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pv powered pool pump

M

Mike Payne

Jan 1, 1970
0
Does anyone have any experience running a swimming pool pump directly off
PV? I currently have a 1Hp AC pump that is running 8-10 hours a day. It
occurred to me that switching this pump out for one that is powered directly
off PV would be the cheapest way to start using PV power. It wouldn't need
to be grid tied. It wouldn't need battery backup, etc.

It seemed silly to pay for a grid tie 1500watt PV system if the pool pump is
already pulling more power than it would generate.

Are there any negatives to my plan? Any guesses on what it would cost?

thanks again,

mike
 
S

SJC

Jan 1, 1970
0
Mike Payne said:
Does anyone have any experience running a swimming pool pump directly off
PV? I currently have a 1Hp AC pump that is running 8-10 hours a day. It
occurred to me that switching this pump out for one that is powered directly
off PV would be the cheapest way to start using PV power. It wouldn't need
to be grid tied. It wouldn't need battery backup, etc.

It seemed silly to pay for a grid tie 1500watt PV system if the pool pump is
already pulling more power than it would generate.

Are there any negatives to my plan? Any guesses on what it would cost?

thanks again,

mike

Hi Mike,

The group talked a bit about this with spa pumps and other
motors. The starting current is the big issue. If you are keeping
the existing motor, you have to have a way to meet the starting
current specification, which is usually a lot higher than running
current. You would probably need batteries to supply this current,
or have to pay for many more panels, which would be more
expensive and would not provide you with any run time when
cloudy.
 
M

Mike Payne

Jan 1, 1970
0
Would it work if I switched out the AC pump motor for a DC pump? Is the
only downside no pumping on cloudy days?

mike



Mike Payne said:
Does anyone have any experience running a swimming pool pump directly off
PV? I currently have a 1Hp AC pump that is running 8-10 hours a day. It
occurred to me that switching this pump out for one that is powered
directly
off PV would be the cheapest way to start using PV power. It wouldn't
need
to be grid tied. It wouldn't need battery backup, etc.

It seemed silly to pay for a grid tie 1500watt PV system if the pool pump
is
already pulling more power than it would generate.

Are there any negatives to my plan? Any guesses on what it would cost?

thanks again,

mike

Hi Mike,

The group talked a bit about this with spa pumps and other
motors. The starting current is the big issue. If you are keeping
the existing motor, you have to have a way to meet the starting
current specification, which is usually a lot higher than running
current. You would probably need batteries to supply this current,
or have to pay for many more panels, which would be more
expensive and would not provide you with any run time when
cloudy.
 
Mike Payne said:
Does anyone have any experience running a swimming pool pump directly off
PV? I currently have a 1Hp AC pump that is running 8-10 hours a day.
It occurred to me that switching this pump out for one that is powered
directly off PV would be the cheapest way to start using PV power. It
wouldn't need to be grid tied. It wouldn't need battery backup, etc.

I hadn't thought about the pool pump itself, which I run at night if I'm
not in the pool, but I did want to add a solar heat system for the pool.
It seemed natural to me that solar power for a pump for solar heat went
hand in hand, but the feedback that I get is that the solar system needed
for the pump would be too large to be economical as a standalone system.

Converting a domestic water supply pump to solar usually involves a greatly
reduced flow rate in a DC pump, instead of AC, and a storage tank. i don't
know if you can effectively reduce the flow rate for a normal pool pump.

A one horsepower pump draws at least 750 watts, more at startup.
My 1HP motor has a 9.0 Amp rating on the label.

That's a substantial solar system. You're asking for 6-8kWh per day.
I would guess $10,000 grid-tie, $15,000 off-grid. but what do I know? ;-)

If you go that big, why not do a grid-tie? Run the pump at night.
Then there might be some credits and rebates available, depending on where
you live.

You need some batteries, at least to smooth the startup current, if it's
a standalone system. A battery system could be handy in power outages as
well. Instead of running the pool, you could run household items.

http://www.green-trust.org/2003/pvsizing/default.htm
http://www.kyocerasolar.com/products/pv_calculator.html
 
S

SJC

Jan 1, 1970
0
Mike Payne said:
Would it work if I switched out the AC pump motor for a DC pump? Is the
only downside no pumping on cloudy days?

mike

There are large DC motors, but they require large start currents also.
If it were brushless DC, that is essentially a permanent magnet
AC motor and would require a special "soft start" vector controller
to keep the startup current managable. I would still think that you would
need batteries for take up the startup surge, but others may have more
experience in this area.
 
M

Mike Payne

Jan 1, 1970
0
The pool pump runs every day. If it doesn't you get algae gorwing pretty
quick in Florida. It just seemed like it would have to be thousands of
dollars cheaper to power a single DC pump then to tie into the grid. that
was my thinking anyway.

