perhaps you are not getting a good connection, maybe but dont hold me to this but maybe put vassoline or something like that on the male part of the bulb to get a better connection?
I would have to recomend all of the above but with a few solar panels, why waste sunshine? you could have them power your house and if you make more than you use it can go right into the local power grid, and run your meter backwards potentaly giving you a check from the power company instead...