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Silly question about 3kw solar, charger and battery
#1
Hello people,

Im quite new in the solar panel world and I have a stupid question about it.

2 weeks ago a company placed 10 solar panels on our roof (10x300w panels)
With a Growatt converter that supplies our house electricity and overproduction goes back to the net.

Now id like to install batteries to store the overproduced electricity.

Right now I have collected 24 new Geld batteries (12v 12ah batteries)

The solar panels are connected in 2 pairs 2x5 panels in serie.

My question, how and wich battery charger do I need to install batteries in this system, I prefer Victron.

Thank you for your help and advice.
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#2
You basically need to ditch your current inverter for a hybrid setup. The One you got now are for grid tie only. With that Said you can potentially get around it with some built electronica but that isnt easy. Just installing a battery Charger wont work. You need to take that energy from somewhere and and get it back when needed Wink
Gizmosis350k likes this post
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#3
(04-28-2019, 02:42 PM)daromer Wrote: You basically need to ditch your current inverter for a hybrid setup. The One you got now are for grid tie only. With that Said you can potentially get around it with some built electronica but that isnt easy. Just installing a battery Charger wont work. You need to take that energy from somewhere and and get it back when needed Wink

I see, seems more work then i tought.

So its not possible to place some batteries between the panels and converter?
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#4
(04-28-2019, 12:55 PM)Hasekura Wrote: My question, how and wich battery charger do I need to install batteries in this system, I prefer Victron.

You don't need to do anything to your existing system.

Buy a Victron MultiPlus II (3000 or 5000va) and a CG smart meter - the MPII is a combined inverter/charger, the smart meter will tell the charger when there's a surplus and divert it to battery. This sits parallel to the grid, keeping your grid consumption at a negligible amount (while you have battery capacity available) - add a MPPT if you want DC coupled PV.

https://www.victronenergy.com/live/ess:d...ion-manual

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#5
(04-28-2019, 04:03 PM)Sean Wrote:
(04-28-2019, 12:55 PM)Hasekura Wrote: My question, how and wich battery charger do I need to install batteries in this system, I prefer Victron.

You don't need to do anything to your existing system.

Buy a Victron MultiPlus II (3000 or 5000va) and a CG smart meter - the MPII is a combined inverter/charger, the smart meter will tell the charger when there's a surplus and divert it to battery. This sits parallel to the grid, keeping your grid consumption at a negligible amount (while you have battery capacity available) - add a MPPT if you want DC coupled PV.

https://www.victronenergy.com/live/ess:d...ion-manual


That looks easy and something that i am looking for.

So if I understand this correctly the setup can be like:


Current situation:
Solar Panels --> Growatt converter --> Meter Box. (on the same group)

New situation:
Solar Panels --> Growatt converter --> Multiplus II --> Meter Box. (on the same group)
                                                             |
                                                         Batteries
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#6
I don't know what you mean when you say "on the same group" 

The Victron ESS sits parallel to the grid, so (depending on the regulations wherever you live) will likely be connected via a dedicated radial connection and it's own breaker - in much the same manner as your recent PV installation should have been done.
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#7
Ahh victron have it. Nice.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#8
Also, if you are going to start towards batteries, small lead acid ones will fail early & not give you much usable capacity.
Those batteries you have collected are only 12Ahr each, so say 48V system = 4s6p = 72Ahr.
You can only use about 30% of this or LA batteries fail much faster so that's only about 22Ahs usable.
Your solar would charge them too hard (too much current) and most household loads would drain them very quickly (& at higher current than is good for them).
You'd be much better starting with Lithium from day 1.
Running off solar, DIY & electronics fan :-)
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#9
(04-29-2019, 12:15 AM)Redpacket Wrote: Your solar would charge them too hard (too much current) and most household loads would drain them very quickly (& at higher current than is good for them).
You'd be much better starting with Lithium from day 1.

You are correct with regard to the battery type and capacity - but the charging current can be configured down to suit even very small banks - Li is the much preferred battery chemistry.
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#10
(04-28-2019, 02:42 PM)daromer Wrote: You basically need to ditch your current inverter for a hybrid setup. The One you got now are for grid tie only. With that Said you can potentially get around it with some built electronica but that isnt easy. Just installing a battery Charger wont work. You need to take that energy from somewhere and and get it back when needed Wink

Is it really that complex ?
I have the opportunity to do the same setup (solar panels pumping into the network) and I was thinking that after the system is done I'd may be able to 'cheat' and charge 18650 packs too at day and use them at night. Is this viable ?


@Hasekura most interesting. I'll study that soon. Looks simple and doable.
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