Snubber Circuit for Serial/Parallel Solar Relay

Thread Starter

Mustang1965

Joined Feb 20, 2013
17
I did look at a some of the threads here regarding the Snubber circuit, and did not come across one that I thought would meet my needs. Ok, before you tell me that I will not see any significant difference in automatically switching my 2 SOLAR panels (30 volt) between a SERIES circuit or a PARALLEL circuit automatically, I need to prove it to my self. It is just the way I am. So, I am including an attachment with the circuit. The relay I am struggling to locate is a "Break before Make" that will handle 10 Amps. I am looking at inserting a 30 amp Wind Turbine blocking diode, just in case there is a relay malfunction. What I am looking at is when the circuit is triggered to go from SERIES to parallel as the 20 amps will probably cause an arc between the relay contacts and the SOLAR charge controller (Morningstar MPPT TS- 60). I have a few of the blocking diodes from a previous project, so now I need to suppress the 20 amps when they switch from SERIES. I do not believe that the 60 volts (9 amps) will have an affect on the circuit as much as the PARALLEL design. Any thoughts and parts... Originally, was thinking of an MOV.
Automating the switching will be done with either an Arduino or Raspberry Pi2, and measuring the current that is being generated by the panel(s), Will add a shunt to each of the panels to better make the decision as to PARALLEL or SERIES. Along with a photo cell in a frosted cup to measure the intensity of the sun/clouds...

Thanks in advance for any assistance,
Don
IMG_1097.JPG
 
Last edited:

BR-549

Joined Sep 22, 2013
4,938
"Ok, before you tell me that I will not see any significant difference in automatically switching my 2 SOLAR panels (30 volt) between a SERIES circuit or a PARALLEL circuit automatically, I need to prove it to my self."

How do you define difference?
 

Thread Starter

Mustang1965

Joined Feb 20, 2013
17
"Ok, before you tell me that I will not see any significant difference in automatically switching my 2 SOLAR panels (30 volt) between a SERIES circuit or a PARALLEL circuit automatically, I need to prove it to my self."

How do you define difference?
Panel output current.

Should shading, dirt, clouds... cover one panel while wired in SERIES mode opposed to being wired in PARALLEL. Voltage should stay about the same...
 

nsaspook

Joined Aug 27, 2009
7,985
Panel output current.

Should shading, dirt, clouds... cover one panel while wired in SERIES mode opposed to being wired in PARALLEL. Voltage should stay about the same...
What is the required controller input voltage? What is the panel voltage. You don't want to switch live panels like that normally. If you have two panels strings make each string match the required CC input voltage.
 

Thread Starter

Mustang1965

Joined Feb 20, 2013
17
nasapook, I have 2 panels at the moment. The max allowed input voltage from the panels to the charge controller is 150 volts, and 800 watts on a 12 volt battery setup. In series they will be pushing 60 volts (10Amps) in parallel 30 volts (20 Amps. I am looking at automating the system based on current/TOD/shade, because one of the panels does get partial shade.

Thanks
Don
 

nsaspook

Joined Aug 27, 2009
7,985
nasapook, I have 2 panels at the moment. The max allowed input voltage from the panels to the charge controller is 150 volts, and 800 watts on a 12 volt battery setup. In series they will be pushing 60 volts (10Amps) in parallel 30 volts (20 Amps. I am looking at automating the system based on current/TOD/shade, because one of the panels does get partial shade.

Thanks
Don
What is your realistic expectation of power gains from this switching network?
 

Thread Starter

Mustang1965

Joined Feb 20, 2013
17
Realistically, I have no idea as to what the power gains would be by automating the series/parallel configuration... I have always been curious as to what the answer would be and that is what has given me the incentive to try it in a project. The design portion was easy, it is the selecting the proper parts for the snubber circuit, that is the issue. I am thinking about putting a 1K to 2K micro Far.. capacitor across the contacts, to see if that would eliminate or reduce the arching...

Moving a panel is not an option...

Don
 
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