12v Battery - do it myself?

[MrFixit]

May be out of the country for a month, and the car will be outside. Anybody used a solar battery tender on the Clarity?
e.g.,

No direct experience, but it seems like a great idea and I can't think of a reason why it wouldn't work.
It is not nearly as sophisticated as a real 'battery tender' with all the correct hooks to monitor the charge level, but it is only 1.5W (125 mA) so it' not going to hurt anything and it seems like this ought to be enough to mitigate the small parasitic loss.

 

[Landshark]

May be out of the country for a month, and the car will be outside. Anybody used a solar battery tender on the Clarity?
e.g.,
https://www.harborfreight.com/15-watt-solar-battery-maintainer-64251.html

I used a 1.5w panel on a riding lawn mower for years, clipped directly to the battery terminals. For the truck, boat and boat lift I use 10w panels. If you’re connecting it through a cigarette lighter outlet, make sure it isn’t a switched outlet. The truck has 3 outlets and only one is hot with the ignition off.