need to build a 24v solar system

[sherman647]

Hi, dears.
I saw one of the video that www. santansolar.com has used 250w solar panel for $50. it totally catch my sight and want to build a solar system for my shed.
the panel info is following
Rated Power: 250W
Open circuit voltage (VOC): 37.6 V
Max power voltage (VMP): 30.3 V
Short circuit current (ISC): 8.85 A
Max power current: 8.27 A
Power Tolerance 0/+3%
Maximum system voltage: 600V (UL)
Fuse Rating: 15 A
IP65 Junction Box w/MC4 Compatible Connectors
Frame: Anodized aluminum alloy
Weight: 41 lbs
Dimensions: 1650 × 992 × 35mm (64.95 × 39.05 × 1.37 inches)

First at all, i am planning to buy 10 of the solar panels
and buy 8pcs of 6 v batteries and wire them as the attachment.
my questions are:
1. What type of charge controller i need ?as i know 10 of panel means 2500w
it has {(37.6v * 8.85A) * 10}=3327.6watts/24V=138.65AMP so i need a charge controller over 140a and up, BUT,i can't find such charge controller at Amazon.com
ANY suggestion.?

2.as i want to build 24 V system, i need a converter, what large of converter I need.?

3. Can you figure out for me what else i need and what is your suggestion.?


Thank you for information
Very appreciate

 

[jasonhc73]

I used 4 of these panels on my cargo trailer.

Growatt or MPP-Solar make good 24v solar charge controllers.

Ten 250-watt panels, when brand new under test conditions would make 2500 watts.

Be happy with an average of 1600+/- 10% watts throughout the day with these used panels.

Another Cargo Trailer setup.

This is now officially a legitimate sickness. My 4th off-grid system: The players: This setup is actually cheaper than going with a PWM Hybrid all in one unit 48V unit. I have AC input to charge the 48V batteries with shore power. (The 21.99 charger) A way more than I will use MPPT battery...

diysolarforum.com

 

[rmaddy]

10 of those panels would need to be setup in either 5S2P or 2S5P. 10S is way too many volts and 10P is way too many amps. At both 5S2P and 2S5P you are looking at a max current at min temperature of over 113A. That's a massive charge controller.

You are probably better off using two charge controllers. Maybe 6 panels on one and 4 on the other. Then you can find two saner sized charge controllers.

And why build a 24V battery from 6V batteries? That's a lot of extra cabling and concerns about keeping it all balanced. Why not use four 12V batteries or two 24V batteries?

 

[Forbisher]

10 of those panels would need to be setup in either 5S2P or 2S5P. 10S is way too many volts and 10P is way too many amps. At both 5S2P and 2S5P you are looking at a max current at min temperature of over 113A. That's a massive charge controller.

You are probably better off using two charge controllers. Maybe 6 panels on one and 4 on the other. Then you can find two saner sized charge controllers.

And why build a 24V battery from 6V batteries? That's a lot of extra cabling and concerns about keeping it all balanced. Why not use four 12V batteries or two 24V batteries?

5S is way too much Voc for a 150V max SCC
Buy 9 panels for 3S3P on a 150V / 100A SCC

 

[rmaddy]

5S is way too much Voc for a 150V max SCC

5S works with a 250V SCC.

 

[Forbisher]

5S works with a 250V SCC.

Must be fun spending other peoples money. Haha.

 

[MichaelK]

Instead of buying 10 panels look at multiples of 3 or 4 instead. That is, buy 9 panels or 8 panels or 12 panels. Then you have more flexibility in your wiring scheme.

With 9 panels, you can wire in a 3S3P configuration. A 150V controller will work. With 8 panels you could wire either 2S4P or 4S2P. The later is how I have my workshop wired. That works for me because I have Midnight 200V controllers.

Twelve panels is getting into the 48V range, simply because you are producing so much power that even very large 24V batteries can't absorb that many amps.

 

[RJuelfs]

I plan to use 12 panels, with multiple controllers and separate arrays, pointed slightly different directions. This will also provide redundancy it something fails. Budget dictates the panels will all be purchased together to save on shipping, but the systems will be built separately, as funds allow. Still undecided if it will be 1 large battery or 2 stand alone systems. Probably 2 as to not mix different ages of batteries.
Hope that makes sense

 

[MichaelK]

Budget dictates the panels will all be purchased together to save on shipping, but the systems will be built separately, as funds allow.

Shop locally on Craigslist, or whatever similar venue you have. Then just drive over and pick them up. No shipping involved. I've been recently buying 245-260W panels for 55-62$ each. You can bring a voltmeter with you to test the quality of whatever you're buying.