Adding second Solar Controller

[funjohnson]

I currently have a Blue Sky 2512ix mppt charge controller coupled with two Kyocera 135 watt panels (270 watt total). I was offered a great deal on a 205 watt Evergreen 12v panel. All three panels are close enough (.5V of Vmp value) that I thought I could just use my current Blue Sky controller. It wasn't until I paid for the panel, brought it home, and started to think about the amps this third panel will make, that I realized it will not work with my 25 amp controller.

After spending money I wasn't planing on spending, I wanted to just connect a low cost controller to my new Evergreen panel. Unfortunately, I'm not sure if the two controllers will play nice with each other. Here is the question:

If one controller senses voltage from the other, would they think the batteries are charged and go into a float stage? Can you have two separate solar controllers at the same time?

[btrayfors]

Originally Posted by funjohnson

Here is the question:

If one controller senses voltage from the other, would they think the batteries are charged and go into a float stage? Can you have two separate solar controllers at the same time?

Probably they will clash. Your solution might be to get a larger capacity MPPT controller which will handle the amperage of the combined panels. Or, forego the most recent purchase: sell it.

The two 135watt panels with a good MPPT controller should be enough for your boat, unless it's a real power hog. Maybe you can find ways to reduce power consumption?

Northern Arizona Wind and Sun has a good primer on MPPT controllers:
Maximum Power Point Tracking Charge Controller

Bill

[funjohnson]

Originally Posted by btrayfors

Probably they will clash. Your solution might be to get a larger capacity MPPT controller which will handle the amperage of the combined panels. Or, forego the most recent purchase: sell it.

The two 135watt panels with a good MPPT controller should be enough for your boat, unless it's a real power hog. Maybe you can find ways to reduce power consumption?

Northern Arizona Wind and Sun has a good primer on MPPT controllers:
Maximum Power Point Tracking Charge Controller

Bill

We are going to the Bahamas this year and just added a watermaker (katadyn 40e). The watermaker, refrigeration, radar, tv and computer all bring our daily requirements to over what the 270 watts could handle. The 135 watt panels are going on the bimini and the 205 is going on the davits.

[RXBOT]

Can you if you would want to create another seperate battery bank fed by the new panel and another controller. That would add some redundancy say if the present controller failed.

[scottyt]

i second the second bank. figure out the loads and hook up what ever you get out of the second panel and bank. ie if you get 50 amps a day out of the panel and your water maker uses 50 amps hook it direct ( ie normal safety stuff like fuses ). if you do this right you dont even need a big battery, as you are more like using the power as its made, with no real storage needed.

[Stu Jackson]

Why not call the controller manufacturer(s)?

[funjohnson]

Originally Posted by Stu Jackson

Why not call the controller manufacturer(s)?

Funny... I never thought of that simple solution. See, you guys have always been able to answer my questions... I forget about the manufactures.

[funjohnson]

Follow-up

I called Blue Sky and was convinced that I needed a larger single controller instead of the two controller option. I ended up buying a Blue Sky SB3024il and will just sell my old 2512ix on eBay. Now I just need to figure out how to fill the void left by the 2512ix in my beautiful teak nav station!