Pump Recommendation - 2 Speed or VFD for new Solar System

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english72

0
Nov 14, 2011
18
Galt, CA
I'm looking to add solar to my current pool setup. I'm currently shopping for solar panels and have currently measured my roof surface. I could install (6) 4x10 and (6) 4x8 solar panels which would equate to about 75% of my pool surface and not require a solar pool cover. I'm currently looking at the Aquasol Solar Panels, Powerstrip by H2Otsun, or something similar to the Vortex. Based on the information from Aquasol, they recommend 44 GPM for best solar efficiency. Below is my current pool and equipment setup. Currently my electric utility is offering a $350 rebate on Variable Frequency Pool Pumps and I have found an Intelliflo for $850 delivered. As an electrical engineer I know a lot about VFD's and how they work along with how they fail. Would it be better to replace the single speed motor on my current pump with a 2-speed motor or replace the pump with the Intelliflo? If I go with a 2-speed setup I would like to run my solar on low speed. My current pump is about 11 years old and has never had any issues since we purchased this house in 2012. My only concern with going with the VFD based pump is I believe that it will not have the same longevity because of the electronics. Also, during this solar install I'm looking at adding automation. Finally, my current pump (Sta-rite Max-E Pro) is rated at 1.5 HP with a SF of 1.47, which I will need a pump at least this size to run my 4' shear water feature. Any recommendations would be greatly appreciated.

Here is my current pool setup:
20,000 Gallon IG Pebble-Tec
(1) 2" Suction to Pump from 2 Drains and 2 Skimmers (shared pipe)
(1) 2" Return to (5) 3/4" eyeball fittings
(1) 2" Return to 4' Shear Waterfall
(1) 1.5" Return to Pressure Side Cleaner (Polaris 360)
Sta-Rite Max-E-Pro 1.5 HP Pump (P6E6F-207L)
Sta-Rite System 3 (300 Sq Ft) Filter
Distance to furthest Skimmer 46'
Distance to furthest Return Eyeball 60'
Using the BBB method

The suction pipe into the pump is 18" above the pool water level. Currently when I'm filtering the pool (no Polaris) the gauge on the Filter reads 14 PSI. When I change the valve to run the Polaris and 5 Returns the gauge reads 18 PSI. When I run the 4' Shear waterfall my gauge reads 18 PSI. My current electric rate ($0.14/kwh).
Thanks again
 
With Solar I'd recommend the Intelliflow VS for sure. This way you can get the flow rate you want without spending extra $$ and adding overpressure to your solar array. Basically, if your low speed setting wont drive the array flow, you will have to run it on it's high speed. With the VS, you can give it just the right amount, minimize your power use, and maximize your Solar performance. You could even trade electric use with heating efficiency. For example, in the summer, you may want to use less power and can afford lower efficiency.
 
English,

Not sure what you had in mind for automation, but you need to be thinking about it now. Whatever VS pump you buy, you need to buy the same brand of automation so that the two can talk with each other.

Thanks for posting,

Jim R.
 
I have a two speed pump with a solar heater. In my setup, the pump runs at high speed while on solar. You probably will not get much if any flow through your solar panels when operating at low speed. The pump simply does not produce enough pressure to do that. I have a three way valve connected to the discharge of the filter. One side of the Tee goes to the solar panels, and the other side goes to the returns. The other side of the solar panels also goes to the returns. The three way valve has its limits set so that when going to the solar panel, most of the water is passed directly to the returns, however a small amount goes through the solar panels. The manufacturer of my solar panels recommended a specific pressure drop across the panels (I believe that it was 2-3 psi) so I adjusted the valve limit so that when in solar mode, the filter discharge pressure increased by that amount.

You can get a replacement two speed motor for your pump for less than $250. In any case I agree with Jimrahbe you probably will need some type of automation. I have the Hayward Aqua Plus unit. Has all of the necessary programming built in.
 
English,

Keep in mind that the EasyTouch was designed to talk with the Intelliflo pump not the SuperFlo pump. It can control the SuperFlo with a clumsy relay system, but it is not a true VS speed control. It is more of a select one of four preset speeds, kind of things.

I've said this many times before, but I can run my Intelliflo at 1,200 RPM, 24/7, for less than $20 a month..

Thanks,

Jim R.
 
I run my Intelliflo at 1100 rpm for solar standby, skimming and making chlorine. It uses 150 watts at 1100 rpm. At 10.25c/kWh it costs less than 12 bucks a month to run the pump 24x7 at 150 watts.
 
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