For $28 dollars I'm curious as to what the specs are for these cameras? Like sensor size, horizontal lines, minimum lux, etc? Are you using them for CCTV recording, or just to see 'who's there'.
Also, what voltage does the panel put out, because you'll need 13-14V to actually charge the battery.
EDIT: I've found the 2.4GHz area to be very cluttered with various 'nanny cams' and such. When we cruise our boat down to Oriental, across the port there is a little shrimp operation. The have like 8 cams in the 2.4GHz range. I always bring my receiver and plug it onto my TV so I can snoop in on them!