opinion on setup?

[rtpassini]

This is for a cabin up north. weekend use.
I will have 9 panels (was going to use 6, but we have more) rated at 50 watts ea. 22.1 volts open circuit. 18.2 rated. current 2.75 amps. they are solarworld sunmodule sw50polyRMA all new. my wife got them for a great deal when she worked on solar systems at a very large scale where she used to work. So we will use them until they go bad.
I was going to series wire them with 10 ga. but think I will go parallel. its about a 25-30 foot run to the controller. if i do parallel then it would be 4 ga after the panel connections
the controller is a Renogy Rover elite 40 amp mppt https://www.renogy.com/rover-li-40-a...er-back-order/
inverter is a pure sine 3000 watt renogy https://www.renogy.com/3000w-12v-pur...wave-inverter/
batteries will be 4 trojan sagm 12 135. (most likely, waiting to hear from one other brand)
our stove and fridge run on propane. the only "normal" usage will be tv, led lights and fans (ceiling, small other circulating fans and chargers etc)
my inlaws have a much much smaller setup and they have ran regular maintenance free batteries and they usually get a good 2 days out of theirs without problems their batteries last about 5 years on average. So I figure this setup should work very well but wanted to hear opinions.
Do I have all my wiring etc proper? rest of the items? Thanks for any feedback

( Moderator note - have you asked this same question before, here ? )

[rtpassini]

To Mike90250, no I havent asked or posted before. Brand new to the forum

[Sunking]

9 panels I will go parallel. 450 watts
controller is a Renogy Rover elite 40 amp mppt
batteries will be 4 trojan sagm 12 135.
inverter is a pure sine 3000 watt renogy )

Well you have done just about every thing wrong from the start to end.

1. Wire your 9 panels in series negates all the benefits of using MPPT. Your only configuration option is 3S3P.
2. Since you opt to play with toys, 12 volts toys, with 450 watts will max out your controller with no growth potential. same controller at 24 volts can grow to 1000 watts and @ 48 volts up to 2000 watts. You are stuck with a 12-volt toy at 500 watts max.
3. Never ever parallel; BATTERIES. With 4 in parallel you will surely be replacing them every year.
4. To to thing off you make a large fire hazard using 12 volt toy at 3000 watts. limit 12 volt inverters to no greater than 1000 watts, and your Inverter should be no larger than your panel wattage.

So your plan is perfect, I say gofferit.

[rtpassini]

1) why is my only option 3s3p?
As i read, "Strictly series connections are mostly utilized in smaller systems with a MPPT Controller. Connecting your panels in series will increase the voltage level and keep the amperage the same. The reason why series connections are utilized with MPPT controllers is that MPPT Controllers actually are able to accept a higher voltage input, and still be able to charge your 12V or more batteries. Renogy MPPT Controllers can accept 100 Volts input. The benefit of series is that it is easy to transfer over long distances. For example you can have 4 Renogy 100 Watt panels in series, run it 100 feet and only use a thin 14 gauge wire."

2)why is my controller being maxed out at 450 watts?

3) why can you not parallel batteries to increase the Ah? what causes them to burn out every year?
and just because its 3000 watts doesnt mean im drawing or going to be maxing it out. My normal usage is about 300 watts.

[Mike90250]

1) why is my only option 3s3p?

Because as you increase panel voltage, your MPPT conversion efficiency drops. And 9 panels in series will overvoltage your controller instantly.
22V x 9 panels = 198V
22v x 3 = 66V

As i read, "Strictly series connections are mostly utilized in smaller systems with a MPPT Controller. Connecting your panels in series will increase the voltage level and keep the amperage the same. The reason why series connections are utilized with MPPT controllers is that MPPT Controllers actually are able to accept a higher voltage input, and still be able to charge your 12V or more batteries. Renogy MPPT Controllers can accept 100 Volts input. The benefit of series is that it is easy to transfer over long distances. For example you can have 4 Renogy 100 Watt panels in series, run it 100 feet and only use a thin 14 gauge wire."

2)why is my controller being maxed out at 450 watts?

50W x 9 = 450w system @ 13V charging = 34.6A coming out of the 40A charge controller. You are about at the max limit.

3) why can you not parallel batteries to increase the Ah? what causes them to burn out every year?
and just because its 3000 watts doesnt mean im drawing or going to be maxing it out. My normal usage is about 300 watts.

Batteries in parallel seldom, even under the best conditions, equally share the loads. One string is always "better" than the other 3 and will work itself to death while the other 3 are idle. At some point, another string becomes "better" and the race to the bottom is on. see :
http://www.smartgauge.co.uk/batt_con.html for the details and how to ameliorate a lot of the problem

A 3,000W inverter will likely consume 50W or so, just being turned on. Read the idle power spec for your 12V inverter. below is the self consumption for a house sized 6,800w, high quality inverter, which at 28w is much more efficient than many large 12v inverters. if you only need to consume 300w, you don't need larger than 600w inverter.

Conext_XW_spec_Excerpt.png

[rtpassini]

makes sense. thanks for the clarification.
Easy tweaks. I run series parallel for the panels.
and order a 24 volt inverter.
then I can just switch the batteries to a series parallel wiring configuration correct?
then everything is running at 24 volts. and its a more efficient setup?

[rtpassini]

as a side note, if someone runs a 12 volt system (which lots still do) then they cant run more than one battery?
after looking at your link, its not that you CANT do it. Its that there is a CORRECT way to wire in parallel and achieve more equal balancing.

