A really good idea, a couple of questions though:-
1) Do I need a Scrobby for each panel (there be gaps between mine)?
2) Do I need to buy the Scrobby Mini to clean scrobby's panel, and the Scrobby Micro to clean Scrobby Mini's panel etc, down to ther Scrobby nanobot to pick up individual dust grains and carry them off to the edge.

The video shows the cleaner moving over two panels so it looks like it move between all the panels in the scope of its tether, if the ap is not too large. I assume you would need to replace the battery and or the cleaning bits- i.e. brushes and its own solar panel on a fairly regualr basis - yearly to a couple of years at a guess. If it using rainwater I imagine they will need to add something into to the tank to control biofilm growth else the jets etc would eventually become clogged with algae etc.

Cute idea, though I have always asserted that you really should not roof mount solar panels if there is any other option because to clean the damned things requires climbing onto the roof ... though in an arid area like the Central Valley of California or Ajo Arizona, there is not sufficient rainfall to manage supporting the little dude.

Living in drought ridden southern California it would be great but what is this "rain' stuff they talk about?

Not an efficient form, even though it uses rain water (sunny climes, & rain not a common balance). Cable guides can be prone to failure, and affected by wind. I understand it is for domestic use, but better solutions do already exist;
http://www.gizmag.com/ecoppia-e4-ketura-sun/31428/
Think perhaps using thermal expansion during the day to store & compress air, release a lateral rotating brush, with gravity assist to slide down at night, rise up the next day.
Or maybe membrane type skin that reacts to the morning sun similar to flower petals, in doing so they daily wipe the surface as they expand, close up and keep the outer surface clean during the night.

What happens when you have 16 panels? Can one fill the water reservoire if your area hardly ever gets rain? How does its own solar panel need to be installed? That could be rather involved a process.

Solar panel cleaning is already a thriving and lucrative service industry. The customer base is now large and the benefits of regular servicing are easy to demonstrate. Business setup costs are small and this type of machine is a game-changer if it can be developed further.

Can this be used for long series of panels or how much area can one scrobby service.How often we may have to service scrubby? How do we contact the manufacturer?

A soft broom and a hose every few months, big deal. I also used to clean mine when I changed them between my winter angle and my summer angle, when I lived on the Tropic of Capricorn.
Aruvqan I mounted mine on the roof of the verandah for the shade value, it hits 45 degrees there.

I have some solar panels on my home, but recently I was told that they need to be cleaned to be at their most efficient. I was not aware of this, so I really need to start working on this. I would really like to have a robot like this that can get them cleaned quickly and clans as often as I need. However, I am not sure if I can get one of those for myself, so it might be better to just find a cleaning service that can come and do it for me. Maybe in the future I can look into an automatic washing robot like this!