A steep summer electricity bill led one Massachusetts resident to try a lower-cost solar option, and he said the system is reducing his payments. Rather than signing up for a roughly $30,000 rooftop installation, CBS Boston detailed how he spent about $1,500 on a plug-in array in his backyard. What's happening? After receiving a $1,200 electric bill, Andre, a resident of Fitchburg, decided to pursue plug-in solar, according to the station. "I wa…