Solar Panel Wiring

[CMORGANSKOOL]

Rich solar poly 12v 100 w panels are down to $80 on amazon now.
https://www.amazon.com/Richsolar-Pol...s%2C137&sr=8-4

[o1marc]

Originally Posted by CMORGANSKOOL

Each 12v panel in series increases the voltage by 12v so 2 would be 24, 3 36, 4 48 and so on, but you have to match the voltage to the controller, like some are just 12v mine is 12 and 24, and you have to match the voltage to the battery bank so if you have 24 volts you need two 12v batteries wired in series and a 24 volt inverter. The benefit of using 24, 36, 48 volts is you have lower amps and can run smaller gauge wire. 2 100w 12v panels in parallel are 16 amps. 2 12v 100 watt panels in series is 8.3 amps. 12v systems require 0ga, 4ga or 6ga wire depending on load to carry the current. You want the panels as close to the charge controller as possible, and the battery bank as close to the controller as possible and the inverter as well. I have a 3 ft run from the panels to the controller and a 3ft run from the controller to the battery. 12" from the battery to the inverter. The easiest way to set it up is to mount the inverter, controller and fuse box on a board or square of plywood. Ideally you want a fuse and switch between the panels and the controller and a fuse between the controller/battery bank, fuse battery/inverter. and a breaker between the battery and inverter

https://www.amazon.com/InstallGear-G...gateway&sr=8-3

https://www.amazon.com/ZOOKOTO-Circu...s%2C131&sr=8-7

Rate your fuses based off the load. 8.3 amp per 100 watts of power for the panels, and your battery is probably 100 amp. If you have a 200 amp draw inverter like mine you need two 100 amp batteries to power it.

I've got a 15a breaker between the panels and the Victron MPPT100-50, 12v/24v. I have a 100a breaker between the batteries and the MPPT positive.

[CMORGANSKOOL]

That looks great. You don't need the breaker between the controller and the battery, just between the battery and the inverter. You'll never get reverse flow to the controller, but you want to be able to shut off the line to the panels to work on the battery bank or the controller, and have an over voltage protection in case the panels try to fry your controller, so that's all exactly right. Your inverter could try to fry your battery so I'd move the breaker to the battery/inverter + connection provided the inverter only draws 100amp max, you may need a bigger one. That looks like a big ass inverter!! I have a 600 pure sine that I have wired for small electronics and small loads, and a 2000/4000 whistler for power tools. The big inverter draws a lot of current just doing nothing. You may want a tiny one for the lights and such and the big one for vacuuming and microwaving.

[o1marc]

Originally Posted by CMORGANSKOOL

That looks great. You don't need the breaker between the controller and the battery, just between the battery and the inverter. You'll never get reverse flow to the controller, but you want to be able to shut off the line to the panels to work on the battery bank or the controller, and have an over voltage protection in case the panelshttp://xlforum.net/vbportal/forums/showthread.php?t=1538950 try to fry your controller, so that's all exactly right. Your inverter could try to fry your battery so I'd move the breaker to the battery/inverter + connection provided the inverter only draws 100amp max, you may need a bigger one. That looks like a big ass inverter!! I have a 600 pure sine that I have wired for small electronics and small loads, and a 2000/4000 whistler for power tools. The big inverter draws a lot of current just doing nothing. You may want a tiny one for the lights and such and the big one for vacuuming and microwaving.

The red on/off breaker goes between the batteries and the inverter. This inverter is a 3000/6000. The red and black 2/0 wire going down go to the inverter in the garage that is a 3500/7000.
I will start with 6-100w panels, with room to expand to 10-12 if needed. I have 2 existing batteries, plan on at least one, maybe 2 more. All 100AH.

[o1marc]

Originally Posted by CMORGANSKOOL

https://www.amazon.com/InstallGear-G...gateway&sr=8-3

https://www.amazon.com/ZOOKOTO-Circu...s%2C131&sr=8-7

Rate your fuses based off the load. 8.3 amp per 100 watts of power for the panels, and your battery is probably 100 amp. If you have a 200 amp draw inverter like mine you need two 100 amp batteries to power it.

I have 4 of the plastic fuse boxes you linked, they are all 250A. I have 3 of the expensive ones in the second link, 30, 50, 100A. The diagram I am using shows an 80A breaker or fuse between the batteries and the CC.

[o1marc]

I'm guessing with what I've read, having a MPPT charger won't matter if they are set in parallel or series. I'm running 10g wire, so that's not an issue. I have all I need to go ahead and wire them today. Crimpers won't come for at least a week, so I'll crimp with what I have. Parallel or Series?

