Best way to add 3-4kw of panels to current system

[RKG76]

Hi...looking for a little advice...I have an older system that still works well (48v Magnum inverter/charger, Midnight 150 CC, and one 48v powerpro EG4 battery, 1800 watts of PV with 9 200 watt panels (Canadian Solar panels about 10 years old) 3p3s configuration into and combiner box)

I just would like to add 3000-4000 watts of panels and wondering the best most affordable way to do this? Not sure if I just need to add a separate CC and that is it or if there is more to it.

Thanks in advance for any suggestions!

Russ

 

[MichaelK]

If you look at the Midnight manual in detail, you'll see that your 150V model can handle up to 83 Amps of charging current. Assuming your battery starts charging at 50V, and you want to de-rate the panels to 90% to account for real-world losses, then what you can install (83A X 50V)/90% = 4611W of panels. So, you could immediately double what you already have installed with no concerns at all.

You could install up to an additional 2800W of panels and still stay within your 83A limit.

If you wanted to surpass that, an additional option is to employ virtual tracking. That is have additional panels facing other directions instead of South. Right now today, I have 4500W of panels facing due South for my Midnight200, but have an additional 3000W facing due West. By the time the sun if far enough West that the Western array starts making a substantial amount of power, my South-facing array is dropping off. That keeps the amps flowing, but doesn't exceed my amp limit.

BTW, there are likely to be more economical panel choices out there instead of the 200W CS. Shop on Craigslist with local cash and carry pickup for the best deals. Expect to get between 3-5W/$ with local pickup. I would though bring a voltmeter with you to measure each panel you buy. Don't pay for anything with a Voc >10% less than the Voc documented on the back of the panels.

Once you find panels, your only concern would be that the voltages of the new panel strings match your original 3S strings to ~5%.