Switching from SSE Gas & Electric with Solar Panels + Pre-Pay meters

Sam.W_3

I've been with SSE since I moved here in 2011, I pay money into the Gas & Electric meters once a fortnight and have a lot saved up in there because I have a low income and am afraid of being without either during the winter months, I also have 5 solar panels on the roof which save me electric during the day and especially during the summer months.

I don't know what would happen to the money in the meters if I switch both supplier and to direct debit, I don't want to pay a fortune to change to Direct Debit and I'm just afraid of switching in case it all goes horribly wrong. I've been on the fence undecided for 2 years now.

I can't figure out who would be best for me to switch to in any case because I also want to get rid of the meters. Do SSE even change them for free? Will it start a new contract I can't get out of for 12 months or more?