I don't bring a $200 solar panel camping with me because I think it will save on my monthly electricity bill compared to getting those joules from the household

I don't bring a $200 solar panel camping with me because I think it will save on my monthly electricity bill compared to getting those joules from the household outlet. I bring it with me because the household outlet is not available at my camp site. Similarly, in this case, I think "saving $50/year" is the wrong comparison. Its value comes from adding charge to the battery in locations where you probably don't have the option to pay the meter price.