Will this system work?

[rcflyers]

I would like to fit a solar hot water system on my roof above an existing Velux window as this means I can easily fit it and maintain it myself.
My existing hot water tank cylinder an indirect coild in it which is heated by my system boiler.
The cylinder is in the airing cupboard on a stand and the top of the cylinder is 1.6 metres from first floor level.
I can remove the existing immersion heater from the top of the cylinder (never used it) and fit a coil in it's place that will have the hot solar water circulating through it.
However, to get the pipes from the proposed panel site to the cylinder means running them under the floorboards and it is a run of approximately 7 metres horizontally.
I can mount the bottom of the solar panel about 1.8 metres above first floor level.
I was hoping to put a tank and pump in the airing cupboard on the floor.
My question is:
Do you think that the water would drain back when the pump stops bearing in mind the minimal head between the bottom of the panel and the coil in the cylinder and the 7 metres or so of pipe run to connect the 2 together?
Thanks for any replies.

[inetdog]

Are you talking about reverse siphon flow cooling the tank water when the panel is cold or actual drainback as with air filling the panel in an open system?