Check extensive information on tech and satellite phones at the Human Edge Tech site. Click here.
Solar panels work great on Everest. Just lay them out and hook up to a simple car battery and you will have more than enough power. We used 3 panels and filled our 210-amp battery in one day. Shop around at marine suppliers.
You should buy the battery in Kathmandu and fill it in BC. If daily power is very important to you, bring a generator. Pick it up for a few hundred dollars in Kathmandu.
Your trekking agency will help you find fuel.
Connect your battery to an AC/DC converter (US 50 and up at your local electrical supplier or hardware store). Now you can plug in your TV and watch MTV India.
No, really, you are in a national park. Use your generator only when absolutely necessary.
More info on power and solar panels at the Human Edge Tech site.
There are a number of brands around and new smaller units are constantly hitting the market. Choose a model with AA-batteries since charging high up is a problem. Lithium batteries are expensive but outstanding with respect to weight factor and cold tolerance. A Lithium battery will perform with almost no loss down to -20C/-30F.
Every climber and summit sherpa should have his/her own set. There should also be a unit at C2 and of course in BC. Check the second hand market and/or last year's expeditions for good deals.
Using a base station will enhance your possibilities to communicate when it's really important - in bad weather.