Silly question about 3kw solar, charger and battery

H

Hasekura

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Apr 28, 2019
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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.
 
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 ;)
 
daromer said:
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 ;)
Click to expand...

I see, seems more work then i tought.

So its not possible to place some batteries between the panels and converter?
 
Hasekura said:
My question, how and wich battery charger do I need to install batteries in this system, I prefer Victron.
Click to expand...

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'sa 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:design-installation-manual


image_mtujrp.jpg
 
Sean said:
Hasekura said:
My question, how and wich battery charger do I need to install batteries in this system, I prefer Victron.
Click to expand...

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'sa 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:design-installation-manual


image_mtujrp.jpg
Click to expand...

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
 
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 muchthe same manner as your recent PV installation should have been done.
 
Ahh victron have it. Nice.
 
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.
 
Redpacket said:
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.
Click to expand...

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 preferredbattery chemistry.
 
daromer said:
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 ;)
Click to expand...

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.
 
The simplest way would be to have a regular mains powered battery charger switched when your solar input is high.

A typical grid tied solar panel installation usually runs high voltage DC (200-400V ish) & you don't want to mess with that.
 
If you already have a grid tied setup, like the OP, you want to build an AC coupled system with a hybrid inverter like the Victron mentioned previously. If you look up those systems, they go between your current inverter and the panel/grid and either let it feed your house, charge batteries, or sell to the grid.
 
hazSolar said:
..... they go between your current inverter and the panel/grid and either let it feed your house, charge batteries, or sell to the grid.
Click to expand...

Victron inverter/chargers are installed parallel to the existing grid tied installation not "between".
 
Very stupid maybe.
Disconnect your array and connect it directly to a vectron unit?
 
100kwh-hunter said:
Very stupid maybe.
Disconnect your array and connect it directly to a vectron unit?
Click to expand...
The problem with this from my experience isCity Inspection. By going off-grid I was able to legally bypass all thePower Company (not so good)requirements. IF you hook victron directly (rather than parallel) I would imagine you would need to revisit Power Company requirements/permits. Maybe by doing parallel - you could avoid that.
P.S. I liked the question :)
 
Same problem over here, and worse.
Despite power company requirements/permits
You are not allowed to go offgrid, they want to control.
You must deliver to them, battery's in large numbers is not allowed anymore(agm, lead acid ect) 2 max.
Try to get a tesla home battery.....ect ect
You must use something.

So built it of slowly...so i will only have a electric cooking plate/furnas on the grid :)
 
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