diy solar

diy solar

About to spend a lot of money tomorrow on this system (am I making a mistake?)

sunshine_eggo said:
No. You'll need to run 4 wires now. L1, L2, N and G. It probably comes down to the following:

Is it cheaper to run 4 wires to each cabin, or is it cheaper to run 2 wires to each cabin and have an autotransformer at each cabin? I would ask your dealer about that.
Click to expand...
If you are doing split phase over the long runs what purpose do the auto transformers serve?
 
Well, the good news *I think* is that the Multi-Plus II 48/8000 model has a peak power of 15,000W so I'm assuming that will take care of the surge.

If not I'm going to switch to coal.
 
AlaskanNoob said:
Doesn't appear so....
Click to expand...

I just like to be a contrarian. So I kept digging. :)
My professors hated me. A 'prime' government contractor, too. I basically told them their baby was ugly.
(but I guess they got the last laugh, when we paid them $millions to do it over.)
 
One question I still have on the Victron stuff. The two SmartSolar charge controllers 450/200 can deliver 400 amps for charging. But the Multiplus 2 48/8000 says its max battery charging is 110 amps.

What is charging the batteries and if it is the Multiplus is it going to be limited to 110 amps?

I ask as my Friday night is getting less fun...
 
Hedges said:
I just like to be a contrarian. So I kept digging. :)
My professors hated me. A 'prime' government contractor, too. I basically told them their baby was ugly.
(but I guess they got the last laugh, when we paid them $millions to do it over.)
Click to expand...

You're the kind of guy many don't like. But need. And they don't like that they need you.

But I like you AND need you!
 
AlaskanNoob said:
Perfect. So the expensive wire just tripled because whatever could flow through one wire before has been split up and needs to go through three big wires now? I knew I didn't like science. The hits just keep on coming!

B and C are very far from each other with A between them. 800 feet or so.
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Depending on the price of copper, consider step-up to 480V (maybe 960V with center tap grounded?) using isolation transformers.
(Maybe autotransformers can be used too; think either requires wiring a ground. Autotransformer to double voltage would be half as much core and half as much copper as isolation transformer.)
 
AlaskanNoob said:
One question I still have on the Victron stuff. The two SmartSolar charge controllers 450/200 can deliver 400 amps for charging. But the Multiplus 2 48/8000 says its max battery charging is 110 amps.

What is charging the batteries and if it is the Multiplus is it going to be limited to 110 amps?

I ask as my Friday night is getting less fun...
Click to expand...

I think Multiplus takes in power from its AC input (e.g. generator) and dumps 110A into battery.
You're free to connect SmartSolar, a DC generator, or any other source to battery as well.

Probably Multiplus wants to know how many amps. Or, with lithium and BMS, maybe it just asks.
Part of the Victron ecosystem is a battery shunt, which would measure net current into the battery considering various charging sources, inverters, DC loads. That would be needed if lead-acid, maybe not necessary for lithium with communication to BMS.
 
Hedges said:
I think Multiplus takes in power from its AC input (e.g. generator) and dumps 110A into battery.
You're free to connect SmartSolar, a DC generator, or any other source to battery as well.

Probably Multiplus wants to know how many amps. Or, with lithium and BMS, maybe it just asks.
Part of the Victron ecosystem is a battery shunt, which would measure net current into the battery considering various charging sources, inverters, DC loads. That would be needed if lead-acid, maybe not necessary for lithium with communication to BMS.
Click to expand...
Do does that mean the 450/200 SmartSolar charge controllers will provide 200 amps (each) to charge the battery and the MultiPlus might provide an additional 110amps?

Please say yes....
 
So my Victron dealer must have this crazy idea that his Friday night is better spent doing something other than answering my questions. But we did put in our order for 8 x US5000s that we're looking forward to getting in ten weeks or so.

Now I just need to make sure I can charge those batteries with the Victron SmartSolar MPPTs and won't be bottlenecked by the MultiPlus II to only 110 amp of charging.

Then I can move on to trying to figure out what kind of wires I need to trench to the cabin.
 
Last edited:
AlaskanNoob said:
Do does that mean the 450/200 SmartSolar charge controllers will provide 200 amps (each) to charge the battery and the MultiPlus might provide an additional 110amps?

Please say yes....
Click to expand...

Yes.

Each SCC can provide 200A. If MultiPlus has AC feeding it and it's charger function is rated 110A, that goes in too. There is going to be some AC amperage limit on the input, so if all 6kW or so is going to battery charging that may limit how much can feed through. You said Honda 7000, so I guess there's only 1kW left anyway.

