Back2Basics: My Genset is 240V,. Does that matter for my Inverter selection?

Old_Skewler

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It does NOT mean that you can't charge your batteries AND use AC in the cabin. It means that the AC will be coming from your generator and not the inverter. This means that the draw from charging and the loads running cannot exceed the capacity of the generator.
Clarified! I totally misread you the first time around. It makes sense.

Now practical question, with an 14kW generator and possibly a 4kW inverter on the horizon, do I risk getting into the red zone you just mentioned? My intuition tells me I should not be concerned but aware of this physical limitation.
 

Hedges

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I went to the basement and double-checked: you are correct, (4) wires come from the genset, (3) insulated (black, red, white) and an uninsulated copper wire. Picture attached as requested.

I didnt realize the uninsulated wire was actually a piece of the puzzle.

I see a green screw to tie box to neutral busbar, and both white and bare wires going to the neutral busbar.
That means this box is the location where neutral and ground are bonded together. In that case, neutral and ground should be isolated at the generator.
Also in this case, there should be a wire from this neutral busbar to a ground rod. I don't see that. (It could be at the generator.)

And if you thing SJ got your head spinning, wait until he gets into grounding!

Too late!
I just spun it 'round again!
 

smoothJoey

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@Old_Skewler when boondox says inverter it is more aptly described as and inverter/charger.
Even more aptly described as an inverter/charger/transfer switch.
 

Old_Skewler

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Consider diagram at end of this data sheet. Ignore utility grid and transfer switch, which you don't have.


Sunny Island will connect to generator, pass through AC to loads and charge battery (up to 56A AC input.)
(There are a few stupid inverter designs that can't charge batteries during pass through. But SMA and many others function well.)

Sunny Island has a relay it uses to auto-start the generator based on battery depth of discharge. At night, it will wait longer to avoid noise.
A dual Sunny Island plus Sunny Boy system would work well, but is not cheap. MSRP about $15k for two, 6kW Sunny Island and two, 6kW Sunny Boy. You can probably get it for half that price.
Some other brands have hybrids which perform all the desired functions for less money. They may not be as durable or able to start heavy motor loads.
Bro, that is WAY out of my price range. I am trying to bargain a old stock Alpha Solaris inverter for $700 and you show me a $15K solution? Inverters only, with no batteries? To power my 2.5 kW Peak load?

I am already considering "moving up" to a brand new Magnum for around $1,700. But that is about my budget for an inverter. This SMA solution with multiple inverters is way beyond my pay grade.
 

smoothJoey

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I don't see any double pole breakers which says none of your loads is 240VAC.
Also do I see a heat mark on the main neutral and on the main ground?
 

Hedges

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  • Wow
Reactions:Old_Skewler

Why so shocked? The price?

I got me a pallet of Sunny Islands, and a pallet of Sunny Boys, so unit price was lower but I had to buy a full pallet. Added up to more dollars that I realized, by the time I got done with all the rigid conduit and copper wire I used.

Some of the people before me in the surplus/closeout foodchain paid about $500 for Sunny Island, but I wasn't there so I paid markup. Price on the eBay market has been rising from $1250 to about $2500 or $3000 now.

You might pick up a pair of Sunny Island in an enclosure for $5000, and an old model Sunny Boy for $1000.
There are other brands like GroWatt that have hybrids for $800 to $2000.

But how much are batteries going to cost you? It's all a system cost balancing act.
 

Old_Skewler

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I don't see any double pole breakers which says none of your loads is 240VAC.
You are correct. Nothing is 240V in the cabin. Am I missing out on the goodies? Rhetorical question, I already have too much on my plate to even consider re-wiring anything to 240V.

But i'd be interested in knowing if makes sense to have a 240V outlet for carpentry tools in the future.

Also do I see a heat mark on the main neutral and on the main ground?
Whew... there you go again, throwing digestible knowledge sprinkled with head spinning comments. I have no idea what you are talking about now or whether I should try to understand it.

