Tried to post a response earlier, but seems not to have made it through. If it eventually does, my apologies for the double post.
I've been thinking of doing a similiar system. Problem with solar is that effeiciencies are highest with low collector temps, but the heat recovered is diffuse and not as useful for heating. And you still have a lot of heat left over that can't be used for heating. I talked to a geothermal salesman, he advised against high entering temps. I didn't completely understand, but maybe higher temps =higher pressures that are hard on the compressor. He suggested dumping the heat in the ground loops, but I think that is very inefficient. If you find a heat pump that works with higher temps, please post, I'd be interested in using it.

The only thing I could come up with, is to have two water storage tanks, one lower volume that is hot for heating, and another with greater volume that can cool wasted lower temp H20 in hot tank to temp for heat pump. Cool by mixing tank tanks, or using heat exchanger. Heat pump loop goes through cooler tank.
I was thinking larger tank could be used to collect and store rainwater in winter for use in the summer. As heat demand increases in fall and winter, larger tank is being replenished by rain. Dual use for the extra tank makes it more econonical. WIth say 70 F water, your COP would still be much beter than 50-55 F geothermal source.

Hydron has specs for EWT of 90°. You get COP's around 5.5. In theory, you could heat the water from 90° to 120° maybe 125.° I haven't tried this so I can't speak from experience, but it sounds like it should work.

What really is the purpose of doing this? What is it you'd want to heat with that 150,000 BTUhs? To heat a hot tub? a pool?

"When my 400 gals of water in my solar hot water tanks drops to around 95 degrees, the btu's left are useless"

Could you elborate on this? I don't quite understand why.

I run my in floor radiant heat at 99 degrees. I would run it lower but that is the lowest that the heater goes to. I would think that you could continue to use water at a temp as low as 80 degrees and still get a benefit.

Depends on the type of radiant floor installation you have.  For staple up with or without plates, a temp of over 100F is usually necessary.  For concrete slab or Warmboard (or similar), much lower temps are appropriate.

These numbers I'm using are trying to make the point that I said in the past, it's very unlikely to heat your home with solar hot water panels.

Let the numbers do the talking. Take 400 gals of water x 15 degrees (95-80) x 8.33= 50,000 btu's. Yes you do get benifit but when you figure in the cost of electricity and the meager 50K potential gain it doesn't add up to heating your house that much. This will also leave you with nothing for DHW. One other thing I learned with my solar experince, reality is usaully not as good as the numbers because of a bunch of hidden losses.