Low Producing Well on Solar

In response to questions about how we mitigated risks of a low producing well while on solar, I prepared some notes.

We completed the setup to accommodate a low producing well with the storage and filtration we need. We drilled a 300’ well and only have an estimated one gallon per minute of production. If we maintain one gallon per minute (GPM) forever, we should have plenty, yielding 1,440 gallons per day – well in excess of what we’ll require. However, my concern is that it apparently is not uncommon for well production to decline over time; if we were at 80 GPM and decreased to 40 GPM, there still would be lots of production. However, if we are at one GPM and decrease from there, our well will be of minimal use; therefore, we tied in rainwater harvesting and storage.

Outside, we collect water from the pumphouse roof, pass it from the gutter to a first flush filter, and then feed it into two exterior connected IBC totes; we also connect those totes to the interior setup, but I'll need to add a pump to push the water through the filtration.

Inside the pumphouse, we have a sediment filter and water softener (non electric) which feeds two IBC totes and a recirculation pump which circulates water between those two totes and a UV filter. We have a submersible pump in the drilled well (220V), a submersible pump (120V) in one of the totes to extract water from the tote, and a recirculating pump (120V) to circulate the water. We also have a 50 gallon pressure tank for the well and a 30 gallon pressure tank for the IBC totes/pump. We have a float valve in the IBC tote to cut off incoming water once the totes are full; that way they won’t overflow.

Here is where it gets fun. To ensure the pump doesn’t go dry, we swapped the manual switch for a PumpSaver. It will run the well pump until the well loses pressure, and then it will shut the well pump off for just under four hours. During that time, the well pipe will fill back to the stagnant level (or close). After four hours, the PumpSaver will reactive the well pump to allow it to continue to pump water.

We also added a timer. My thought is that I don’t want the 220V well pump draining the solar batteries while filling the storage tanks through the night. Therefore, the timer will limit when the well pumps water. Here’s a scenario. Let’s say we use 450 gallons at night – lots of showers and watering animals. Our interior tanks store 550 gallons and therefore need to be filled. At 0730, the timer powers the well pump. The well pump pumps 350 gallons of water from the well pipe into the pumphouse where it is filtered and stored; that takes 45 minutes. Then the well runs dry. The PumpSaver shuts down the well pump for about four hours while the well pipe refills. Then the PumpSaver reactivates the well pump, and it resumes filling the IBC totes in the pumphouse until they’re full, or if we’ve consumed more water, until the well pipe is drained. In the evening, before we lose light, the timer will cut off power to the well pump until the next morning.

Using this approach, we can theoretically have three fills during sunlight hours: 0730-0815 (350 gallons); 1215-1300 (240 gallons); 1700-1745 (240 gallons). Note that we had a full refill of the well pipe overnight but only four hours of fill, a partial fill if you will), during the day. The 830 gallons of water we pull from the well each day should more than exceed our water requirements, but in the off chance that we need more on a given day, we can run the pump through the night to increase production. Or, we can tap into our rainwater harvest storage as well.

As we raise more buildings, I plan to increase our rainwater harvest collection, and once we prepare to relocate on site full time, I plan to add more interior water storage.

This approach accomplishes a number of objectives:

Stores water to accommodate low production well.
Minimizes 220V well pump run time to daylight hours to minimize solar battery use.
Uses pump saver to protect well pump while reactivating it with an up-to 225 minute timer.
Augments well storage with rainwater harvest storage in case well runs dry.
Uses filtration to treat the water for sediment, coliform, and hardness.
Uses water circulation to ensure water does not remain stagnant.

Why do you care and how does this impact your solar system? Well, in many places across the country water is in short supply and low producing wells are not terribly uncommon. This approach provides for a low producing well with filtration, storage, and minimized impact on solar batteries. The 220V well pump consumes a fair amount of power when in operation, and the timer can largely mitigate the impact to batteries without impacting the consumer – at all. The circulation pump and UV filter run on continuous 120V power but appear to have minimal consumption.