1200 Watts of solar and 600 AH of Battle Born

[Ctopher61]

Was thinking the same thing. Number 2 wire sounds like it might create more resistance than anything else. Just my thoughts, without taking pencil to paper and doing a calc.

[E12Cheng]

A couple of folks asked why I was using two #2 cables for my run from the roof to the basement. The run will end up being 25 feet.
A #2 AWG cable has a 33.6mm cross sectional area. Two #2 AWG cables would equal 67.2 MM cross sectional area. A 2/0 AWG cable has 67.4mm cross sectional area close to the two #2 AWG cables I’m installing.
Using a minimum conductor size calculator, Copper at 20 feet in a DC circuit at 12 volts with 90 amps requires a 2/0 copper conductor. With the 1200 watts of solar on the roof I don’t think I will capture the entire 100 amps so two # 2 AWG cables should be adequate for this install. Please if my math or assumptions are off let me know. The PDF is a drawing of the system I'm installing

[N1282X]

Your solar panels are not 12 or 14 volts output. At best your 1200 watts of solar are going to put out 800 watts of real power. divide that by 40 volts you will have about 20 amps maximum going down those cables....

[PNW Fireguy]

Your concept is not correct. However the result works out for you to address voltage drop. There are some great tutorial videos regarding solar system wiring, wire protection on the alt e website.

[Mclord]

Originally Posted by N1282X

Your solar panels are not 12 or 14 volts output. At best your 1200 watts of solar are going to put out 800 watts of real power. divide that by 40 volts you will have about 20 amps maximum going down those cables....

X2
Need to know the voltage output of the array to determine amps. Watts = Amps x volts. Victron has an xl spread sheet that allows you to put in your criteria. I think you will find that #2 is huge overkill.
I have another question. How are you dealing with the second hot leg of the incoming shore power? The multilpus is only capable of handling one leg of 120 volt. Perhaps I’m missing something.

[E12Cheng]

L1 will be inverted and L2 will not. Will only have power to L1 off of the batteries

[Mclord]

Originally Posted by E12Cheng

L1 will be inverted and L2 will not. Will only have power to L1 off of the batteries

I’m still confused. I think what your saying is that Multiplus AC 1 out will be inverted off the batteries when not on shore power. The Multiplus AC 2 will have pass through power but only when connected to shore power. This is my current set up on a 30 amp system. I installed a split AC panel and put the heavy load items (water heater, air conditioner) on the Multiplus AC 2 out leg.
We’re planning on ordering a 3120RL and designing our solar/lithium system.
Your PDF doesn’t show where the shore power L2 is going. It appears that you are splitting you AC between the two panels with L1 and L2 off the Multiplus which is only capable of 30 amps total. I’m considering one of two alternatives. First option is this.
AMSolar makes a smart phase selector allowing for the both incoming shore power legs, sending one phase to the Multiplus and receiving the one L1 out off the Multiplus and then splitting it back to two phases to go to the 50 amp AC distribution panel. This will allow the inverter to add amperage from the batteries to both sides of the panel. This is a user beware situation as running things like electric heat or air conditioning will put a significant draw on the batteries when not on shore power and will require some discipline.
My second option is to use shore power L1 to the Multiplus and only use the Multiplus L1 out to one side of the AC distribution panel. Then run the shore power L2 to the other side of the AC distribution panel.
I’m likely going for option 1.

[Mclord]

This is a link to the AMSolar Smart Phase Selector:

https://static1.squarespace.com/stat...or+Diagram.pdf

Also to note, I will be removing the inverter installed by Keystone.

Just a comment on battery options. I currently have a 300ah ReLion 8D battery and will go that route again. It has a built in BMS which has worked flawlessly and being an 8D negates the need for for battery interconnects. This along with the built in BMS simplifies the install. I have measured the battery compartment on the 3120RL to confirm it fits.

[Sparky55]

Originally Posted by Mclord

I’m still confused. I think what your saying is that Multiplus AC 1 out will be inverted off the batteries when not on shore power. The Multiplus AC 2 will have pass through power but only when connected to shore power. This is my current set up on a 30 amp system. I installed a split AC panel and put the heavy load items (water heater, air conditioner) on the Multiplus AC 2 out leg.
We’re planning on ordering a 3120RL and designing our solar/lithium system.
Your PDF doesn’t show where the shore power L2 is going. It appears that you are splitting you AC between the two panels with L1 and L2 off the Multiplus which is only capable of 30 amps total. I’m considering one of two alternatives. First option is this.
AMSolar makes a smart phase selector allowing for the both incoming shore power legs, sending one phase to the Multiplus and receiving the one L1 out off the Multiplus and then splitting it back to two phases to go to the 50 amp AC distribution panel. This will allow the inverter to add amperage from the batteries to both sides of the panel. This is a user beware situation as running things like electric heat or air conditioning will put a significant draw on the batteries when not on shore power and will require some discipline.
My second option is to use shore power L1 to the Multiplus and only use the Multiplus L1 out to one side of the AC distribution panel. Then run the shore power L2 to the other side of the AC distribution panel.
I’m likely going for option 1.

