waynefromnscanada wrote: »
My first thought was that he wanted to use them (or one) as a voltage regulator/charge controller. There are a number of problems with that idea, the most pressing being that zeener diodes, as Cariboocoot mentioned, have extremely low current handling ability before they overheat, short out and vaporize in a puff of smoke.
Connect them to your solar panels only if you want to see what happens when they fail.
Urbandialect wrote: »
I was thinking i could use a zener as my charge controller, yall know how cheap i am, but the more i researched it the more i realized it was a dumb ideal
niel wrote: »
... more parts are added to make up a more elaborate regulator circuit
zener can't make a good battery charger,
Cariboocoot wrote: »
Except that solar panels are current sources, not Voltage sources.
A little bit of light hits them and the Voc goes right up. A Voltage regulator is going to try and regulate Voc, which applies a load to the terminals causing the Voc to drop like a rock until enough light falls on the panel that it can produce some current. Meanwhile the regulating circuit has switched off again and the Voc has shot up again and the regulator tries to clamp it down again and ... eventually the panel will manage something along the lines of Vmp * Imp. But as far as the panel is concerned, maintaining Imp is what's important. Put more load on (i.e. try to sink excess Voltage) and it will allow V to drop so long as it can maintain I. You could end up with a panel producing full I at some small portion of V and a regulator going nuts trying to manage this into a fix V*I output within the right range.
In short, this makes it a bloody awful power source. Perfect for charging batteries though, since you want max I at the low V point of the discharged battery and then have it taper off as V increases.
A simple circuit isn't going to do it without risk to the device being powered. The closer the panel's spec are to the loads, the easier it will be. You're after <8 Watts of power from a 24 Watt panel. In overly simplistic terms that means 16 Watts has to go somewhere. Try for something like the PWM used in simple charge controllers substituting a capacitor for the battery part. Just enough cap to smooth things out and keep the thing running and just enough pulsing to keep the cap charged. When the panel is disconnected it produces nothing, so there's no "excess" power that needs to be shunted anywhere.
Thirty years ago I would have known what I was talking about here. That's no longer the case, I'm sorry to say.