Figure out what you're doing to keep batteries warm. The charge the can accept will be reduced when cold. BMS probably implements a low-temperature charge disconnect. I don't know which if any of your equipment would reduce charge current if BMS asks them to. I also don't know if BMS is aware of reduced current limits at low temperatures.

Possibly the only controls you will have is max current setting of SCC and disconnect temperature of BMS. In which case I would suggest selecting a max current, a temperature cutoff where that current is acceptable, and try to keep batteries heated above that temperature.
 
smoothJoey said:
If you are doing split phase over the long runs what purpose do the auto transformers serve?
Click to expand...

The autotransformer provides the split phase. The question is do you do it at location A and send split phase to B & C, or do you send single phase from A to autotransformers to B & C.

AlaskanNoob said:
Well, the good news *I think* is that the Multi-Plus II 48/8000 model has a peak power of 15,000W so I'm assuming that will take care of the surge.

If not I'm going to switch to coal.
Click to expand...

Yes, but there will not be a significant surge from the heat pump (if any). Well/water pumps and other non-"inverter" electric motors typically do; 4-10X their run current.

AlaskanNoob said:
One question I still have on the Victron stuff. The two SmartSolar charge controllers 450/200 can deliver 400 amps for charging. But the Multiplus 2 48/8000 says its max battery charging is 110 amps.

What is charging the batteries and if it is the Multiplus is it going to be limited to 110 amps?

I ask as my Friday night is getting less fun...
Click to expand...

110A of AC input from the generator. 110A is going to be 5000W+

Learn this: https://www.victronenergy.com/live/multiplus_faq

Hedges said:
I think Multiplus takes in power from its AC input (e.g. generator) and dumps 110A into battery.
You're free to connect SmartSolar, a DC generator, or any other source to battery as well.

Probably Multiplus wants to know how many amps. Or, with lithium and BMS, maybe it just asks.
Part of the Victron ecosystem is a battery shunt, which would measure net current into the battery considering various charging sources, inverters, DC loads. That would be needed if lead-acid, maybe not necessary for lithium with communication to BMS.
Click to expand...

Yes, BMV-702 (don't need bluetooth) with temp sensor (extra) and the Cerbo GX will tie everything together nicely.
 
Hedges said:
Yes.

Each SCC can provide 200A. If MultiPlus has AC feeding it and it's charger function is rated 110A, that goes in too. There is going to be some AC amperage limit on the input, so if all 6kW or so is going to battery charging that may limit how much can feed through. You said Honda 7000, so I guess there's only 1kW left anyway.

Figure out what you're doing to keep batteries warm. The charge the can accept will be reduced when cold. BMS probably implements a low-temperature charge disconnect. I don't know which if any of your equipment would reduce charge current if BMS asks them to. I also don't know if BMS is aware of reduced current limits at low temperatures.

Possibly the only controls you will have is max current setting of SCC and disconnect temperature of BMS. In which case I would suggest selecting a max current, a temperature cutoff where that current is acceptable, and try to keep batteries heated above that temperature.
Click to expand...
Thank you. That makes sense.

Batteries will be ten feet underground with an insulated roof over top and an insulated shed on top of that. So like a root cellar, should stay above freezing especially with the equipment heating it up.
 
Don't take this the wong way, but is this seriously a DIY job? I would highly recommend getting a solar Installer for something of this size and scale.
 
robby said:
Don't take this the wong way, but is this seriously a DIY job? I would highly recommend getting a solar Installer for something of this size and scale.
Click to expand...
So far we do not see the wiring diagram yet, I think OP should provide it so we can inspect and give suggestions and see if there is something amiss or not.
 
robby said:
Don't take this the wong way, but is this seriously a DIY job? I would highly recommend getting a solar Installer for something of this size and scale.
Click to expand...
I doubt it. Not for me anyway.

My intent is to learn as much as I can about how to do it, and then come up with a game plan for what needs to be done and with what components and material. Once I think I know how to get it done, I'll likely hire an electrician to go over the plan and to give me guidance.

Then I'll do the trenching and lay all the wires (but not cover them up), set up the battery room underground with all the components on the wall and the battery racks in place, build a ground mount and install the panels. Once everything is in place I'll have the electrician come up and bless it, plug everything in, and go from there. Then back fill the trench.

That's the plan anyway.
 
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