Hybrid inverter or AC coupled on Solar/Home Battery system

ispookie666

Just to add to the confusion - I have enphase micro inverters.  6.6KWp(20 panel) system split across 4 different orientation/roof and have a 3.5KW Givenergy AC coupled inverter (Givenergy battery are on back order).  I was surprised by the DNO approval as the maximum theoretical generation would be 10.1KW!  Realistically, i'm yet to see peak solar production above 4.1KW.  

On another note, 8.2KWh battery are no longer being sold by Givenergy(unless you have them on order) and are being replaced with 9.5KWh.  

QrizB

bewidds said:

That said I am also looking to electrify my house gradually, i.e. install German style electric radiators instead of a gas boiler. My current annual usage is about 4,000KWH, but i expect this to increase.

Unless you want crippling electricity bills, don't install electric radiators, "German style" or otherwise. Mains gas is still the cheapest option but if you want to reduce your carbon footprint a heat pump is a much better choice than direct electric heating.

See this post (and indeed the whole thread) if you're in any doubt about that.

94JDH

bewidds said:

Thanks for all these comments. I am in a similar position as the original poster. Considering a 4,130 kw array with possible the 8.2kw Givenergy battery. From what I am reading above a battery doesn't make loads of sense, although I was wondering if the energy price hikes make much of a difference to the equation.

I am considering getting a EV within 12-24 months, so it seems like the battery may well become redundant.

That said I am also looking to electrify my house gradually, i.e. install German style electric radiators instead of a gas boiler. My current annual usage is about 4,000KWH, but i expect this to increase.

Any advice or does the above advice still hold for now?

If you're going to see a increase a battery will be useful and you can also top up the charge on it during night time if you have a low off peak rate like Octopus Go or EDF Go electric. 

bewidds

QrizB said:

bewidds said:

That said I am also looking to electrify my house gradually, i.e. install German style electric radiators instead of a gas boiler. My current annual usage is about 4,000KWH, but i expect this to increase.

Unless you want crippling electricity bills, don't install electric radiators, "German style" or otherwise. Mains gas is still the cheapest option but if you want to reduce your carbon footprint a heat pump is a much better choice than direct electric heating.

See this post (and indeed the whole thread) if you're in any doubt about that.

Thank for this point QrizB, it's made me pause. The thinking was that if I am generating my own electricity then it can be used for electric radiators. Perhaps there will not be enough power generated though...?

All the advice on heat pump seems to be that in order to be effective you have to fit new (larger) hot water pipes and larger radiators, so the installation cost is huge. A friend who has had one installed (without getting new radiators) says it's terrible and their energy bills are huge.

Has anyone ever made use of an independent expert to asses your own specific situation? There are so many variables!

QrizB

bewidds said:

QrizB said:

bewidds said:

That said I am also looking to electrify my house gradually, i.e. install German style electric radiators instead of a gas boiler. My current annual usage is about 4,000KWH, but i expect this to increase.

Unless you want crippling electricity bills, don't install electric radiators, "German style" or otherwise. Mains gas is still the cheapest option but if you want to reduce your carbon footprint a heat pump is a much better choice than direct electric heating.

See this post (and indeed the whole thread) if you're in any doubt about that.

Thank for this point QrizB, it's made me pause. The thinking was that if I am generating my own electricity then it can be used for electric radiators. Perhaps there will not be enough power generated though...?

The problem is, you want heat in the winter, when it's cold and the sun doesn't shine much.

I've got a relatively small solar array - only 2.72kWp - but last December it only produced 41kWh. Our average gas consumption was over 30kWh/day, so my array would have had to have been 25x as big to get us through the winter. And 70kWp isn't a credible home installation (it would cost around £70,000m for a start).

You can see details of my electricity generation and consumption through the year here (no gas info yet, sorry):
https://forums.moneysavingexpert.com/discussion/comment/79100930/#Comment_79100930

bewidds said:

All the advice on heat pump seems to be that in order to be effective you have to fit new (larger) hot water pipes and larger radiators, so the installation cost is huge. A friend who has had one installed (without getting new radiators) says it's terrible and their energy bills are huge.

Yes you are likely to need new radiators but compared to direct electric heating it will pay for itself in time. It sounds as though your friend's system was poorly specified (or perhaps they didn't agree to all the recommended changes).

Reed_Richards has replaced his oil boiler (roughly half the price to run vs. direct electric heating) with a heat pump and so far it's working out to cost a similar amount as oil did. You can read his thread here:
https://forums.moneysavingexpert.com/discussion/6240076/i-bought-a-heat-pump

bewidds

Would it change the equation if I went for the battery and used the Octopus Go tariff to charge it up at night (during the winter) then used that for an electric radiator (plus everything else).

(Not trying to be argumentative btw, just thinking it all through and valuing the advice. Thank you!) 

Solarchaser

You can go with batteries and charging, several of us already do that, however if you look at your dead of winter heat consumption you will likely find that to replace that with useable battery consumption would be 30k plus.

It's something I'm really looking into just now.
My gas has tripled in the last year,  but the octopus go faster rate hasn't.
I believe on octopus go faster you can provide enough heat to *something* to then use it for heat during the day and be cost neutral with gas.

The problem is the something. 
There's sunamp, (phase change) and there is warmstone from caldera, (hesting stone to 500c) there is also tepeo in Winnersh (heating concrete to 500c)which all offer a possible solution.
Sunamp is max 12kwh, not enough for me.
Tepeo is 40kwh, maybe enough for me, but too far away to be considered at the moment, if you are near Reading, maybe a possibility for you
Warmstone is 100kwh, this would be great, but its 1.7Tons and £12k and I really don't think I can justify it... but by golly I'm trying.

If you have the room, a large water tank and plate heat exchanger would do it, and insulate the heck out of it, but I don't really have the room.
In the loft is a possible solution,  but thats alot of weight to have up high, and you might find that 1st floor is 15mm piping and ground floor is 22mm, so pushing heat down from above may mostly circulate on 1st floor rather than the ground floor where its most needed.