kit

[marshman]

Leave the existing FiT PV system alone - then there is no chance of losing the FiT payment. The "kit" you linked to just has a Hybrid inverter charger - so will manage the batteries for you, charging either from just excess PV generation from your existing FiT system or in addition you can get it to charge from off peak grid as well.

If you spend a bit more on the inverter you can get one that does all of the above but in addition has a couple of MPPT inputs for you to connect more panels to.

As Moxi says there is no need to get your FiTs provider involved as you are not touching the FiTs system.

The DNO does need to know as you are connecting more "generation", i.e. another inverter which could add another 3.68kW (or what ever it is rated at) on top of whatever your existing PV system can generate.

If both your existing PV AND the new battery storage inverter are 3.68kW or below (i.e. max of 3.68kW existing PV AND max 3.68kW batter inverter) then you can use the "Fast Track" G99 "lite" application and make sure the new inverter is G100 compliant and will export limit down to 0. BUT if you get a hybrid inverter for the batteries that will also have PV connected then you have to do a full G99 A1 application - to be honest it is not a lot more difficult, I think it is a case of the regulations not keeping up with technology.

Another way would be to get the kit you highlighted, sticking to the 3.68kW limit and use the fast track process, then connect any additional PV via a charge controller and charge the batteries directly. That requires more "boxes" and can be more difficult to integrate but does have the advantage of the DNO not being bothered by the PV bit.

[Joeboy]

Hi Beau,

The door insulation just needs to be to a standard that you and the wife are happy to look at through the colder months, I think Biffs was literally a sheet of celotex cut for a snug fit and held to the door with series of bungee's - its a shame hes not on here to advise. In the warmer months this insulation can be put in store and the doors re-used to suit.

Sounds like a lot of people on here where general loads and consumption is under control and monitored to a greater or lesser degree so I would think the next move would be some consumption monitoring at different parts of the day and over night to see when your larger day time loads occur and what your overnight quiescent load is.

You can then invest in some smart plugs if you think its beneficial and schedule some over night loads to be turned off from x hour at night until Y hour in the morning to kill any standby loads.

Once you have all that you will know what size battery you need to get you through a night, once you have that you can decide how many nights you want to load match with batteries to tell you how many batteries you need and then when you have that figure you can look at your existing solar and determine if you have enough day time solar to run the house and charge the batteries.

once you have all of that then just look back at your figures and apply some winter solar production and see how it still looks, this should identify roughly the months where you are going to be buying grid electric - thats when you can look at the east west solar edge type ground mount to see how that changes the likely charging profile / battery size - panels being cheaper than batteries you may opt for more solar and let some power be lost to heat in the better months (a bit like letting solar thermal stagnate but without the concerns).

as an example we use around 7kWh per day in winter and 1kWh in high summer, 2kWh per night consistently, so I bought 14kWh of batteries working on the basis that from April to October I would have enough to run the house through the day on solar with battery input for peak loads (kettle etc) and still have enough power to recharge the battery for the evening and night time loads - my array faces west so my bulk power comes in from 1pm till 4pm in March/ April where I routinely see 2 to 3kWp. To help this I have a mobile 540Wp south facing array to get some earlier power for the batteries to help the charge out - On a run of bad weather I will buy daytime power and use the batteries for the quiescent load only as this is nicer for the batteries and inverter operationally and gives me longer for a good day or two of brighter weather to bring up the SoC.

Well thats the theory once I get it all up and running I will be able to say if its sufficient or not - i have space in the rack for another 7kWh of batteries if needed, but thats how i would approach your current conundrum.

Moxi

We added a load of under engineered flooring insulation boards to the garage side of a home to garage internal door. 6 boards deep I think, held in place with black duct tape. Looks quite good and certainly does the job.

[Beau]

Hi again

Just heard back from a local installer who has come back with what I see as a reasonable fitted price.

Does anyone have any views on Victron batteries and inverters?

Thanks

[Stinsy]

Victron kit is high end and reliable. It is expensive though and can be complicated. Victron like to sell you a handful of devices whereas other brands make all-in-one hybrid inverters.

Victron batteries are lead-acid (unless I’ve missed them launching LiFePO4). Lead is last-century technology with a lot of reasons to avoid (short lifespan, low efficiency, shallow discharge depth).

[sharpener]

Have just installed Victron MultiPlus II-GX 48/5000 and 7.1kWh of Pylontech Force-L2. Have had to de-rate inverter to 3.7 kW to keep DNO happy. 3.68 kW of pre-existing PV is on AC out so will stay working if grid fails.

Victron inverter v. robustly made but fan noise above 1kW output is a bit agricultural. Supplies whole house thanks to 50A passthrough, don't think you could do that with Solis 3.0 kW kit. Mode changes from charge/discharge/grid failure are imperceptible. Remote access full of features.

Pylontechs will not supply full current below 20 or 25% SoC which is disappointing, is a limitation of their BMS, am looking to write a software fix in the Victron.

Victron own brand LiFePO4 12V batteries exist but are mainly aimed at the boat/RV market, not really intended for domestic ESS and expensive.


HTH