[CMORGANSKOOL]

Read your controller specs. Mppt prefer higher voltage so series connect panels will give you a better charge profile but are only good in full sun. If one of your panels is shaded you’ll get 0 power. Most people use a mix of series and parallel panels. If you shade a parallel panel the second panel continues to provide full power. Just be careful. The controller amp rating is for amps out not amps in. For example my 30amp controller can run up to 50 volts in and 30 amps out. When you run your panels in series and have say 40 volts in the controller converts it to 12v and the amps increase. For example my 2 100w panels are 8 amps in series at 24 volts but create 16 amps out when converted back to 12v. If I had 3 100w panels in series at 30 volts they would make 10 amps in but 25 out. Hope that all makes sense.

[o1marc]

I have the system up and working. I have 4 -100w panels in parallel.All neg/neg, and pos/pos. I need a bunch more "h" connectors to add the other 6 panels. Running through a Victron MPPT 100/50 controller.

Editted, not series, wired in parallel

[CMORGANSKOOL]

Everyone loves those charge controllers. You are going to be thrilled with that setup. 1000 watts is a good amount of panels.

[CMORGANSKOOL]

The manual says you’re right in spec with 1000 watts in series. Just be aware you’re running 83 amps through those 10ga wires.

1000w/12v =83 amps.

[CMORGANSKOOL]

The chart says you should be running 4ga wire for up to 30’ run at that amperage


Amazon has it cheap. Just got some.
SoundBox Connected 4 Gauge Red /... https://www.amazon.com/dp/B01M6YNIS9...p_mob_ap_share

[o1marc]

Originally Posted by CMORGANSKOOL

The chart says you should be running 4ga wire for up to 30’ run at that amperage


Amazon has it cheap. Just got some.
SoundBox Connected 4 Gauge Red /... https://www.amazon.com/dp/B01M6YNIS9...p_mob_ap_share

It's only around 15'.

[TheHubbardBus]

First off, your 100/50 controller won't support 1000W of panels. You'll either need a larger controller or another 100/50 in parallel to run that many panels.

Second, even if it did, wiring all your panels in series would exceed its max input voltage. And even if it didn't, doing so would provide poor performance if even one panel out of 10 was shaded.

Third, on the other end of the spectrum, wiring ten 100-watt, 12V panels in parallel would both defeat the benefit of the MPPT in the first place, as well as require a ridiculous wire gauge to handle the equally dangerous amperage you'd be trying to route through your roof.

Fourth, even if you ignored this advice, the CCA sound-system cable linked to above is neither copper (copper clad ALUMINUM), nor is it 4AWG (read the fine print). So it would not be suitable for handling the 85 amps or so you should never be running through it anyway. I doubt the insulation would be up to the task even if it was.

if you must stick w/ the 100w/12v panels, then you'd probably do best to run 2 parallel strings, each consisting of 5 panels in series. nominal voltage would be ~60V, which would be within the limits of your controller(s), as well as reasonably safe, and you could then use much-more-reasonable 14awg (so long as it's actually copper). Then again, if you only plan on having 400AH of total storage, 1000W of panels is probably overkill.

Your inverter is way too large compared to your anticipated battery bank, which means when it's not in sleep/standby (if it even has a standby mode), it will be burning up amps you can't really afford to lose. It's also far larger than ideal for your system voltage. Even at 3000W - the continuous power rating, not the peak - you're looking at ~250Amps... 4/0 cable bare minimum. The higher in amps you go, the more critical everything becomes... every wire run, every connection, everything. And the more disastrous the potential consequences if something goes wrong. Running big DC amperage is an accident waiting to happen.

The only good reason for running a 3000W inverter is if you intend on running 3000W peak loads. 3000W... 250 amps @ 12V ... almost surely exceeds the max safe discharge rate of your 2 100Ah batteries. Even with 4 (paralleled - another less-than-optimum design decision), for a total of 400AH, you're still going to be putting so much of a strain on them at that discharge rate that you'll significantly shorten their lifespan, even if you're only running that wattage every now & then.

Basically, your system is all out of balance. You've got too much panel planned for your bank, too much panel planned for your controller, too little bank for your inverter, and too much inverter for your system voltage.

