Dual CC's one battery

garynappi · March 2020

I currently have two panels (100w + 125W) connected to a morningstar Sunlight 20 (with circuit breakers no diodes) which has worked very well for my home perimeter lighting system and water feature pumps. It has no inverter and is not grid tied.

The current CC has multiple fixed on/off settings for the load and as I have it set (dusk to dawn) the load comes on when there is still a substantial amount of light in the evening and stays on well into the dawn hours. I would like more programmability in the load feature as well as I would like the new CC to provide more system information regarding In/out current / charge state, etc.

So I want to split the system temporarily with two different brand PWM CC's connected to my single 100Ah battery in order to test the on/off load programmability of the new PWM controller. Are there any precautions / hardware or install procedures I should take to avoid system failures or can I simply connect the output of the two CC's to my single battery without any additional hardware?

Thanks for any advice.

BB. · March 2020

My suggestion is to "home run" the connection from the Vbatt terminal on each controller to the single battery bank. This way, each controller "sees" the proper battery bank voltage and you have less interference between the two controllers (i.e., if daisy chain connection, the two controllers will see the voltage drop from their charging current and could confuse each other).

And, ideally, each controller should have its own fuse/breaker when connected to the battery bank to protect its wiring from short circuits.

Two controllers (and solar arrays) in parallel to the same battery bank will work fine. Whichever controller has the "higher setpoint" will "win".

-Bill

Dual CC's one battery

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