I noticed you are looking for a professional and clean wordmark, so here is the idea I came up with... #20
The "E" is a plug that would go into an outlet, the "O" has a lightning bolt thru it and the "S" is a dollar sign $. I wasn't 100% positive if you used a $ as a monetary symbol or not, but I figured I would include it.
Let me know what you think, and we can from there. Thanks!
And here are a couple other options, so you can see how it might look if you used their dark green as the background. Personally, I really like how the orange and white pop off of the dark green.