diy solar

diy solar

Scored a heap of lead acids next port of call.

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Gros21

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Jun 23, 2021
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Well I know everyone here loves lithiums but I got 72 x 6v batterys which are either 120ah or 200ah effectively giving me 1000ah+ at 48v

I have 2 inverters already and 9.6kw of panels neither are battery compatible.

So I'm wondering what's the best way to hook this up.

Do I simply replace the 5kw inverter (6.6kw of panels) with a battery compatible inverter.

Or is there some other way I can monitor if I'm exporting and then charge the batterys and so forth.
 
Gros21 said:
Well I know everyone here loves lithiums but I got 72 x 6v batterys which are either 120ah or 200ah effectively giving me 1000ah+ at 48v
Click to expand...
Half of the 1000ah is usable, so 500ah. 9 bms to keep the 8s cells balanced?

If your current inverters are NOT battery capable, then there is no way to use them to get power in or out of the battery. You will need a battery capable inverter and solar charger (if not an aio).
 
DIYrich said:
Half of the 1000ah is usable, so 500ah. 9 bms to keep the 8s cells balanced?

If your current inverters are NOT battery capable, then there is no way to use them to get power in or out of the battery. You will need a battery capable inverter and solar charger (if not an aio).
Click to expand...
Lead acid doesn’t need BMS
 
There used. But only lightly.

They can from a power station.

They are used in an emergency so they still have control if they loose power for ages.

Was a temp battery bank while they put a new control building in.

I know my current set up isnt batt ready.

But not sure if it's worth getting a AIO to replace an inverter or what's the best way.

At this stage it's 100% free I've got cabling and a crimper.
 
What kind of inverter do you have that won't run off batteries?

AGM, Flooded or Sealed lead acid? If they're Flooded or (some) sealed, you can pop off the caps and top up the water in them and hit them all up with a hydrometer from the local auto parts store to get an idea of the condition of the batteries. AGM doesn't use liquid you can do that with so you can skip that step. Get them all charged up fully with a regular car charger in pairs (12v) and let them sit to see where they rest at. Group them up in sets that have the closest readings and go from there in AH sets (i.e. don't mix 100's and 250's in the same group) of 8 for your 48v.

Free batteries > Cheap batteries!!

Go ahead and build out your system with the batteries you have, when you're ready to convert to LFP in the future it's just a couple settings changes. Battery balancers would be handy but not necessary for the beginning. An AIO is the cheapest and simplest way to go and you'll need some bus bars to bring all the battery groups together to a single point. When connecting the battery groups, all the wires should be the same length between each bank and the bus bars. Here's the rub on that, the POSITIVE wires should be the same length, and the NEGATIVE cables should be the same length, but the POSITIVE and the NEGATIVE don't have to be the same length. I.E. if the longest length for Positive cables is 38in, then make all the Positive cables 38in, but if the longest Negative cable is 49in, then make the Negative cables all 49in. You however DON'T need your Positive cables to be 49in. Does that make sense?
 
The only downside to lead-acid batteries is that the float current can be significant, so standby power can eat your lunch.
 
wpns said:
All three of my extant inverters have no battery connection. Two EG418Kpv on the way, though...
Click to expand...
Sssooo... if inverting is the process of turning DC into AC, and your inverters have no battery connection, then what are they using for a DC source to invert into AC? Do they only work when the sun is out or something? :oops:
 
Rednecktek said:
Sssooo... if inverting is the process of turning DC into AC, and your inverters have no battery connection, then what are they using for a DC source to invert into AC? Do they only work when the sun is out or something? :oops:
Click to expand...
Umm, yes? Grid tied with no battery, that's how it's supposed to work...
 
"Port of Call" - Literally, you're on a boat?
Or asking what to do next?

A 1000 Ah 48V battery, 50 kWH, is good for 25 kWh @ 50% DoD, 35 kWh @ 70% DoD.
I've got one 20 kWh bank with Sunny Island inverters for grid backup, another at difference house is 25 kWh. Both AGM.

