I live in northern PA and I have over 600 gals of storage for my wood boiler. I have started thinking about adding a homemade solar panel to heat the 600 gal which in-turn will heat my DHW. So far I have looked at many solar collector options using PEX, CPVC, and copper that are encased in a simple insulated box with glazing on top. To heat the water inside I plan on putting a coil in a 30 gal propane tank with a PEX or copper coil in it. All this with a small pump to keep the water flowing. The tank will be plumbed in series with my 600gals so I will rely on stratification to get the heat where it needs to be in the tanks. I am hoping this will reduce/eliminate the need for me to fire my boiler much in the summer. Does anyone have any suggestions as far as materials, designs, or experience with such systems?