Installing a solar panel to charge battery

[geoff5093]

I'm not sure if this is the right place, so if it's not feel free to move it. I have an APRS digi set up on top of the hill running off two deep cycle marine batteries, I would like to setup a crossband repeater there as well if I can find a way to keep the batteries charged.

Anyways, I'm trying to figure out what size solar panel I would need. The HT I'm using is a VX-6R which consumes 1.6A when it transmits at 5W and 150mA when receiving, which is on average once every 1-3 minutes, and a TinyTrak4. I was told that a 15W solar panel such as this would work well in addition to a charge controller (12v Solar Battery Charger 15W). The two batteries when fully charged tend to last 3-4 weeks before getting to the 12V mark.

Now if I add the crossband radio which consumes 13A at 50W and 1.2A when receiving, which would be used maybe 15-45 minutes per day, I'm curious to find out how large of a solar panel I would need. I know it depends on how much sun I get at the location, but assume that I get sun most of the day.

Thanks!

[Thayne]

Out there on the net there are quite a few worksheets to figure that out very closely. I did it for a repeater for a friend of mine, and he didn't believe the calculations so he ended up adding another panel. Those calculations even take into account the weather, seasonal changes, Lat-Long , etc.

Check on solar panel vendors websites.

[geoff5093]

I'll check them out, thanks!

[N_Jay]

Do the math.
There are plenty of good references on line.

W-Hr in needs to be 1.2 to 1.5 times W-Hr out.