:)
 

smoothJoey

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I have poor eyesight but the main white wire appears to have heat damage to the insulation.
Please inspect the wire and see if its just discoloured or if it appears to have melted a bit.

Also you have 12 breakers.
10 of them are on one phase while 2 are on the other.
That is interesting to say the least.
Your loads may not be balanced which is probably going to be hard on the generator.
 

Hedges

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Also do I see a heat mark on the main neutral and on the main ground?

Dirty spots too. If heat, hope that was an accident before connected, and not something that occurred in the present setup.
 

smoothJoey

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Dirty spots too. If heat, hope that was an accident before connected, and not something that occurred in the present setup.
Not sure if its related but on the face of it 10/12ths of the current in his setup is going back on the neutral.
 

Old_Skewler

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Why so shocked? The price?
The price and the fact that it would take MULTIPLE expensive devices to achieve what it seems like it takes other manufacturers one device.

SMA is just not the solution for a broken ass dude like myself trying to put together a small system to keep a fridge and some laptops running.

But i'll give you this: it looks fucking amazing and professional.

But how much are batteries going to cost you? It's all a system cost balancing act.
I am hoping to spend about $1,600 for (4) batteries. Whatever capacity I get at the time of purchase. Hopefully 100 Ah. Unlikely lithium technology.
 

Old_Skewler

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I have poor eyesight but the main white wire appears to have heat damage to the insulation.
Please inspect the wire and see if its just discoloured or if it appears to have melted a bit.
Please, don't scare me. Other photo attached.


Also you have 12 breakers.
10 of them are on one phase while 2 are on the other.
That is interesting to say the least.
Your loads may not be balanced which is probably going to be hard on the generator.
I have to track down all circuits and label them.

I do not know why/how the cabin was wired. But I understand what you mean.

I also suspect once I have all breakers labeled correctly, this should be something easy to correct.
 

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smoothJoey

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Could you please explain your line of thought? I thought what you said earlier made sense.
I can't visualize how the phases are interleaved in a panel but I'm pretty sure they are interleaved.
My brain and eyes don't work like most folks.
I'm sure that will come as no surprise to many here.

Hopefully somebody else will weigh-in.
 

Hedges

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The price and the fact that it would take MULTIPLE expensive devices to achieve what it seems like it takes other manufacturers one device.

SMA is just not the solution for a broken ass dude like myself trying to put together a small system to keep a fridge and some laptops running.

But i'll give you this: it looks fucking amazing and professional.


I am hoping to spend about $1,600 for (4) batteries. Whatever capacity I get at the time of purchase. Hopefully 100 Ah. Unlikely lithium technology.

You have a 12kW 120/240V generator, and people were explaining that if you connected a 120V inverter/charger it could only make use of half the generator wattage. So I described a system that could use all of it.

If you have 2500W of load, maybe a 3kW 120V inverter and a 3kW generator would fit well. (Although, if you have a motor to start, need enough surge from the inverter. Induction motors like many pumps are especially difficult.)

It the battery will be 48V 100 Ah, about 5kW, the charge current it accepts will be limited. 2500W if lithium. 1000W for some AGM. 700W maybe for FLA.

I started out with four, 12V 100 Ah AGM on one Sunny Island. That was about $1200. If you buy FLA you could get 200 Ah for the price.

After I got a pallet of Sunny Island and installed four, I put in eight, 6V 400 Ah AGM. That cost $5000, which I didn't want to spend, but is about the minimum for my inverters. FLA would cost less but more maintenance. Yeah, I had more cash to blow. Silicon Valley engineer, everything here costs more so the higher end PV stuff isn't as big a part of our budget. Property taxes are the worst (mortgage is more, but at least I know what I'm getting for it.) I had grid-tie PV with Sunny Boy for 17 years before I finally splurged and put in battery backup, just because I could. It was nice during shelter-in-place and work from home. It works well (except Sunny Boy doesn't like the VFD I have on a 3-phase pool pump.)
 
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