I'm Glen the founder of Veggie Patch Ideas. I have been gardening all my life, with a passion for growing perfect vegetables. I Run an allotment site of 80 plots and I'm the host of Veggie Patch Ideas YouTube Channel.
I'm using a 20w panel as my usage will be low (I'm only using 12v Plus USB sockets.) so its only needed to trickle charge the battery. for more power hungry environments increase the size, but remember to increase the size of charge controller as well.