[Mike90250]

24V would make more sense, and leave you more room to grow the system later, from 450W to 900W

wiring panels in 3S3P is still the best config for your 9 panels & controller, but you could add more strings of 3 in parallel, or change to 4S4P, but 4S is your limit to not fry your controller.
It's possible to get to a 48V bank if needed, but you might be pushing the limit of the controller to downconvert 80V to 65V for EQ on the battery bank, you would have to read the specs for the controller to see what voltage it needs for it's "overhead" to charge a 48V bank. 48V banks can sometimes need 65V to run the EQ cycle.

And right, there are better ways to achieve more equal load sharing in the battery bank, but it's very conditional to all connections and crimps being perfect and identical, so there is not a high or low resistance path, you want all paths to be the same.

[chrisski]

Brand new and still putting together my first system.

Already mentioned in the first reply, but when I see 4 Batteries at what I think is 135 amp hours each, this seems way underpowered to run a 3000 watt inverter. So without crunching numbers, the panels you mentioned getting might be good for a 1000 watt or under inverter, which means you might be able to run a single serve electric coffee maker safely, as long as you do this a couple of times a day. With twice that battery power, perhaps you can run a 1.7 liter electric kettle, but that could also be dangerous. To run one of those things I mentioned, and perhaps watch TV at the same time, might need about four times the battery power and a 48 volt system. There's plenty of YouTube videos out there that have larger inverters on small systems which is what I wanted to do until I came here and got educated. I started noticing things like when the hair dryer is turned on with the 1500 watt inverter with 700 watts of panels and a 400 amp hour battery bank, the voltage drops by one full volt goes from high 12s to high to mid 11s. That is a battery pushing itself beyond its limits creating heat.

Once I get my system put together, I expect if I used it daily, which I won't I'd be paying 4 to 5 times the rate of line power from the electric company. Since I use it less, my savings will be even less. The system I'm putting together will be a 12 volt with 600 watts of panels, and I doubt I will use any high energy devices like a single cup coffee maker with this. I'm watching what I get so I can expand to 24 VDC, but I'm kind of stuck at the RV is already wired for 12 Volts to all DC appliances to include the lights and brakes.

There's a bunch of things that look like off the shelf kits to solar power your cabin or RV, but once you really look at them, they run far short, or even dangerous.

[Saggys]

I have an oversize 12 volt system that according to some should have exploded and caught fire by now but it has been running without problems for four years at this time. It can be done, and the only reason I did it was I purchased the equipment for pennies on the dollar. I even have batteries in series parallel being charged by a Mercury displacement relay. Careful attention to detail for cable size and voltage drop is necessary to pull it off. If I had to do it over again I would have gone 48 volts, much more flexibility in future design. If all you have is 12 volt equipment and not a lot of money you can build a functional system. Solar in it's early days had plenty of 12 volt systems.

[Fordtrucksforever]

A bunch of great information on this thread here. Am I right that you were planning to keep your system at 12 volts originally? One thing I see is the limited amount of solar panel you have. It would be difficult to expect anything close to the 300 watts of use without draining your batteries. After dark, you will put a lot of load on them, unless keeping close tabs on amp load. Otherwise your batteries may not make it much past their warranty. Your 450 watts of panels will be lucky to put out half that amount of useful power. Any parasitic drain from your controller or inverter will just make things worse. This is just my opinion. You may get lucky. Especially if your place is close to the equator.

[rtpassini]

Checking in. Weve been up and running a couple weeks now. I currently have them 4s4p. My charge controller usually tops out around 70 volts and 22 amps. However I do notice even when bringing in 60 volts it sometimes only has 5 amps or less. Sometimes as low as 2 amps. The amps really seem to bounce around. Its been so hot we run the generator to power a.c. but 2nd night in I'm usually around 12.5 volts on my batteries. Mornings Will drop to 11.9. Then the morning sun hits and hovers around 12.2. Would changing to a parallel wiring foe the panels help keep my amps coming in up? And charge the batteries faster?

[chrisski]

Appears the charge controller maxes out at 40 amps, with 16 panels if you went from 4S4P to 2S8P, you would see around 44 amps, which is more than the charge controller can handle. since your at 70 volts at 22 amps max, doing the 2S8P configuration would get you about 35 volts and 44 amps.

Still starting my first system, so you’re farther than me, but you may want to read the battery stickies for the one on how to test them with a hydrometer, and look at each battery and each cell to determine health.

Your numbers, do they come from the charge controller? Or from a Battery monitor?

[rtpassini]

I have 8 panels total. Numbers are from controller. Thats why I'm taking them with a grain of salt

[chrisski]

I have 8 panels total. Numbers are from controller. Thats why I'm taking them with a grain of salt

If its 8 panels, is it 4 in series with 2 parallel strings? If you are and went 8 in series, I would still think the 40 amps would be exceeded.

Anyway, the MPPT is supposed to take whatever amps and voltage are thrown at and as long as you don’t exceed the 100 volt rating or the 40 amp rating, the controller would convert it.

My guess is if you had a battery monitor, you would see the 22 amps used to 40 amps as it changes the voltage to that of your batteries,

Also, if the max output of the controller is 40 amps, then it might not be properly sized for the panels. If you were seeing 22 amps into the controller, then it probably could convert 70 volts at 22 amps to close to 50 amps at 24 VDC to charge the batteries, but the charge controller is limited to 40 amps out.