Green Building Forum - Help me pick a grid tied home battery, please

Help me pick a grid tied home battery, please

revor — Wed, 17 Aug 2022 08:18:26 +0100

Posted By: qeiplI have just created a power cut by turning off the grid at the consumer unit and am now running on battery power and a solar array that's connected to the battery via a Victron MPPT charge controller. There was no loss of power when I flicked the switch.

Do you mean at the consumer unit or at the incoming grid isolation switch.
I would be interested if you could draw a schematic of the layout.
Presume you have a secondary privilege loads CU connected to you inverter as due to load to put your full main CU on battery could be an overload situation? My system is wired up to run off battery in event of power cut but have yet to complete the settings on the inverter. My system there would l be a short delay of up to a minute or more before battery only comes on stream. As yet have not felt the urgency to complete the install as our power cuts are very small of a few seconds only. I had heard the Victron was a system that does switch over without interruption to supply so am interested to learn more, as if my inverter was to break down I would consider replacing with victron.

Help me pick a grid tied home battery, please

andrew_rigamonti — Wed, 17 Aug 2022 08:38:48 +0100

I am waiting until the link between EV cars and home batteries is mainstream (V2X).

Old Nissan Leaf's are still round Â£6K and retain over 20KWH of battery. As a second car it sits around most of the time and would be an ideal battery source. Sadly I now have a Kia, very nice but the US power system doesn't allow bi-directional use.

EVs are still quite new tech as is battery storage. In 5 years I am sure a combined setup will be more standard and reduce overall install cost as well as be more practical.

Help me pick a grid tied home battery, please

revor — Wed, 17 Aug 2022 13:22:55 +0100

Posted By: andrew_rigamontiSadly I now have a Kia,

I believe that the Kia EV 6 is V2L (load) and will allow up to 3.6 Kw to be plugged in via its adapter so one could plug in a house appliance via an extension lead.
Guess next development would be 2W connection to the house via the home charger aka the V2G being trialled.

Help me pick a grid tied home battery, please

Peter_in_Hungary — Wed, 17 Aug 2022 13:59:56 +0100

Posted By: revorI believe that the Kia EV 6 is V2L (load) and will allow up to 3.6 Kw to be plugged in via its adapter so one could plug in a house appliance via an extension lead.

The kia niro ev (thats the 'cheap(er)' one) also has V2L.

Help me pick a grid tied home battery, please

andrew_rigamonti — Thu, 18 Aug 2022 09:28:14 +0100

Yes V2L but not V2X, a full 6.6KW link (or more with 2 phase) becomes more usable as its in line with solar output and the charger cable etc is rated to that already.

Help me pick a grid tied home battery, please

Doubting_Thomas — Thu, 18 Aug 2022 11:46:35 +0100

@qeipl
"I installed 10kWh of Pylontec batteries this year and a Victron Multiplus II GX inverter/charger."

Very helpful, thank you. Did you already have PV panels and an inverter? Is there a risk of two inverters competing for power allocation?

I'm trying to figure out whether my SolarEdge inverter (HD Wave 5kw) would be capable of 'expansion' to talk to batteries, or if I'd need to replace this component entirely.

Help me pick a grid tied home battery, please

philedge — Thu, 18 Aug 2022 13:03:15 +0100

Your solaredge system would almost certainly support batteries- google Storedge. Your inverter may be able to manage the batteries with a direct DC connection or you may need a Storedge interface. With or without the Storedge interface youll need an energy meter on the house incoming mains wired to the inverter.

Beauty of the Solaredges battery storage is its DC coupled so is more efficient and you wont need to get DNO permission to connect the batteries as youll likely need to do with AC coupled PV and batteries.

Not cheap and I think there is a bit of a queue!!

Help me pick a grid tied home battery, please

jamesingram — Fri, 19 Aug 2022 17:36:03 +0100

still not convinced batteries on home solar make environmental or financial sense even though ive started fitting them for a few.
some people just want what they want.
getting hold of them currently is another thing altogether. 2-3 month lead on stock at least or pay through the nose

Help me pick a grid tied home battery, please

revor — Fri, 19 Aug 2022 19:15:18 +0100

Posted By: jamesingramstill not convinced batteries on home solar make environmental or financial sense even though ive started fitting them for a few.

I have a battery and it was questionable at the time of purchase whether it was justifiable or not but having had it now for over a year and with the price hike I am convinced it is. Last 4 months have used very little from the grid being on average 99% self sufficient. In Dec and January we were 27% self sufficient. With our export have been getting a good amount of credit which will more than cover us over winter and also just about cover our gas bill.

Help me pick a grid tied home battery, please

jamesingram — Sun, 21 Aug 2022 13:17:15 +0100

Posted By: revor
Posted By: jamesingramstill not convinced batteries on home solar make environmental or financial sense even though ive started fitting them for a few.

I have a battery and it was questionable at the time of purchase whether it was justifiable or not but having had it now for over a year and with the price hike I am convinced it is. Last 4 months have used very little from the grid being on average 99% self sufficient. In Dec and January we were 27% self sufficient. With our export have been getting a good amount of credit which will more than cover us over winter and also just about cover our gas bill.

I see some are batteries are claiming expected 80% output after 10 years. this is a lot better than 10 year life expectancy.
If you already have solar then moving usage as much as possible into day period actualy undermines battery return asumptions and benefits.
Low users it make less sense.
high users its a lazy expensive way to solve a problem , but that may suit some.

I think with smart night charging etc they start to look better but it really depends on costs and life span.
What do you think your saving a years currently at 27p kWh as a guide price
If we very roughly say money equates to polution then money saved is polution saved

Help me pick a grid tied home battery, please

jamesingram — Sun, 21 Aug 2022 13:18:48 +0100

heres an example of a battery install estimated benefits for a low user 2190 kWh pa
4.36kWp PV system
estimate daily usage 6000W
4.8kW battery sys
import 27p kWh
annual cost
start Â£591
with PV Â£315
With batteries Â£39
approx yearly saving with batteries over 10 years Â£270 pa

Help me pick a grid tied home battery, please

Doubting_Thomas — Thu, 25 Aug 2022 16:54:47 +0100

Posted By: jamesingramIf you already have solar then moving usage as much as possible into day period actualy undermines battery return asumptions and benefits.

James, thanks for the worked example. I'm interested in home batteries for the opposite reason - to make unavoidable non-daytime use from excess solar (e.g. early morning and evening dinner cooking which is dictated by school and working hours), since these are peak use times both domestically and .

Currently the storage I do have (SunAmp water heaters) is usually full by midday, everything I generate after this is therefore exporting to the grid during sunny mid-afternoon when national use is probably lowest. Surely it makes sense (carbon, maybe not financial) to store some of this to cover things once the sun has gone down?

Help me pick a grid tied home battery, please

revor — Thu, 25 Aug 2022 19:05:20 +0100

The thing to consider is that on your export payment you will get less than what you pay for drawing from the grid. This difference is what is saved by the battery and what helps to justify its purchase. The bigger the difference the more cost effective a battery is. After signing up to a variable export tariff based on the wholesale purchase price per kwh it made my battery less cost effective. e.g last month I was paying 27 p for my draw from the grid but was getting an average of 24p for my export. So if I did not have the battery I would have exported more and only needed to pay 3 p extra to draw it from the grid. So with that sum the 3p would not really justify the outlay for a battery. When I was only getting 5.5p for my export the battery was more justifiable. However the advantage with the battery is you can use it during a power outage but unless it is of a decent capacity then it will run out quickly. And then in winter when you get the outages there is not much sun around to keep it charged up during the day unless you have a turbine to top it up. You pays your money and make your choice.