Need help with Solar water heating,Collectors

 Hello I live near Canada where we get -30 during winter. I have A indirect hot water heater,in conjunction with home hot water boiler.
Would like to go solar for my DHW and store extra for home use. My delema is, with so many solar collectors out there what are the best from experience. I would like in-put on the 12 v. p/v systems as they sound the most simple system to run.
I will be running a glycol system. What heat exchanger perform the best? And what 12 volt pmps seem to run the best.
I am using a bell and gosset + taco pumps for my existing system now.
My home is around 2500 sq. ft. any idea as to what might be needed for collectors to hedge in winter with solar.
 Thanks all,Chuck