There seems to be a lot of talk these days about saving electricity. And rightly so! Electric rates have gone way up, and people are starting to feel it in their checkbooks! I thought this to be appropriate for the "deep-end". (Even though I don't have one ) I have learned so much here at TFP, I thought I would share some of my experiments.
My recently completed AGP is 15x30 (12,000 gal) and I am using a Tagelus TA-60D (300lb) sand filter with a 2-speed Waterway Supreme HI-FLO pump 3/4 HP. Also installed are 2 Fafco "Solar Bear" panels each 4x20 plumbed using PVC. I can switch the solar on and off using a 3 way valve. The 2 panels are currently plumbed in series only because I didn't have all the PVC fittings I needed. I will make the change to parallel flow soon to increase GPM flow.
The pump data-plate specs are:
Model #: PSP2075-6R
Amps: 8.8 (Hi) and 2.6 (low) which calculates to 1012 watts (hi spd) and 299 watts low speed.
Using a Kill-A-Watt meter, I was able to determine that my pump uses significantly less power than its data-plate suggests :P
Hi-speed without solar (less head; higher flow): 745 watts
Hi-speed with solar (more head; lower flow): 662 watts
Low-speed without solar: 138 watts
Low-speed with solar: 127 watts
Let's calculate how much this will cost per month if the pump is run 10 hours per day on low speed with the solar turned on:
Cost per KwH: $0.185
KwH per day: 1.27 (127 watts div 1000 * 10 hours/day)
Days per month: 30
Cost to run pump on low speed per month: $7.05
Initial flow rate measurements seem to indicate I am only getting about 15 GPM. Hopefully this will increase when I switch the solar to parallel flow. But even this seems sufficient to keep my pool clean and warm.
Of course this does not take into consideration electric-motor startup surge, or running the pump on high-speed for cleaning or back washing, but I expect this to be a rather small cost.
I attached the pumps head/flow graph.
So the whole point of this is you can save significant money by running a 2 speed pump. I still need to do more precise flow rate measurements. Hopefully I can have those for the forum soon.