Solar Panel Blocking Diode

[TSB240]

My scotish heritage persuaded me to go bin diving and rescue a solar panel from the Skip....

It is a Solarex 5w wafer thin metal backed panel

I found that the reason for disposal was the wire connections to the ribbon strips had corroded away.

After a liitle while I managed to solder a new cable in place and was very happy to see it was topping up my old bangers battery at 0.5 amp in the midday sun.

However the blocking diode is beyond being rescued and all ID has been washed off.

Can anybody be kind enough to recommend a suitable one and or an RS reference number?

Steve

 

[VicS]

My scotish heritage persuaded me to go bin diving and rescue a solar panel from the Skip....

It is a Solarex 5w wafer thin metal backed panel

I found that the reason for disposal was the wire connections to the ribbon strips had corroded away.

After a liitle while I managed to solder a new cable in place and was very happy to see it was topping up my old bangers battery at 0.5 amp in the midday sun.

However the blocking diode is beyond being rescued and all ID has been washed off.

Can anybody be kind enough to recommend a suitable one and or an RS reference number?

Steve

Any of the small 1N series silicon rectifier diodes 1N4001 be be adeqaute. (1amp 50v PIV)

A similar rated Schottky diode will have a lower volts drop

There was a lengthy debate on here recently about whether or not a diode is necessary. There seemed to be a powerful argument along the lines that what is lost in volts drop is more than saved in preventing reverse flow at night.

 

[charles_reed]

Any of the small 1N series silicon rectifier diodes 1N4001 be be adeqaute. (1amp 50v PIV)

A similar rated Schottky diode will have a lower volts drop

There was a lengthy debate on here recently about whether or not a diode is necessary. There seemed to be a powerful argument along the lines that what is lost in volts drop is more than saved in preventing reverse flow at night.

or the other way around!!!

 

[VicS]

or the other way around!!!

Yes, sorry, the other way round

 

[tawhiri]

Zero voltage drop diode

Yes, sorry, the other way round

There is a so called zero voltage drop diode. it is infact a MOSFET, see below:
http://jeelabs.org/2012/05/30/zero-voltage-diode/

 

[Rigger Mortice]

There is a so called zero voltage drop diode. it is infact a MOSFET, see below:
http://jeelabs.org/2012/05/30/zero-voltage-diode/

You can't use a MOSFET in the same way as an ordinary diode or a Schotky diode. It needs circuitry to switch it on and off....... Which begs the question as to whether or not that would be a more efficient way of doing the job. I don't know the answer but the circuitry wouldn't be difficult to put together. However, by the time you've done all that it would be just as easy to fit a proper regulator.

 

[halcyon]

You can't use a MOSFET in the same way as an ordinary diode or a Schotky diode. It needs circuitry to switch it on and off....... Which begs the question as to whether or not that would be a more efficient way of doing the job. I don't know the answer but the circuitry wouldn't be difficult to put together. However, by the time you've done all that it would be just as easy to fit a proper regulator.

They also have a body diode that conducts in reverse, this is not shown in the diagram.

Brian

 

[charles_reed]

You can't use a MOSFET in the same way as an ordinary diode or a Schotky diode. It needs circuitry to switch it on and off....... Which begs the question as to whether or not that would be a more efficient way of doing the job. I don't know the answer but the circuitry wouldn't be difficult to put together. However, by the time you've done all that it would be just as easy to fit a proper regulator.

I have to agree - when I found that for the last 10 years Kyocera hadn't been fitting blocking diodes diodes to their panels - I fitted an MPPT controller with a nominal 24v input but having a blocking diode.
Now I have to say that whilst I'm unconvinced by the claims for greater output via an MPPT controller it certainly ensures that input volts are always higher than system volts and that the blocking diode ensures no reverse discharge.