Here's some data to help you: http://www.welserver.com/perl/plot/...lPower.png

At 6:15 AM it's a 2.2 HP pump motor at about 1900 watts.  A few minutes later it changes to low speed, making it a 0.28 HP pump motor running at about 325 watts.

At 8 AM the motor returns to high speed (to run the spa), again at 1900 watts.  At 8:15 AM the motor changes to low speed, again at 325 watts.

At 12:15 PM a 3/4 HP pump starts up (cleaner), running in addition to the filter pump in low speed.  Total watts is 1600.

At 2:30 PM the only pump running is a 2.5 HP pump, at about 2100 watts.

Best regards,

Bill

I use the "automatic transfer switch" for other things, but as long as your solar inverter shuts down cleanly when it can't drive the output, then it should work fine (it's smart, without any manual action).

Most any DPDT 120V/240V AC relay can be wired up to do this. Two input plugs, one output plug. If plug A has power, it will turn on the relay and route plug A to the output plug. If not, the the relay will drop and plug B will be connected to the output.

In general, I'm going to guess that the power draw of a filter pump is based largely on how much resistance the filter has to flow. So large filters should be able to get the same GPM with a smaller pump.

Posted By jonr on 27 Jul 2012 09:07 PM

Most any DPDT 120V/240V AC relay can be wired up to do this. Two input plugs, one output plug. If plug A has power, it will turn on the relay and route plug A to the output plug. If not, the the relay will drop and plug B will be connected to the output.

In general, I'm going to guess that the power draw of a filter pump is based largely on how much resistance the filter has to flow. So large filters should be able to get the same GPM with a smaller pump.

Jon,

Using the relay as the switch, would that not cause relay points arcing if the pump is running when the sun gets shaded lets say.  It would seem like a soft-start. soft-stop (transfer) would be better for the pump/relay.

Based on my research, a larger filter (at least 50% over-sized), larger diameter piping and less 90 degree bends in the piping...45 degree bends better, would need a smaller pump.

I think that running an inverter without a battery would be a problem for clouds and for motor startup. No battery + variable speed drive and slow start might be OK. But then you need some smarter logic to decide when to switch to mains power.

I'd run a 2x or 3x oversized filter and pipes in areas where the power is very expensive.

Hey Jon, what about just using a Grid-Tie Inverter and pumping 200-400 watts back into the house? The pool pump would be running off home A/C as normal, but you would be supplementing that power with the solar/grid-tie.

Would that work?

That sounds easy. Use a timer on the pump so it runs at midday (when you are most likely to have solar power).

My thoughts...sometimes we all over-think things ;-)

Also, when it sounds easy...I always wonder

I would go the solar grid tie route and just set the timer to run at the times you usually have sun and would be back-feeding the grid anyway. You will get the most efficient system this way, no batteries to maintain or have loss with. And if your panels are putting out any power it will all be used by the home in some way, not just when they are getting full sun and could power the pump directly.

Brock,

Thanks..that is what I'm leaning toward.  I can get 1KW of panels ($1000), 1.5 kW transformerless high eff inverter ($700) and power my pool pump most of the day (except maybe if the spa is on)..but I can always add a few more panels when I get the $$$.  Plus, during low speed pump usage..I would offset my home usage.

Do you have any info on SunRay 3 phase DC solar pumps (lorentz pfd600)?  Are DC pumps more eff than VFD Pumps?

The most efficient (kwh/gal) pump is one sized for the exact pressure and gpm needed and without extra electronics.

jonr,

I believe your correct..however, when their are spas, solar water heater collectors on a roof etc..etc...pump demands can vary. So the newer VFD pumps appear to be the best of both worlds. Granted..more to go wrong. But in the old way of doing it..using a single speed pump...the installer would have to determine the greatest flow/PSI needed..worst case scenario..then buffer a plumbing/degradation factor and install the appropriate pump. Unfortunately, that is typically too big for most of the day's usage (filtration/salt-chlorine generation) ...based off my research and understanding

I agree. If you need two levels of gpm/psi then two pumps will beat a VFD. If load is all over the place, then a VFD makes sense.

Posted By jonr on 01 Aug 2012 03:53 PM
I agree. If you need two levels of gpm/psi then two pumps will beat a VFD. If load is all over the place, then a VFD makes sense.

Except when you have to purchase the second pump

Aloha Brock, I am the Lorentz Distributor for the Hawaii Islands and I will tell you that sized and installed properly Lorentz will provide you with all the power you need for a perfect pool. On July 28TH we just opened the first commercial swimming pool that is completely powered by the sun. 48 Trina 185 watt modules power 3 PS1800 Lorentz Pool Pumps without any AC power or back up. According to the Health Department we needed to turn the entire volume of water (105,00 gallons) every 6 hours. We accomplished this and made history when we started up this new system on July 28Th, 2012 @ 8:30 in the morning. At 8:31 a.m. we were pumping 115 gallons per minute per pump. That is 345 gallons per minute, 20,700 gallons per hour and 124,200 every six hours which exceeds our needs. So as you can see it is very possible. If you have any questions you can always call me and I can help you or direct you to an installer near you. Mahalo, Michael

Circulating your swimming pool water 24 hours a day is significant part of your electricity bill during the swimming season? A high volume DC solar pump can run solar panel direct during daylight hours to keep your pool in good condition with no energy expense.
The AC pump is on the right and is available for backup on cloudy or overcast days if needed.
For further info about solar power pump you have to visit polygroup which is the better place.

There are two basic types SWH systems, passive and active. In both, water is heated in a solar collector which is usually a flat, insulated box with a glass plate on top and a metal plate at the bottom with copper pipe inside. The efficiency of both systems is about the same and each has its advantages and disadvantages.No pump is required in a passive system. The tank also contains an electric backup heating element to heat water.