• Have you tried out dark mode?! Scroll to the bottom of any page to find a sun or moon icon to turn dark mode on or off!

diy solar

diy solar

not certain what I'm looking for

blenderbender

New Member
Joined
Jan 27, 2023
Messages
81
Location
Western Pennsylvania
I'm a lot confused about what I'm looking for in a controller/inverter. I have (8) 12v 100ah batteries, and (20) 400w/500w bifacial panels. The following are the parameters I'm considering attempting to satisfy:

(1) supplying an Ag building/shop/modest living quarters with a good portion of my electrical needs

(2) I'd like to have 120vac for all the normal stuff and 240vac for a welder, and air compressor that's used only occasionally.

(3) I also have a 10kw NG backup generator which I'd like to be able to incorporate into the system if feasible.

(4) I don't think I have any interest in tying into the grid. I figure, perhaps mistakenly, that all I need is a transfer switch to swap between the grid
and solar as required.

I do have competent resources to help me with all the normal electrical stuff that is beyond me, but I am the one who is trying to learn all about the solar end of things. I've been immersed in trying to sort all this stuff out and figured I'd just ask if someone might chime in and steer me to the proper sort of controller/inverter I should be looking at. Not so much brand specific but type, features, etc. Thanks and Happy Holidays to all!
 
Knowing system requirements in max kW and worst case daily kWh requirements will help get specifics. The shortest day of the year here I produce about 1/3 the power I do in the summer, but in the summer I use 6 X the power to run two large air conditioners, so my Worst case kW requiremetn is 17 kW, and the daily kWh requirement wost case is 160 kWh. Needless to say, I do not have a system capable of off grid.
(2) 240vac for a welder, and air compressor that's used only occasionally.
With the motor surge currents, this ups the requirements quite a bit. Also will both these device be on at once?
(3) I also have a 10kw NG backup generator which I'd like to be able to incorporate into the system if feasible.
There's many systems that will let you incorporate a generator, with an inverter charger, but all will want you to have a generator bigger than your system. You might have a 6 - 7 kW mx usable continuous output, and going over that could overload a generator.

Not knowing specs, the air compressor and welder could put you over this limit.

If this is a factor, you could get an AC to DC converter that will turn the AC into DC and charge the battery directly. The only reliable converter in a higher kW ratign I know of is an EG4 chargeverter, and those can be paralleled.
 
Knowing system requirements in max kW and worst case daily kWh requirements will help get specifics. The shortest day of the year here I produce about 1/3 the power I do in the summer, but in the summer I use 6 X the power to run two large air conditioners, so my Worst case kW requiremetn is 17 kW, and the daily kWh requirement wost case is 160 kWh. Needless to say, I do not have a system capable of off grid.

With the motor surge currents, this ups the requirements quite a bit. Also will both these device be on at once?

There's many systems that will let you incorporate a generator, with an inverter charger, but all will want you to have a generator bigger than your system. You might have a 6 - 7 kW mx usable continuous output, and going over that could overload a generator.

Not knowing specs, the air compressor and welder could put you over this limit.

If this is a factor, you could get an AC to DC converter that will turn the AC into DC and charge the battery directly. The only reliable converter in a higher kW ratign I know of is an EG4 chargeverter, and those can be paralleled.
Thank you for your input, though some of it (chargeverters) I don't yet understand clearly. I just got a book in the mail and obviously I need to bone up quite a bit. Bottom line is I bought a bunch of batteries and a bunch of panels without knowing what I was getting into. I was reacting to low prices, which by all accounts may not last if the Trumpian tariffs are going to be in place anytime soon. I'll sort it out..... eventually. But I'm happy to have found this forum.
 
I have (8) 12v 100ah batteries,
Bottom line is I bought a bunch of batteries
Lithium or lead acid or ??

Your battery bank pretty much needs to be 48V so it is unfortunate that you bought 12V batteries. Connecting in series (4S3P or 3P4S) is suboptimal as balancers will likely be needed.

8 x 12.8V nominal x 100Ah = 10,240Wh (10.2kWh) ... 50% usable if lead acid makes 5,120Wh

Depending on what your daily kWh amount is, you will be able to see if you have enough battery to get you through the ~20hours a day without quality solar production.
 
If you want to run a welder, which would be a few thousand watts, you should plan to build your battery bank for 24v or 48v. While you could do it at 12v, the battery cable size would be large and expensive.
 
Need to start looking at the specifications for all the things you need and make sure they work together before you buy anything. For example your 20 PV panels will have Voc, Vmp, Isc and Imp specifications. How you connect them up determines if the specifications for your SCC (MPPT) is sized correctly. How you hook them up gives you the parameters for sizing your PV wire feeding the SCC. The SCC can be incorporated into an AIO (All in One) but is separate if buying a components system with a inverter or inverter/charger.

Your selection of an AIO or inverter will depend on if they can power your needs. Knowing that will require doing an audit or simply hoping that you picked right. Some AIO's can be paralleled or stacked to produce higher outputs. This means that if you get this type and find you need more power your can add another in the future.

Look through the Forum at other folks reviews of their setups to see if you can glean ideas. Also Will's videos ( see the top of the Forum the DIY Solar Videos link) are handy for folks starting out.
 
If you are only doing heavy welding occasionally, it might be worth just running that from the generator instead of the battery pack.
 
Too late for other batteries.... they are LiFePo4. As per the welder, it can run on 120 most of the time. i'd only need 240 on occasion for heavier welding.
Note, many 12v LiFePo4 batteries can be put in series to make 24v or 48v banks. Look at the specs for series connections to make sure the BMS is rated for series. If you are under 3000w, it is not such a big deal.....with the cable and connector sizes.
 

diy solar

diy solar
Back
Top