Solar panel diode question

[5teve]

Hi Guys

Quick question about a small solar panel i have (10w)

I know i can hook it up to an n70 direct except using a blocking diode to stop discharge at night. however it will be left on the boat maintaining the aux battery all the while... without a regulator am i likely to boil it?

Inside the junction box there is already a diode across the + and - terminals (there are only 2 terminals on this panel)... and for the life of me i can work out why! Any ideas?

My thoughts are to take the diode out and use it as a blocking diode instead.. i know they cost nothing to buy... but its just reusing what is there.

So by removing and changing the config of that diode am i introducing any issues?

Thanks in advance

Steve

[JDNSW]

1. I think that the diode across the panel may be to allow current to flow through the panel if wired in series with another, if it is in shadow or the other is providing more current. However, it also provides spike protection. I would leave it there and fit an extra one.

2. A 10W panel will only produce a maximum of about 500mA. I know you might think that it should be a bit more, but believe me, it won't be! (Reason is that the rated power of a panel is at about 18v, which you will never reach connected to a battery)

This current will not boil an N70, although over a year or so it may need topping up.

John

[bee utey]

1. I think that the diode across the panel may be to allow current to flow through the panel if wired in series with another, if it is in shadow or the other is providing more current. However, it also provides spike protection. I would leave it there and fit an extra one.

2. A 10W panel will only produce a maximum of about 500mA. I know you might think that it should be a bit more, but believe me, it won't be! (Reason is that the rated power of a panel is at about 18v, which you will never reach connected to a battery)

This current will not boil an N70, although over a year or so it may need topping up.


John

Spot on. As you aren't fitting the panel in a series string you don't need the diode there but its doing no harm. however a cheap regulator will reduce water loss in full sun.:)