We have a portable electric penthouse lift assist for sale which was developed and assembled by Sportsmobile West. (I think John Kalmbach had a lot to do with the design.) It is about 46" long and plugs into a 12v cig lighter. To use it, plug it in and center it vertically front/back and side/side:
Push the rocker switch on the control unit and it starts up:
Here it is at the top of the lift:
With the top up, you reverse the motor and run the lift back to the stowed position. It takes about 15 seconds to raise the top with the lift assist. We have 3 of the original solar panels on top of our van which probably weigh about 25 lbs. each and have used the lift a few times when we also have our 55 lbs. kayak on the roof.
The lift cost about $600 new and is for sale for $300 plus shipping. I'd prefer a buyer from the San Francisco Bay area so that we could arrange for a meet/delivery. Otherwise, it will be an interesting challenge to ship it given that it weighs about 11 lbs. and will require a shipping tube about 6" in diameter but I'm sure that I can figure something out.