First of I would like to introduce myself and show my appreciation for such a compilation of experts in the solar field.
I'm a current returning Army Warrant in the Electronics MOS arena and building a home in SW Florida. It is my plan to offset the utility bill by installing Solar PV panels and Solar Hot Water & Pool heating. As most, I am trying to calculate the cost vs benefits vs ROI. I want to do most of the work myself, as I feel I am some what qualified. My first dilemma is this:
The Pool Pump:
The plan is to have a small pool (10,000-12,000 gallons) with a roof top solar collector for pool heating with a small 4 person spa. I calculated approx 30 gallons per hour needed to turn the pool over once in a 6-7 hour day. I was going to use a Haywood EcoPump with a about 1KW of solar panels fed through either 4 Enphase MC215 inverters or a 1.5 KW grid-tie inverter. Based on my research and calculations..the pool pump for most of the day would only draw approx 200-300 Wh...so theoretically during that time, I would be offsetting my A/c and other electrical uses in the home with about 600-700 Wh of energy (using 90% eff as a basis). Not sure what a new Carrier 21 Seer A/C unit uses in low speed and high speed compressor mode, but 600-700 watts..is still offsetting). Total for the solar and inverters should be about $2,000, not including installation.
Sunray has a solar pool pump system that they say is more efficient than using a VFD AC drive. Theirs is a Lorentz dc pump (PS600) connected directly to the PV panels through a MPPT controller. This would save $$ on JUST the pool pump energy, but provide no offset to the house during lower pump needs. Their philosophy is pump at max available speed based of PV panel ... pump all day..more water turnover..better. However, I belive I can achieve the same running the Haywood at 30 GPM speed (1400 RPM or so) AND provide excess energy back to home to offset other loads..mainly HVAC.
Lastly, the SunRay system would cost almost double vs the 1KW panels and inverters. I think the Haywood with the 1KW panel setup and inverters is a smarter way to go, less cost and would reduce total overall home energy cost.
Is my thoughts and math correct...Am I on the right track...or am I missing something?
Thanks for any assistance,