Going green

Going solar – when should I jump, and how many panels?

Pondering adding to the solar hot water on my roof with PV panels for electricity generation. My last electricity bill says I used up 659 kWh in 92 days, costing $187.61 (only including the cost for power and the 100% GreenPower surcharge; excluding the $76.41 service charge which I'd incur no matter how much power used)... that adds up to 2614 kWh in a year costing $744.32, or about 28.5 cents