"I have 2 inverters already and 9.6kw of panels neither are battery compatible."
What inverter?

My system has SMA Sunny Boy grid-tie inverters, and they AC couple with Sunny Island battery inverters.
If yours have Rule-21 frequency-watts, they should AC couple with several brands of battery inverter.
 
Batterys are 1 year old I'm getting the apprentice to test the internal impedance of each battery and putting it on each cell.

I'm likely going then to wire them into 12v banks and using a decent charger on each bank.

Now I gotta find a AIO that does 240v and can put out some decent current or 2-3 smaller units.

I've got access to free copper busbar so that easy enough. But I've also got all the connections from the orginal set up. Plus flex from abot 35mm to 120mm2 with the battery crimpers to support it.

Tbh there is a good chance I can get more banks of identical specced batterys.

I might go 100% off grid with grid supply on a contactor for 6months. If I use next to no grid power I'll likely go a small Genny.
 
This system should work well with your batteries:

www.ebay.com

Battery Inverter Solar Cabinet: (QTY 2) SMA Sunny Island SI-6048 w/ Warranty | eBay

These cabinets were designed and built by DC Solar. If you use the cabinet as-is there are only 2 connections required to have a functioning system (battery connection and solar panel connection). This setup will generate power even when there is no connection to the power grid.
www.ebay.com

What model are your PV inverters? That will determine how well they play with Sunny Island.
 
How much wattage you looking to get? Most of the players out there have lots of 240v units and offer a couple 120v versions for them crazy 'Muricans.
 
Ok there are yuasa uxh125-6fr giving me 1125ah at 48v 2 pallets full. Each pellet 975kg or 1950kg total or 4300lb of pellets. Then prolly 400lb in cabling

As to wattage I'd say should be 10kw but that's going to be peak. I've ordered a 120a clamp for my Shelly system and can actually measure peak current.

I suspect being a single male In a 5 bedroom house it's like 2-3kw but potential is there for much more.

I'll see if I can grab 2 x 5 or 6kw units for some redundantcy
 
if these are standby batteries for a power plant, hospital or financial institution then they are not suitable for heavy cycling. they are designed to float for years and get cycled (hard) once or twice per year max when an emergency happens.

I had the same opportunity to get a bunch of these types of batteries several years ago and after investigating (contacting the japanese manufacture) they gave me the skinny on them.

Quite simply you are going to buy a bunch of gear, and then when you use the batteries they are going to die a quick (in regards to their capacity and normal float life) death. you will then need to buy a bunch more equipment + new batteries as the setup will share some gear but not all.

at least all of the lead batteries can be sold for scrap which will at least give you some cash to move on with.
 
Daddy Tanuki said:
if these are standby batteries for a power plant, hospital or financial institution then they are not suitable for heavy cycling. they are designed to float for years and get cycled (hard) once or twice per year max when an emergency happens.

I had the same opportunity to get a bunch of these types of batteries several years ago and after investigating (contacting the japanese manufacture) they gave me the skinny on them.

Quite simply you are going to buy a bunch of gear, and then when you use the batteries they are going to die a quick (in regards to their capacity and normal float life) death. you will then need to buy a bunch more equipment + new batteries as the setup will share some gear but not all.

at least all of the lead batteries can be sold for scrap which will at least give you some cash to move on with.
Click to expand...
I've been looking at the data sheets. They don't seem to bad they will likely be doing 25% dod.

While far from ideal I fully admit. I have the option to get more and could easy scale to 2 or 3000ah capacity.

If it dies a short painfully death I've lost nothing maybee $500 in misc items.

My inverters will be lithium ready. So then I'll likey go rack mount batts. I may go 2 x mpp solars or similar.

I'm not the first person to obtain these. But I'm the first person to obtain a full battery bank.
 
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