Looking for a simple design to run a small pool pump while the sun is shining

gtojohn

I would like to solar power a pump I already have.This is the motor and specs http://www.centuryelectricmotor.com/MotorCategory.aspx?LangType=1033&id=362
. High speed is 3/4 hp low is 1/10 hp. There is very little resistance to flow, my plumbing is 2", sized for a 1.5 hp pump, my filter is also huge and generally shows less than 2psi resistance. In theory I would like to put a couple of panels together with a 1000watt low frequency inverter. When the sun shines the pump runs. Run time for my pool shouldn't be a problem . Last year I managed to keep the pool relatively clean by only running it only on the weekends and when we were in the pool. I haven't seen any plans that don't use batteries. Are they essential? Can I put a charge controller in front of my inverter without battery without issue?

gtojohn

That motor is the B2981 the 115v model.

BB.

To be honest, there is no simple solar/DC water pump solutions.

DC pumps either use brushed motors (can be efficient, but short brush/motor life) or more complex motors (electronics, 3 phase/PM 3 phase motors, etc.).

If you want to use single phase 115 VAC motor--Then you can use an off grid solar power system (panels + charge controller + batteries + AC inverter). Or you can use a Grid Tied system (solar panels + GT inverter + building permits + Utility Approval/Billing plan).

From a hardware point of view, a GT system is about 1/4 the cost of hardware (even as high as 1/10th the cost) vs an off grid battery system.

So... Is the pool off grid or do you have utility power?

If you have utility power, then figuring out the right size pump / pump type (pick efficient type with inlet below water level) and an efficient two speed motor or VFD type setup (variable frequency drive) to allow you to spin the pump at the "correct" RPM for your needs (cleaning, swimming, night, etc.) is probably your correct choice.

If you want/need completely off grid power, then picking a pump that is designed to work with directly with solar panels can work well--But you are looking at some pretty expensive pumps (typically have internal electronics/VFD with MPPT type input/PM Motor, etc.).

http://www.solar-electric.com/wind-and-water-products/sodcwapu/grsoposuwapu/grsqpu.html
http://www.solar-electric.com/wind-and-water-products/sodcwapu/grsoposuwapu/grcrisesupu.html
http://www.solarpumps.com/flow-chart-ranch-pump.html

The above pumps are "simple" to run (solar panels, some will take AC power sources for backup, etc.). But it will cost you several thousands of dollars for the privilege.

If you want to look at some of the newer solutions (solar VFD + Three Phase Motors), here is some interesting reading (probably most are too large for your needs, but still can learn):

WELL PUMP and Inverter QUESTION
Wind/solar for large scale pumping etc (out of my depth!)
could use knowledge - using Gould jet pump - transfering from 230vAC to ? DC
Help required to design off grid system

There are probably lower cost direct solar solutions out there (China and others seem to be offering solar VFD devices)--But you will need to do some research.

Note that running induction motors with VFDs may have their own issues (many VFDs are MSW--Modified Square Wave inverters, which can be hard on AC motors). Lots of reading ahead (I don't have any quick/easy solutions that I have seen).

-Bill

gtojohn

The house is on the grid. Due to permiting requirements. Id rather not grid tie my house. Yes freq drives are awesome things, however the motor i already have is a nice, efficient motor which is a great size for what i need. Return and supply are at same height so no real head pressure beyond my oversized filter and piping. At low speed the motor draws about 100 watts. High speed is about 500 watts. Would it be possible to string together 800 watts of panels together with a mppt charge controller and battery just as a dummy load tied together with a cheap chinese 1200 watt inverter? Maybe a timer for the pump calling during peak sunlight? Seems like hardware wise it could be done for less than a vfd motor and it 'll have free power until i smoke my Chinese inverter.

Brlux

Until a cloud passes by and you drain your battery, do that a few times and you will be needing a new battery. If something were to work well in a stand alone application it seems like it would need to be able to modulate the motor output with relation to the actual incoming power.

If you really want a simple system that will work well the best solution is grid tie.

BB.

There are several guys with youtube videos where they connect a solar array directly to the 12 VDC input AC inverter. And (at least) one guy found he had to put a relay in the DC input to "reset" the inverter when the array "browned out" (his inverter would not restart without removing DC power first).

The major problem is most DC input inverters have a relatively narrow working voltage range of 10.5 to 15/16 volts. And a typical "12 vdc" solar panel runs from zero to ~18 volts Vmp to ~21 volts Voc.

If you can find a DC input inverter that will run reliably from a solar array--Yea, it could work and do what you need for a reasonable amount of money. You just need to "oversize" the panel to supply enough starting power for the motor/inverter.

There have been a lot of people that have asked for this type of AC inverter direct to AC motor function--And it can make a lot of sense for things like pumping water. Not sure why there are not inverters on the market that support this function (given how "cheap" solar panels are these days).

-Bill

gtojohn

Thanks for the resposes. And thanks for bearing with my inexperience. I have seen a pool filter that used solar to run a marine bilge pump, but very primative. Really i dpn't want to run the pump with the battery, just help regulate the brown outs. The mppt charger should help keep the minimal voltage through the inverter. Maybe a dc relay to engage a motor contactor at a desired voltage. Pv still generates on a cloudy day so it would seems i could at least run at low speed. I guess its all about the controls...

Brlux

Seems like there could be a real market for a Solar MPPT VFD that could be used to drive 3 phase / BDC motors at the maximum load that the attached solar will support. You could add it to a Hayward or Pentair variable speed pool pump.

Ideally it would have dual power input for solar and AC mains. You could set a minimum turnover and whatever can not be accomplished on solar will be finished on AC. There will also be needs for cleaning that the solar may not be up to and the AC would be needed to accomplish.

On a side note I have a Hayward Ecostar variable speed and the motor efficiency is amazing. My old pump was 2500W and ran for 5-6 hours a day and still was struggling to keep the pool clean on that schedule. The Ecostar runs at 120W for 20 hours and 1000W for 1 hour a day and my pool has never been cleaner. As efficient as my pump is at moving water it surprisingly uses 23W when the pump is off and the screen back light is on 24/7. I have only looked at the screen after dark a hand full of times. It should have an off power draw of less than 1W. I assume the logic also draws a similar power when on so about 1/5 of my 120W pumping power is lost on running the electronics.

BB.

They are out there:

http://www.schneider-electric.com/products/ww/en/2900-motion-drives/2945-specialized-drives/61444-altivar-312-solar/

And I have seen a lot of them advertized from China.

I don't know how available/cost of these guys.

-Bill

Dave Angelini

BB. wrote: »

They are out there:

http://www.schneider-electric.com/pr...var-312-solar/

And I have seen a lot of them advertized from China.

I don't know how available/cost of these guys.

-Bill

I found some at Zoro tools who have been good to me.
They also have some for single phase applications.

http://www.zoro.com/g/Altivar%20312%...ives/00095366/

But, it looks like these are not the DC input models.... Hmmm...