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Grid Tie inverter / charger with AGM batteries

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Stadica
Noobie
Posts: 2
Joined: Tue, 07 Apr 2020, 10:26

Grid Tie inverter / charger with AGM batteries

Post by Stadica »

Hi, I’m after some advice on jumping in feet first into some battery storage. I have been able to obtain 48 2v 220ah AGM Yuasa cells for the right price, I have them in two 24 battery banks giving me 48v 440ah of capacity. I’m looking for a economical inverter charger to use in a grid tied situation. I have seen the victron multiples II and the goodwe gw5000s-bp. I currently have a goodwe 5kw solar inverter with 6.6kw of panels, and am weighing towards the goodwe gw5000sbp. Has anyone had success with this inverter charger using AGM batteries? Are they very configurable to suit the AGM battery? I ask these questions as I found a manual online that states lead acid as options but another part in the manual contradicts itself and says only compatible with lithium batteries on their approved list. Any help would be greatly appreciated.

Thanks

Newbie to Battery systems. 8-)

antiscab
Senior Member
Posts: 2601
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

Re: Grid Tie inverter / charger with AGM batteries

Post by antiscab »

Where are you based?

you would likely get more bang for your buck taking some loads off grid using a large 96v UPS and adding more (offgrid) solar to support using second hand gumtree hardware, assuming you have space for more solar. That solution is several $100.

Do you have an export limit? What is it?

putting a 48v battery on grid is a $2k excercise, and you will get roughly 70% round trip efficiency (95% each way to 48v, battery itself is optimistically 80%, 96% from hvdc to grid).
so basically 14.5kwh in to get the max usable 10kwh out. Though if you're in WA, it would allow you to get around the 5kw inverter size limit (especially by using a GW2500-bp) allowing you install more solar.

at the moment, the two ways on grid batteries work out (even where the battery itself is free) is where it facilitates the installation of a (much) larger solar array, or where you participate in a VPP and get paid above the odds for what you export.
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

antiscab
Senior Member
Posts: 2601
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

Re: Grid Tie inverter / charger with AGM batteries

Post by antiscab »

I just realised I didn't actually answer your question - the 48v inverters have traditionally worked with lead acid natively, getting them to work with lithium has been the real trick.

The default is usually a 3-stage lead acid charge profile (voltage and current limits configurable)
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

T1 Terry
Senior Member
Posts: 1109
Joined: Thu, 30 Sep 2010, 20:11
Real Name: Terry Covill
Location: Mannum SA

Re: Grid Tie inverter / charger with AGM batteries

Post by T1 Terry »

Do you have grid tie solar at the moment? If you don't, you need to get the tick of approval for your battery system and inverter before they will let you put it on the grid, then you need to jump through the hoops to get the while lot certified. Forget about using anything second hand for a grid tie set up, they won't approve it.
I would also recommend using the battery pack and some second hand solar to make an off grid system that you can run part of your house loads on so you can reduce the amount you have to buy from the grid. They can't say boo about the amount of solar or inverters you use for an off grid system as long as you don't try to feed it back into the grid.

T1 Terry
Green but want to learn

Stadica
Noobie
Posts: 2
Joined: Tue, 07 Apr 2020, 10:26

Re: Grid Tie inverter / charger with AGM batteries

Post by Stadica »

Thanks for your replies.. Yes I currently have a 5kw grid tied solar setup, Im located in NSW. I think my understanding of how these battery charger inverters work maybe wrong, but I thought that these units would not allow power from your batteries to be exported back to the grid and that it would be only used to supplement solar panels and / or use the stored energy during peak times to use less from the grid. This is a link to the goodwe I was looking at https://www.goodwe.com/Public/Uploads/s ... MANUAL.pdf. Maybe i may need to rethink my use and setup of this battery bank now.....

antiscab
Senior Member
Posts: 2601
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

Re: Grid Tie inverter / charger with AGM batteries

Post by antiscab »

Stadica wrote:
Tue, 07 Apr 2020, 16:01
I currently have a 5kw grid tied solar setup, Im located in NSW. I think my understanding of how these battery charger inverters work maybe wrong, but I thought that these units would not allow power from your batteries to be exported back to the grid
if you change your inverter, the grid operator will likely want to know about it.
Basically approvals need to be sought for everything up until the inverter

If you put say a goodwe GW2500-BP between the solar panels and your present inverter, you would not need to get any new approvals, as the inverter remains the same.
You would also be able to install more panels and still claim STCs (using a CEC accredited installer)

To claim STCs, the solar panels need to be brand new, but the batteries don't.
The goodwe GW2500-BP would need to be too, not that there are any available second hand anyway
but again $2000 excercise just getting the the battery hooked up to the inverter. But it may facilitate being able to install another 3.25kw worth of solar (2.5kw x 1.33 max) for likely only another $2000.

I'm actually grappling with a similar situation myself, though the batteries I have on hand are nimh, and more like 70% round trip efficiency.

another point to consider - an on grid battery will generally increase CO2 emissions, due to it's losses in storage, unless, it's use facilitates more renewable energy capacity.
being able to install more solar is an obvious one.
being part of a VPP is another, as it allows the grid to charge the battery, instead of curtailing large scale solar and wind farms when demand drops too far for the old coal stations to cope.
https://repositpower.com/ is the only one in NSW that I'm aware of - though wouldn't be as useful with the GW2500-BP (as it can't charge from the grid, though it can certainly feed in at times of peak demand, when the solar hasn't already maxed out the grid tie inverter)
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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