A Crummy Commercial

I took a second look at measuring the leakage current of the Renogy solar panel - that first reading of ZERO current kinda bugged me. https://wb9kzy.blogspot.com/2026/05/the-renogy-solar-panel-dischargeleakage.html   I used the newer Triplett DVM just in case there was some kind of problem with the Metex used before.   At 12.84 volts I again measured zero current in any of the three ranges. So I was thinking about that and this is my surmise: there are lower voltage Schottky diodes like the 1n5818, 1 A diode I used on the other solar panel.  The low voltage diodes have somewhat high leakage currents.  Then there are higher voltage Schottky diodes for use in switching supplies and the like.  They have higher forward voltages but smaller leakage currents.  Here is part of a Nexperia Schottky diode data sheet: I will have to pay the tariff tax and get some of these How does this fit in with the Renogy solar panel ?  The Renogy has 72 solar cells which I a...

Renogy made this 10 watt solar panel bought this year: https://wb9kzy.blogspot.com/2026/03/solar.html so as was mentioned yesterday: https://wb9kzy.blogspot.com/2026/05/32-diodes.html lets look at the leakage current involved.  As with the UPG solar panel from yesterday, I waited until dark, then covered the panel and measured the battery voltage and the battery to solar panel leakage (discharge) current: 12.84 volts but ZERO current, there must be some kind of low leakage circuit inside the Renogy panel ? I didn't bother to count the lines (diodes) on the Renogy, counting gets tedious after a while and also this panel seems to be different.  But the specs are almost identical: The problem with having the nice cables and clips is that I hate to cut them to add a diode but since there is no leakage, no cutting required, nice ! Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm

I was thinking about the series blocking diode addition to my recent solar panel purchase: https://wb9kzy.blogspot.com/2026/04/make-or-buy.html Certainly there is a drop across the diode when the panel is charging, less than 250 mV with low current.  But is it really needed ? Looking at the solar panel itself again there are 6 wafers, each wafer has 6 groupings of photodiodes with 6-5-5-5-6 diodes each or 32 total diodes in series. count the wider horizontal dark lines to determine the number of solar cells   Per Wikipedia the output voltage of a silicon solar cell (diode) is .5 to .6 volts.  Multiply 32 diodes times .56 volts gets to roughly 18 volts which is about the rated voltage: 21.6 volts divided by 32 is .675 volts so this sounds reasonable for a no-load situation. Now since the panel is charging a lead acid AGM / gel-cell battery the highest voltage that the battery could apply to those 32 diodes is roughly 13 volts: source:  https://voltagebasics.com/lead-a...

I bought another solar panel since this one: https://wb9kzy.blogspot.com/2026/03/solar.html This second one has similar specs and cost about the same but it was just a panel.  It didn't come with all the little cables and clips. I like solar panel specs, right on the back, easy to test, nice ! One thing I added was a series diode to prevent the battery discharging through the diodes of the solar panel at night.  I might change out that diode later for a MOSFET circuit but I'll have to research that to see what the pitfalls might be.  One problem is that the solar panel puts out 18 volts or more in full sun and that much voltage would probably zap the gate of a MOSFET.  So a circuit is required to protect the gate.  Another thing is that as I've encountered before, MOSFETs can conduct in both directions (unlike a diode).  So maybe it's best to just live with the voltage drop across the diode for now. The other thing I'll need is a cable which can easily be c...

I saw this blog post on EDN about a Renogy 10 watt solar battery charger: https://www.edn.com/jumping-the-jeep-an-alternative-cost-effective-solar-cell-example-app/ So I bought one on Ebay, not new but sent USPS in a box, nice.  It arrived today and looks OK although there was a little gunk on the panel surface which wiped off with a little distilled water, no problem. it even came with hookup cables, nice I hooked it up to the lawn tractor battery and saw about 170 mA in the noon sun - not super huge but the rated max short circuit current is only 590 mA  ?  I took it outside and got 500 mA of short circuit current, pretty close to the spec considering sketchy current measurement and the fact that it's still technically winter here. specs are screened on the back covering Note my previous solar battery charger panel from over 30 years ago (bought at a True Value like "the Mangler" pliers - why did I shop there ?  :)   only gives about 30 mA of short circui...

That same joker from the USA has apparently moved to Germany in the 21st century but is still finger writing: source: https://core.ac.uk/reader/237468620 Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm