(Continued from Part 1. This part concludes the article.)
The #1303 model of Dankoff Slow pumps has the highest ‘gpm’ (gallon per minute) rating of the less expensive 1300 series. The #1303-24 pumps the most water for the money, and to a height that it will pump that is adequate for most situations. The advantage of a 24 volt system over a 12 volt pump, is that most surface water sources would likely be in a shaded environment, so the panels would need to be located some distance from the water source to obtain the needed amount of sunshine. We should place the panels where the sun shines most to get the needed solar power output to pump the *maximum* amount of water for your individual requirement.
If we need 225 gallons per day, we only need sunshine for the time needed to pump that 225 gallon goal. More sun is not necessarily needed. For example, if the system as installed produces 1 mpg with full sun, and 225 gallons are needed, then 4 hours of full sun is required to produce 225 gallons. On cloudy days it will produce less. However, the garden will require less water on cloudy days. I use 20, or 55 gallon drums, and 40 gallon troughs to store water for times I would like to water the garden using the gravity fed method through a valve, or siphon effect, but slowly saturating, or flooding the garden could also be done. If enough water is held in reserve for cloudy days, one could just let the pump run and saturate the ground, but we would then be putting excessive time on the pump. It’s best not to expect the maximum output as solar conditions are usually less than optimal, so give your system a real world test, and see what it really does. We should estimate that the actual output will be less, therefore we should have built in, a wide margin of error just to make sure we can easily meet our greatest estimated requirement.Continue reading“My Solar-Powered Dankoff Slow Pump System – Part 2, by Tunnel Rabbit”