How to keep car battery from going dead when I only drive it at most 10 miles a month?

Update: to not waste fuel and save money I dont leave it running any longer than neccessary. and we barely use it more than 10 miles a month. so every couple months the battery dies and we need to leave it on a charger overnight or get a jumpstart.
Update 2: also how often should I change the oil if it mostly sits around?
Update 3: Could I hook up a small 20W solar panel and suction cup it to one of the windows and run the panel to a solar charge controller and then to the 12v accessory outlet to keep it topped up? our 12v accessory outlet is always on. direct connection via 8awg wire to the fuse block via a 25A fuse
Update 4: car is just started once per month. drive to grocery store. then on our way back home we drop off the bills. thats it really. only about 5 to 10 miles at most round trip.
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