Both! Hard to say as I've never hooked it up to a proper MPPT to verify, but I suspect my DC-DC is only 80% efficient at best. The panel is '40W' by Chinese standards, so really probably only 35W. I also have a long run of wire through the frame to where it connects to the battery and it's only 18AWG so again, not the best between all those things.donn said:Do you think you're losing a lot in the conversion, or is the panel just not putting out much more than 15W?
That being said, in optimal conditions it can charge around 100Wh+ per day. Considering the battery is only ~700Wh (was 850Wh, but 400 cycles and 5+ years of heavy use has degraded it), and the bike can manage 12Wh/km, that's around 8.3km additional range per day. If the battery were completely flat it could full charge back up from solar in about a week under optimal conditions. I've never tested that though.
Anyway, the point of this thread is the aero...and I gotta say, while I wasn't expecting it, the benefits of the aero this panel gives on this bike when riding are fantastic. It prevents my body acting like a wind sock, it helps keep my hands warmer in winter, and it deflects the rain (which I usually try and avoid) away from my displays and torso.
I have had a few other panels on in the past with a 15W being my first try, then 30W, and now for the last 3 years or so this 40W. If I need to replace this one I might try a 50W which is slightly longer. The challenge then becomes fitting it so that I don't kick it with my feet, and low enough to see over.
I have also considered getting two panels and mounting them into a V shape. Unsure how that kind of setup would fair though...I am not gentle on things!
Cheers