105v trigger.

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hello. i have 4 solar panels series producing 120volt dc.i want a schematic with they go under 105v to start a power supply.

is there an easy way to do this?

 

[JonSnell Electronic]

If you use a contactor rated at 24volts DC and a 1N5377BG Zener diode, when the voltage reaches approximately 15Volts plus the diode breakdown voltage (in this case 91v), the contactor will drop out connecting and the contacts will change for a power supply instead of the solar panels.

 

[back]

If you use a contactor rated at 24volts DC and a 1N5377BG Zener diode, when the voltage reaches approximately 15Volts plus the diode breakdown voltage (in this case 91v), the contactor will drop out connecting and the contacts will change for a power supply instead of the solar panels.

thanks a lot great info.

 

[Osvaldo de Banfield]

I also have solar cells, but at 12V instead of 110V. The black box at the wall is a switching regulator designed of my own.

 

[back]

mine are series connected or it would be easier.

 

[Osvaldo de Banfield]

I have them wired in parallel. Almost all my radio station is sun powered. Also I have emergency lightning with the 12V system.

 

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it have 4x250watt.they were parallel until now and was producing 5kwh/day,almost all my house.but now i want to add two more because the winter is coming and the current would be huge so i changed to series connection.

p.s.i tried a 30v relay with 91v zener and it seems to work.i will do more testing tomorrow.

 

[Osvaldo de Banfield]

I'm generating only 90Wpk by the moment :-D

 

[dangus]

Won't the panel voltage rise once the load is disconnected, causing the relay to behave like a buzzer? Maybe it's better to just isolate the panels with a rectifier. You can spare a diode drop, and DC will be prone to arcing if you don't use the right kind of contactor or some kind of semiconductor switch.

 

[Osvaldo de Banfield]

Yes. To avoid this effect in my regulator, I used a window comparator: starts charging at 20V and stops at 14V at the regulator's input.

 

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it didn't work.when the inverter disconnected the full voltage passed through the relay and the zener and the soldering melt.
i guess i need a comparator.

 

[Osvaldo de Banfield]

Remember that solar cells are current sources, not voltage. then it's output impedance is high.

The equivalent model is escentially a current source in // to a diode join.