I don't mean to rain on your parade, but I honestly believe you're either going to end up with a system that doesn't perform as you hoped, a safety hazard, or both. What the 'fix' is depends on your needs. If you need to pull 3000W peak off your battery bank, a lot is going to need to change. If not, replace the 3K inverter with a 1K, limit your panels to 6 (4 is a good start, and may be all you need. 2 strings either way would probably work best), and when your current battery bank dies, replace it with a single string of 6x2Vs, or 2 strings of 2x6V. Limit high-amp stuff to shore power/generator input only, on dedicated circuit(s).

[PNW_Steve]

Originally Posted by TheHubbardBus

First off, your 100/50 controller won't support 1000W of panels. You'll either need a larger controller or another 100/50 in parallel to run that many panels.

Second, even if it did, wiring all your panels in series would exceed its max input voltage. And even if it didn't, doing so would provide poor performance if even one panel out of 10 was shaded.

Third, on the other end of the spectrum, wiring ten 100-watt, 12V panels in parallel would both defeat the benefit of the MPPT in the first place, as well as require a ridiculous wire gauge to handle the equally dangerous amperage you'd be trying to route through your roof.

Fourth, even if you ignored this advice, the CCA sound-system cable linked to above is neither copper (copper clad ALUMINUM), nor is it 4AWG (read the fine print). So it would not be suitable for handling the 85 amps or so you should never be running through it anyway. I doubt the insulation would be up to the task even if it was.

if you must stick w/ the 100w/12v panels, then you'd probably do best to run 2 parallel strings, each consisting of 5 panels in series. nominal voltage would be ~60V, which would be within the limits of your controller(s), as well as reasonably safe, and you could then use much-more-reasonable 14awg (so long as it's actually copper). Then again, if you only plan on having 400AH of total storage, 1000W of panels is probably overkill.

Your inverter is way too large compared to your anticipated battery bank, which means when it's not in sleep/standby (if it even has a standby mode), it will be burning up amps you can't really afford to lose. It's also far larger than ideal for your system voltage. Even at 3000W - the continuous power rating, not the peak - you're looking at ~250Amps... 4/0 cable bare minimum. The higher in amps you go, the more critical everything becomes... every wire run, every connection, everything. And the more disastrous the potential consequences if something goes wrong. Running big DC amperage is an accident waiting to happen.

The only good reason for running a 3000W inverter is if you intend on running 3000W peak loads. 3000W... 250 amps @ 12V ... almost surely exceeds the max safe discharge rate of your 2 100Ah batteries. Even with 4 (paralleled - another less-than-optimum design decision), for a total of 400AH, you're still going to be putting so much of a strain on them at that discharge rate that you'll significantly shorten their lifespan, even if you're only running that wattage every now & then.

Basically, your system is all out of balance. You've got too much panel planned for your bank, too much panel planned for your controller, too little bank for your inverter, and too much inverter for your system voltage.

I don't mean to rain on your parade, but I honestly believe you're either going to end up with a system that doesn't perform as you hoped, a safety hazard, or both. What the 'fix' is depends on your needs. If you need to pull 3000W peak off your battery bank, a lot is going to need to change. If not, replace the 3K inverter with a 1K, limit your panels to 6 (4 is a good start, and may be all you need. 2 strings either way would probably work best), and when your current battery bank dies, replace it with a single string of 6x2Vs, or 2 strings of 2x6V. Limit high-amp stuff to shore power/generator input only, on dedicated circuit(s).

Solid advice!

One note: your existing charge controller will support 1000 watts of panels if you go with a 24 volt house battery bank.

[CMORGANSKOOL]

Originally Posted by CMORGANSKOOL

The manual says you’re right in spec with 1000 watts in series. Just be aware you’re running 83 amps through those 10ga wires.

1000w/12v =83 amps.

Upon further manual reading although you can run 100v in your 1000w 12v in parallel do exceed the charge amperage at 83amps. If you run the panels in series you are within spec on the charge input but you will exceed the charge amperage when it converts to 12. It says you can run 700w parallel panels and 1400 in series but 1400 still exceeds the amps out by 70 amps.
You should call Victron to confirm otherwise you’ll trip the over voltage sensor and it won’t work. Looks like you need a second controller or a larger one to handle to panels. However if Victron says you have 1400 watts in series then you’re ok. When the manual says 1400 watts I think they’re referring to house panels at 40 volts. 1400w/40v is 35 amps.
https://www.victronenergy.com/upload...R-DE-ES-SE.pdf

[gs1949]

This is a very interesting thread. Thanks to everyone who has posted so far.

