adjustable solar pump for feng shui fountain

[yentakaren]

I don't know what category this belongs in and don't know post it.compute_1

Don't know exactly how to describe what I need - (being I'm sooo inexperienced at tool wording), but we've been unsuccessful in purchasing a solar driven pump (approximate 90 pumps per minute??) that is adjustable (can go from 70 to 125) and can also go at night from a battery. So maybe it's a solar pump with battery. Anyway, the landscaping store said some people are able to make such a pump. Is this an impossible task.

[suemarkp]

I'd try the Yard & Garden or Electrical Existing Home forums.

What you want may exist, but there are some physics issues to overcome. You can certainly make one yourself if you know enough. A pump usually needs a fair amount of electricity, and running it off a small battery (like what is in a solar yard light) would be dead in less than a day. If you want to run this off the sun, you will need a rather large solar panel to provide the amount of electricity you need. To determine the panel size, you need to know the amp and volt needs of the pump motor. This would be most efficient with a 12VDC pump (automotive or marine) instead of the 120VAC ones (household power) that are much easier to buy. So this is the first difficult step -- find a pump that provides the required gallons per hour (GPH) for the height you need to pump your water (this is the "head pressure" typically measured in feet). Find the 12VDC pump with the lowest amp draw that will meet those requirements.

Lets say you find that 12 VDC pump and it draws 1 amp. This is 12 watts (volts * amps). To run this for 24 hours requires 288 watt-hours (12 * 24). For a battery, it would need to be able to supply 24 amp-hours (1 amp to the motor for 24 hours). Batteries don't live long if totally drained, so I'd look for a battery that has a capacity of at least 50 amp hours. I think we're getting into car battery size here, and a marine or RV "deep cycle" type of battery would be about right.

To charge your battery will require at least 300 watt-hours per day. But if you get one cloudy day, you'll drain the battery and damage it. So I would try to get at least 1000 watt-hours of solar power to charge the battery. If the sun shines for 8 hours a day, you will need a 125 watt solar panel. You should also get a voltage regulator to prevent overcharging the battery.

All of this equipment is going to be rather large and will cost over $500. If you can reduce the water pumping requirements (so a smaller pump can be used), that will shrink everything. If you work through this with real equipment instead of the guesses I have made, it will open your eyes at to what it really takes to generate meaningful electricity from the sun.