I’ve considered both. I’m using option 1 currently. Yes be aware of usuage on the batteries

[E12Cheng]

My other concern is the 12 Vdc converter/charger in the PD 4575. The Victron 3000 inverter/ charger will be charging the batteries and the charger in the electrical panel may not play nice with the victron. I’m thinking of removing the converter and power the 12 loads off the dc distribution panel.

[Sparky55]

Yes. I simply disconnected the red and black 12v converter wires and tape them off. You can also disconnect the 120v circuit to the converter/ charger and tape them off as well. I left the charger in place in case something ever goes wrong with the victron invert/charger unit. I could reconnect the previous charger in emergency.

[scottz]

Originally Posted by jetskier

10awg would work from the panels to the controller if you run half the panels in series and tie them in parallel at the combiner. If you're doing a full parallel system, you will need the larger size. 2 or 4 awg from the controller to the batteries is optimal for the 100a controller output at 13-14 volts

My 855w array operates at around 50-55v at 17 amps in peak conditions feeding the controller. Well within the permitted current limit of 10awg wire (30amps).

Originally Posted by PNW Fireguy

While true why would one not take advantage of the larger wire size for lower voltage drop?

It's all math. My 400W 24V system will have a maximum of 17A to the controller; nominal will be much less, 10A or less. #10 wire is ok for that. Being conservative, double the current from the controller to the batteries, so running #6 wire (the biggest my 100/50 terminals will accept) should be good (probably be ok with #10 on that run also).

Is my math sound?

There is not much downside to using heavier wire; weight & expense, but the biggest (for me anyway) would be the difficulty wrestling with wire that big. I use welding cable for my big stuff (1/0, 2/0) because it is more flexible.

[scottz]

Originally Posted by Ctopher61

Was thinking the same thing. Number 2 wire sounds like it might create more resistance than anything else. Just my thoughts, without taking pencil to paper and doing a calc.

The bigger the wire, the less the resistance; if you have the muscle to handle it.

[rohrmann]

You could really upgrade to a system like this rig has, that is a 20,000 watt lithium battery and 2,100 watts of solar. Of course, the rig starts at $1.7 million, but who's counting? https://www.yahoo.com/news/1-7-milli...134600242.html

[scottz]

Originally Posted by rohrmann

You could really upgrade to a system like this rig has, that is a 20,000 watt lithium battery and 2,100 watts of solar. Of course, the rig starts at $1.7 million, but who's counting? https://www.yahoo.com/news/1-7-milli...134600242.html

Expecting to see you roll up to Quartzsite in one of those.

[PNW Fireguy]

Originally Posted by Sparky55

Yes. I simply disconnected the red and black 12v converter wires and tape them off. You can also disconnect the 120v circuit to the converter/ charger and tape them off as well. I left the charger in place in case something ever goes wrong with the victron invert/charger unit. I could reconnect the previous charger in emergency.

Just remove the reverse polarity fuses much easier. If you want to reuse insert them.

[E12Cheng]

Just pull the fuses should work fine I will do that. Here is an update on today’s work. I installed the inverter and dc buss work along with the charge controller.

[rohrmann]

Originally Posted by scottz

Expecting to see you roll up to Quartzsite in one of those.

Besides not being real fond of Fords after driving them for at least my last 25 years at work, it looks like there is a two year lead time to get one, plus it's a bit pricey. Don't even want to guess what the payments would be. And Becky would not like the bed location. Looks like one of these would work for a younger camper with lots of spare cash. And, for just the power system, how much would one of those batteries cost and weigh?

[Sparky55]

Good idea. But I think I would disconnect 120v feed into the charger. I believe that the charger transformer could still be wasted energy when the inverter is energized to the 120v sub panel even when the 12vdc fuses are pulled. Correct me if I’m wrong?

[PNW Fireguy]

The PD converter and charger are a single integrated unit.