[TheHubbardBus]

Originally Posted by CMORGANSKOOL

Upon further manual reading although you can run 100v in your 1000w 12v in parallel do exceed the charge amperage at 83amps. If you run the panels in series you are within spec on the charge input but you will exceed the charge amperage when it converts to 12. It says you can run 700w parallel panels and 1400 in series but 1400 still exceeds the amps out by 70 amps.
You should call Victron to confirm otherwise you’ll trip the over voltage sensor and it won’t work. Looks like you need a second controller or a larger one to handle to panels. However if Victron says you have 1400 watts in series then you’re ok. When the manual says 1400 watts I think they’re referring to house panels at 40 volts. 1400w/40v is 35 amps.
https://www.victronenergy.com/upload...R-DE-ES-SE.pdf

You don't have to read the manual. You don't have to call Victron. All you have to do is read the spec sheet. 100V nominal input max. How you arrange your panels makes zero difference. If they're putting out 100V+ in whatever configuration you've come up with, you're doing it wrong.

But, as I mentioned above, this is a moot point, because there's absolutely no good reason to run ten 100W 12V panels all in series, nor all in parallel, and in neither case can the charge controller support that wattage in panels on a 12V bank anyway, making this moot point even 'mootier'.

The goal is to keep the amperage in a range that keeps your wire size / voltage drop reasonable, the amperage safe, and the voltage in a range that is also safe, within the limits of the charge controller, significantly above the battery bank voltage, but not so much that efficiency drops off.

That controller will support a max of 6 100w/12v panels w/ a 12V bank, which should either be 2x3 or 3x2, providing (respectfully) ~36V/17A, or ~24V/25A nominal. 14awg copper for the former, 12awg min for the latter (assuming 75-degree rated wire and no temp/conduit derating).

Those are really the only reasonable choices with a 12V bank and the components the OP is using.

[o1marc]

If I swap my 3-27dc batteries for GC2's would I better off with 3 or 4 of those?

[TheHubbardBus]

If a GC2 you're referring to is like the one I just looked up... 6V/215Ah... you're not really buying yourself much difference in AH capacity over what you planned originally. You're just reducing the number of parallel runs for the same capacity. 2 strings of 2 batteries each (4 total) would give you 430AH. Reducing the number of parallel strings is a good thing, so you're much better off than you were w/ 4 12Vs. But I'm not sure that's going to be enough bank to make you happy. If you wanted more, you'd either want to use 4 larger 6V batteries, or switch to 2Vs.

We still don't know what your power needs are, what your battery budget is, how much space you have for batteries, etc. We don't even know what your peak watts will be, which will determine your ideal system voltage.

IMO The very first step should be listing every single electric appliance you hope to use, figuring out how many amps each draws (either product documentation, estimates based on similar products, or testing w/ a kill-o-watt), estimating how much time you'll be running each item per week, and adding up the amps of every one of those items that you foresee yourself operating at the same time in order to determine your anticipated max amp draw. Then you do the math, realize your expectations were completely unrealistic, do the math again, rinse & repeat, and eventually come up with a compromise you can live with

Alternatively, and this is probably a descent gambit for you if you don't want to wade too deep in these waters:

Keep the 6 panels and CC you've got. Don't plan on buying any more, at least not now. Run them 2x3 or 3x2. Replace the 3000W inverter w/ a quality inverter/charger with AC pass-through in the 1000-1500W range. Plan on powering only singular loads < 1000W off your bank. Any of the big stuff... large microwaves, hair dryers, space heaters, particle colliders... are run off shore or generator power only (transfer switch -> dedicated circuit(s)). With reasonable peak loads you've limited yourself to w/ the smaller inverter, you can probably get by with the 400AH bank (GC2s) discussed above, but if your budget/space/etc allow for it, shoot for 600-800, either using larger 6vs, or better yet, a single string of 2Vs.

I can't say whether the above example will meet your needs or not. But all the components would work together, your wire runs would be reasonable, your risk of fire/electrocution/impromptu arc-welding would be greatly reduced, and it will work to power many items well... anything above what's it's capable of... that's what the generator(s) are for.

[CMORGANSKOOL]

Originally Posted by o1marc

If I swap my 3-27dc batteries for GC2's would I better off with 3 or 4 of those?

My dad got very limited life out of lead acid deep cycle batteries in Hawaii on his solar setup. Like 1 year of cycling daily. You should do a load test with a monitor and your 3000w inverter and see how long it runs. Once those batteries die look into LiFePo4 or Agm batteries. I bet your three batteries can run all your lights and electronics ok for 12 hours.