I have been thinking about the solar option some more. For one thing solarhome.org pump is very inexpensive. I figure after shipping it may cost $50. Then I would need a well pressure tank. Funny thing is, I could buy the same AC pump I have now on eBay and just use the tank. I did not buy the first one that way because the eBay pumps are all returns. (replace return with, does not work.) Cost, less than $30. The total would be about the same.

About that wasted solar energy issue. A thought had occurred to me, I waste summer solar production right now with my solar lights! The pump draws almost 10 amps @ 50 psi. That is about 120 Watts. Better to think in amp hours any way. My battery is a 75 amp hour battery. But, I am sure the capacity is less with a higher current draw. My lights use about 2 amp hours per night, if I remember correctly. On a sunny day in the summer I replace 6 amp hours or more. That leaves me with an extra 4 amp hours.

Gallon calculations: This is a possible deal breaker. Lets say the little DC pump uses 8 amps @ 20 psi and produces 3 GPM. If I want to water 10,000 Sq. Ft. @ 1″, I need almost 6000 Gallons. I question this amount of water since when I do water my bill never shows that high. Let’s use a third of that. Beside if I need to water more than that means the sun is out more. 🙂 2000 Gallons @ 3 GPM = 10 hours! See the problem. 10  hours x 8 amps = 80 amp hours. i.e. Not going to happen.

Now what if I only watered the front yard. It may only be 3000 Sq. Ft. That would work out to be 3 hours using the same fudge factor. That would drain the battery by 3 hours x 8 amps = 24 Amp hours. Not unreasonable. But I could only water once a week.

All in all, I will stay with the AC pump. Sure it uses 700 Watts when running. But it pumps four times as much water.