simple question on watts & HP

[LaurelRT]

I'm sure asking this question here is a bit of overkill, but I hope someone will point me in the right direction.

I hope to use an automatic fly spray system with either a 0.33 or 0.5 HP moter to control mosquitoes in a small three sided shed for horses. The shed is farther from the main barn than the property owner wants to run electricity, so I am investigating solar energy.

How do I calculate the watts needed to run a motor of this size, and possibly a light bulb periodically? The motor would run for 45 to 60 seconds, about once every 3 to 4 hours.

Is this all I need to estimate to select a solar panal and battery system?

Thanks for your time on such a low tech question,
Laurel

 

[itsmoked]

I will first point out that 0.5HP would pump a helluva lot of fly spray. I would think about 30 gallons per minute.

So is this correct?

Otherwise you would use 746Watts per HP.

You figure the required Watts.
Then the time these Watts are called for.
Then these two numbers give you the watt-hours.
The watt-hours are what your solar panels must provide.

Solar panels are absurdly expensive and only work in sunlight so you need some battery capacity. The solar panels must be capable of providing about 150% of your watt-hours consumed by the pump.

The batteries must be sized so after the longest typical cloudy period the system can still function.

Other points include never discharging the batteries more than 50%. More and the battery life will plummet.

You would need an inverter to convert the battery power to what the motor requires. Including the starting current!

The creation of a solar system to run your system while not difficult really requires a lot of details and none of them can be skipped.

I would guess you are talking about at least $900 minimum.
A trench job might be much cheaper in the long run.

Or spend more on a very low power system that would ease the entire solar system design.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[davidbeach]

Don't forget that motors of this size have ridiculously low efficiencies, so it may take up to 2W into the motor to get 1W worth of power at the shaft.

 

[waross]

I agree with the previous posts and would add;
A DC motor would save the expense of an inverter. As well as first cost saving you would avoid the losses of the inverter.
respectfully

 

[LaurelRT]

Thank you very much for the information!

As for the size of the motor, I got 0.5HP from the information on the fly spray system retailer web site. The 0.5HP was for the large system, which may have, say 50+ nozzels runnning, and maybe 150ft or more of line, so 30 gal/min seems reasonable. Since I was considering scavanging parts from another system, I thought I might use a large motor.

While I realize that trenching electric would be more cost effective, I am not the owner of the property, and the sprayer would only benifit my horses. Since my family is military, and moving again in a few years, I would not recoup enough of the initial cost before leaving my investment. I thought a solar system would be "portable."

When I looked at solar panals, I couldn't appreciate how ridiculously expensive they would be, since I had no idea what to consider! Thanks again for the information. Perhaps I can figure out a creative alternative.

 

[itsmoked]

Let me suggest you get a couple of these.

http://www.groworganic.com/item_PIT950_PVFSWoodFlyTrap12x12x12.html?pMode=HiRes

Our free range chickens can generate clouds of flies. We finally got fed up and looked for a non poisonous environmentally sound solution. I would prefer not to spray gallons of poison everywhere. We have one of these and it is astounding! It fills up with flies quickly, piles, and piles, of them!! Our fly problem dropped to a non-problem.

You could buy one and duplicate them if you are handy. You bait them with some smelly yeast mix that you mix up and ferment. You could other things too like place one over a deep hole you shovel horse dung into. Part of the device's effectiveness is the Par-Tee mentality of flies. There can be two piles of something they like but they will all go where the others are. They attract each other BIG TIME.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[OperaHouse]

I bought a pair of solar panels retail a couple years ago before just before Europe started buying just about everyone made. I thought increased volume would lower the price! Today used panels on ebay are more than I paid for new. I thought there would be a bunch of slightly below grade to hit the market.

The camp never worked out. I figured 150W in panels to run just a 50W high eff fridge 20% duty cycle. I went days generating less than 2A in summer when I should have 10A. Any wisp of a cloud drops output to nothing.

 

[BJC]

IF you go solar you will no doubt have to ahve a battery as well as a solar cell. Most mosquitos seem to be out at night.
I would consider buying the 12 volt system, a couple of deep cycle boat batteries ( the kind they use on trolling motors) and a small cart.
Charge the batteries where you have power and change them out every day or so. Having horses is all about work so what,s a little more?

 

[itsmoked]

Yeah Opera! They keep feeding us that storey don't they!!! More! more! will equal cheaper! Cheaper! BUNK!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

Keith,
Side note on your organic fly catcher.
An acquaintance has a trout pond at his manufacturing plant for he and his employees like to fly fish at lunch. There is a dairy nearby so they were plagued by flies. He built one like this on a float in the trout pond with the bait suspended on wires. The flies go in for the bait and can't get out, but eventually tire and fall in the water, feeding his trout! His bait for the flies? Trout guts!

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[itsmoked]

That's a great use of flies!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[electricpete]

There's got to be something like a fly diode or a fly check valve in there. How does that work?

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[waross]

Further to BJC's suggestion;
I had a boat for a few years with twin 20 HP outboards.
I put electric starts on both, but they engines lacked charging circuits. I used a 12 volt car battery to start both engines and it would last all season. Do the numbers. It may work well for you. Then again, itsmoked's suggestion may work even better.
respectfully