Bah20018: Help setting up new off solar+battery system

System · October 2016

This discussion was created from comments split from: Max panel wattage input to Charge Controller.

Bah200018 · October 2016

Hi, I currently am in need of assistance. I have 48 panels, some the same, but most different. All are 12v panels. That said, I have 66 sunsaver 6a12v charge controllers. The combined wattage on my panels is 3kw conservatively. I want to run this to a small room outside my home wich houses my soon to be battery bank and that is 10 agm powersonic 100ah batteries. Now the problem I am having is if I run all panels in parallel then the voltage remains the same, but the amperage increases this will give me a total of about 150a at 17.8v max. And I would have only two wires to run through a brick wall. My question here is if I do this, can I run multiple charge controllers off the two wires, kinda like a distribution block method so to speak?

BB. · October 2016

Bah200018, welcome to the forum and I moved your post to your own thread...

In general, yes you can do what you ask. Specifically, I would not recommend this--It is going to be a pain to maintain and debug the system as it ages and things go wrong.

First--A 1,000 AH 12 volt AGM battery bank with 12x AGM batteries in parallel can be problematic. It requires extra work to wire the bank safely (ideally, a fuse or circuit breaker per battery) and properly to get good current sharing.

For the charge controllers--You are better off getting a larger 60-80+ amp charge controller and connecting your array in series parallel (which is an issue if you do not have all identical panels).

And for large AH battery banks, you need lots of heavy copper cabling for charging current and to support your loads (which you have not discussed yet). That size battery bank is a perfect candidate for 24 or 48 VDC battery bus.

I guess you have a 12 VDC input AC inverter picked out (or already purchased)?

My suggestion is to stop buying anymore and step back--Tell us about your loads/energy needs, roughly where the system will be installed (nearest major city). And what your expectations are (off grid home, save some money, emergency backup, going green).

-Bill

Bah200018 · October 2016

Pardon the late reply. Yes I do need to provide more info. First. This will be installed on my awning over my hot tub. The area it's going on is 8x27ft with a 3 degree pitch south to north. The panels are all different because I have bought them from an oil company contractor who upgraded their automation equipment. Basically 10 100ah batteries, and sticker value on all panels 3.2kwh in power. The charge controllers he threw in. All for a whopping 575$ that's all I'm actually getting from him.
Now for where.. they will be in lubbock tx. Super hot summers, mild winters. Now as to why...I just received a 680$ electric bill a few months ago. I wanna knock that down significantly. Here is the kicker, local power company will make me sign an interconnect agreement, plus make me purchase ( not lease) a net meter, I have to have a certified electrician do the work, I have to have codes pass the inspection on the structure before I put the Panels on, and after local Company ( can I really get in trouble for naming names???) Has the right to inspect my equipment at any time. Same guy then tells me...however it's your house, do whatever, if your not connected to the grid no one can stop you. It's all your own stuff....dun dun dunnnnnnn ( cue the suspense music) and here I am. I'm not a expert but I have tried to look things up the best I can. This got very very complicated really quickly. I don't even know if what I have is enough to make a huge difference...I wanted enough power to place a thermal air conditioner in my main living room thus causing my central unit not to run as much. And at 5 tons, that thing eats up electricity fast lol. I wouldn't know where to begin in terms of 24 volt or even higher I can manage 12v, or at least I thought anyway. After the prior comment ^^^^now I'm not so sure

BB. · October 2016

On your power bill, what is the kwh per month?

On general, spend money (and time) on conservation. Insulation, summer shading of roof, Windows, stuff. Check your energy consumption with a kill-a-watt meter for small loads and a whole house meter like The Energy Detective (and similar brands).

Figure out if new hvac system (like mini splits), lots of insulation, changing to leds, laptop computers, etc. will save money...

Next, grid tied solar is, many times cheaper than utility power. However, that option is going away (fewer solar subsides).

Of grid solar almost never saves you money. It can cost you 5 to 10x your present power bill. Batteries, inverters, chargers, panels, new batteries ever 8 years or so, new electronics every 10+ years, etc.

The chances the pieces you have still save you much money are slim. However, if you want a backup power, it could be ok (need to do paper designs first). The parts you have are fire a bunch of small systems. Sort of like trying to merge a bunch of VW bugs into a semi-truck. Not a good fit.

-Bill

Bah200018 · October 2016

So would it be better for me to sell the panels and buy all matching sets to work with?

BB. · October 2016

Maybe. The big thing is lead acid batteries age quickly if they are not kept charged.

Figure out their present state of charge and get them back to full. Below 75% state of charge, the sulfate pretty quickly.

The rest of the stuff, you can keep for more until you figure out what you want/need.

We don't want to waste your money or time.

If you can get good money for the parts, might be a good idea to cash out (may take some time to find the right buyer).

Otherwise, it will possibly just take us a few days to sort out the basics.

-Bill

Marc Kurth · October 2016

Depending upon the age and the brand, the batteries may be about gone.
What kind voltage readings do you see on each battery?

Bah20018: Help setting up new off solar+battery system

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