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Semi-portable solar generator build

DaGoose13

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Jul 28, 2021
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I'm thinking about building out a larger capacity semi-portable solar generator and have a few things I would like to ask.
I have looked at the new Bluetti AC300, but wanted to see what it would take to roll my own that might be more capable and possibly cheaper.

Looking at using the EG4 batteries and their rack that has rollers, so it will be semi-portable. Thinking of getting the 48v batteries and starting with 1 or 2 in the rack and expanding from there.

Questions:
1: Is there any benefit of going with a 24v battery over the 48v battery? I'm thinking not if I want to expand it to the maximum of 31KWh later.
2: Is there a good MPPT could handle the below.
A: Connecting to grid power and/or generator to charge the battery bank on an ad hoc basis?​
B: Handle a large array of solar panels or multiple arrays?​
C: Be able to connect to main house panel via a generator interlock or transfer switch?​
D: Be able to various devices via a dedicated power strip?​
Is there anything else that I'm not considering?

Thanks.
 
Welcome to the forums!

Will has a number of videos on different DIY solar generators and the Link at the top to DIY Solar Blueprints a lot of detail and his "current" best price list.

1: Is there any benefit of going with a 24v battery over the 48v battery? I'm thinking not if I want to expand it to the maximum of 31KWh later.
There's no real benefit to different voltages on small systems other than lower voltages are much safer. On larger systems, higher voltages can give you an edge in efficiency and higher voltages reduce current so reduce wiring costs.

2: Is there a good MPPT could handle the below....B: Handle a large array of solar panels or multiple arrays?
The MPPT selection needs to be based off the panel selection, see Figuring out how many panels in series and parallel based on your MPPT

A: Connecting to grid power and/or generator to charge the battery bank on an ad hoc basis?
An MPPT is independent of the grid, to connect to that you want to look into grid-tied inverters. There are some "all-in-one" inverters (e.g., the Sol-Ark) that include an MPPT.

C: Be able to connect to main house panel via a generator interlock or transfer switch?
All grid-tied inverters will have some plan for this.

Be able to various devices via a dedicated power strip?​
This is more commonly called a critical circuits panel. It's primarily how you decide to wire it (I don't use one, I decide what should be on/off when I need it from the breaker panel).

Hope that helps!
 
Welcome to the forums!

Will has a number of videos on different DIY solar generators and the Link at the top to DIY Solar Blueprints a lot of detail and his "current" best price list.
Thanks for the reply!

I have been watching them, but this is going to be a bit different than a normal solar generator. I didn't explain it well in my original post, so I'll give it another go.

Planning on using the EG4 batteries with their 6 spot rack (5.1 KWh up to 31.6 KWh), so it's semi-portable (I can roll it around if need be) and expandable (if I don't go with 6 batteries at the beginning).

Wanting to have it be able to be charged from solar and/or AC(grid/generator) at 120v or 240v (if possible).

Wanting to be able to power devices either with the dedicated power strip on the rack (120v and 240v if possible) and/or via a transfer switch to the main breaker panel on the house. Mainly wanting as much flexibility as possible

There's no real benefit to different voltages on small systems other than lower voltages are much safer. On larger systems, higher voltages can give you an edge in efficiency and higher voltages reduce current so reduce wiring costs.
Understood. I'll plan on the 48v system then.
The MPPT selection needs to be based off the panel selection, see Figuring out how many panels in series and parallel based on your MPPT
Panels may be ad hoc (will probably not have a fixed array), so wanting an inverter that has a large range of voltage and amps, so hopefully I can be more flexible with the panels.
An MPPT is independent of the grid, to connect to that you want to look into grid-tied inverters. There are some "all-in-one" inverters (e.g., the Sol-Ark) that include an MPPT.


All grid-tied inverters will have some plan for this.
Thanks. Been reading up on these and I think I may need to find a hybrid inverter for what I'm wanting to do, so that way I can use it without it being connected to the grid.

Are there any good lists of hybrid inverters or is there a good way to get a grid-tied inverter to work the way that I'm planning on?
This is more commonly called a critical circuits panel. It's primarily how you decide to wire it (I don't use one, I decide what should be on/off when I need it from the breaker panel).
This is an actual power strip on the rack. I want to be able to power items outside of the home if need be (electric chain saw, etc).
Hope that helps!
It did!
 
Panels may be ad hoc (will probably not have a fixed array)...
Well, that's different! Putting panels into serial/parallel to get the proper voltages is a pain (for more see What does it mean to have solar panels in parallel and series?).

If the panels are from different suppliers with different voltages/currents and/or varying amounts of shade and/or frequent reconfigurations you might want to explore microinverters. It's good for solar->to->grid, but requires AC Coupling to hook with a battery or a system smart enough to control them (e.g., Powerwall, Ensemble) for off-grid power.
 
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