Isn't that what's solar PV is routinely used for? Powering water pumps for
cattle, etc.

mike
 
W

wmbjk

Jan 1, 1970
0
Does anyone have any experience running a swimming pool pump directly off
PV? I currently have a 1Hp AC pump that is running 8-10 hours a day. It
occurred to me that switching this pump out for one that is powered directly
off PV would be the cheapest way to start using PV power. It wouldn't need
to be grid tied. It wouldn't need battery backup, etc.

It seemed silly to pay for a grid tie 1500watt PV system if the pool pump is
already pulling more power than it would generate.

Are there any negatives to my plan? Any guesses on what it would cost?

thanks again,

mike

Perhaps you could adapt your system to use one of these
http://www.grundfos.com/web/homeus.nsf/Webopslag/85A210EAD5DF90C786256B7D005AF12F

Manual including curves
http://www.us.grundfos.com/web/Down...451057588256B7B005019AD/$File/L-SP-TL-014.pdf

You'll need to know the pressure and flow needs of the pool
filtration. Then check the curves to see which Flex model would fit
and how much PV it would need. The pump will cost about $1500US plus
plumbing. Perhaps as little as $1000 for sufficient PV. You could wire
it to run from AC if needed on sunless days.

Another option would be to swap out the current pump for a more
efficient AC powered one, which will look very much like the Flex but
adapted for surface use and horizontal mounting. They do make one, but
I couldn't find a link.

Wayne
 
B

Bill Kaszeta / Photovoltaic Resources

Jan 1, 1970
0
Does anyone have any experience running a swimming pool pump directly off
PV? I currently have a 1Hp AC pump that is running 8-10 hours a day. It
occurred to me that switching this pump out for one that is powered directly
off PV would be the cheapest way to start using PV power. It wouldn't need
to be grid tied. It wouldn't need battery backup, etc.

It seemed silly to pay for a grid tie 1500watt PV system if the pool pump is
already pulling more power than it would generate.

Are there any negatives to my plan? Any guesses on what it would cost?

thanks again,

mike
http://www.etaengineering.com/pool_pump/intro.shtml

http://www.sunpumps.com/ProductsCli...entrifugal Surface Pumps&ProductRootNodeId=54
Bill Kaszeta
Photovoltaic Resources Int'l
Tempe Arizona USA
[email protected]
 
Mike Payne said:
Isn't that what's solar PV is routinely used for? Powering water pumps for
cattle, etc.

The solar pumps produce a small flow of water, and have large holding
tanks. One steer drinks about 30 gallons per day, but you have all day to
pump that 30 gallons.

I think you need a higher flow rate than that in your pool.
 
S

SJC

Jan 1, 1970
0
Great links Bill.
One thing I notice on the second link is the motor.
It looks like a Leeson brush DC motor. I would think the
brushes would need replacing on a regular basis and the
armater may have a life issue, running 4 hours every day.
 
G

Gooey TARBALLS

Jan 1, 1970
0
Question: What is the capacity the POOL requires in GPM and PRESSURE (I
assume to push the pool water through the sand filter). It would seem that
you might want to investigate pumps/motors that will meet or exceed this
capacity and can be run off the DC available from the SOLAR PANELS. From my
reading, it looks like you would want to replace/bypass the existing pump
and motor and might need a battery and dc/dc converter to make it work
reliably.
 
M

Mike Payne

Jan 1, 1970
0
I think I may have finally hit on a very economical way for me to use solar
pv. According to the link below you can buy a kit to replace a 1 HP AC
pool pump for roughly $6000. The kit includes a DC Pool Pump, charge
controller, and 600 watts of PV panels to drive the pump. No batteries are
needed to help start the motor as others have suggested.

A 1 HP AC motor pulls close to 1500 watts. The federal government will
give me a $2000 tax credit for buying the system dropping my cost to $4000.
Because it isn't grid tied I won't need any permits or electricians and I
can do the installation myself.

My pool pump previously ran 8 hours a day, 365 days a year. As near as I
can calculate for $4000 I'm getting the equivalent of a 1500 watt grid tie
system for $4000. That seems like a pretty good deal to me.

My only concern is if we get a week of cloudy weather in August I would need
some back up pumping ability. But by plumbing the new DC pump in parallel
with the existing AC pump I can run the AC pump at night if extra pumping is
ever needed.

I couldn't have come up with this plan without the help of this group. So
thanks to everyone. I'll give you guys an update once it's up and running.

mike

Link to DC Pool Pump kit...

http://www.etaengineering.com/pool_pump/intro.shtml
 
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