A solar water pump is often the best choice for pumping outdoors or in remote locations where electricity simply isn’t an option. More and more frequently they are being used in gardens, agricultural irrigation, and even for borehole or well pumping in off-grid areas.
Of course, a solar water pump that creates a nice backyard water feature is going to have different specifications than a pump used by ranchers to water livestock from a borehole.
I’m going to take the chance that most EcoVillageGreen readers fit into the former rather than the latter and talk about what to look for in a solar water pump for domestic use.
Know your vertical lift and flow rates before you shop
All water pumps, regardless of whether they’re solar, are rated according to vertical lift and water flow rates. Vertical lift tells you how high the pump will be able to transport the water, for example from the base of a pond where the pump is located, to the top of a rock water fall. Water flow is pretty self explanatory and tells you how much water the pump can push through in an hour.
So, when you’re in the market for a solar water pump, make sure you know your vertical lift and flow demands first and also account for any long horizontal pipes as this will put increased demand on the pump too. The further the water has to be pumped, the harder the pump has to work.
Do you need a back-up plan?
Solar water pumps either come with a battery or not. So, it’s good to know before you buy whether you think you’ll need the pump to work on cloudy days or at night.
Pumps that come with batteries usually have two modes. When there’s full sun, the pump operates entirely off of the photovoltaic (PV) cells and any excess energy is stored in the batteries. At night, or on cloudy days, the pump is switched over to a night mode, which draws power from the battery rather than the PV cells.
If it’s not critical that your pump work at night or every day, such as a decorative fountain in the back garden, then there’s likely no need for the added environmental and financial cost of a pump with a battery.
A third option, of course, is to have a pump transfer water to a storage tank while it’s sunny. Then you can access the water at any time, but this is obviously useful for some pump projects.
Know the pros and cons of going solar
It’s a wonderful thing to make use of free clean energy from the sun, but as always, there are drawbacks as well as advantages with every technology. It will really depend on the project and your budget as to whether solar is the best option. Here’s a quick list of pros and cons to help you decide:
- Solar is a clean, renewable energy. Using solar means there are no emissions associated with the running of the technology.
- Solar is free so after the initial investment, there is no cost to run the pump, other than standard maintenance.
- There is no wiring involved. Most solar water pumps are extremely straightforward to install, so anyone can do it. They also give you the flexibility of having a water pump where electricity isn’t available, or at least not without dragging a big extension cord across your lawn!
- Some solar water pumps may be eligible for tax credits in some states. For example, some solar pool and spa pumps are eligible, which provides considerable financial incentive for going solar.
- In looking at feedback from owners of solar water pumps, it seems that they are often far more under-powered than people hope. It really is a case of you get what you pay for, and the powerful solar pumps are going to cost quite a bit more.
- The strength of the pump is often directly related to the strength of the sunlight. If you need consistent flow for long periods of time, it might be wise to get a system that either has battery back-up or can also be wired-in for days when the sun is less reliable.
- Solar pumps don’t operate at night or, depending on the solar panel, when it’s cloudy. This comes back to what I said in the last point, in that if you need consistent flow, you might need a back-up plan for your solar.
Of course, for many water pump uses, these cons can easily be overlooked. For instance, it’s not exactly vital that a water fountain in the backyard be pumping water every hour of every day. However, if the pump is aerating a pond with live fish, these cons may be more serious.
Some products to take a look at:
Here are a few products to get you started on your shopping comparisons. I’ve listed them in order of increasing power (and subsequently increasing price) so if you’re looking for something for birds to splash around in the backyard, you’ll be looking at the top of the list…pool owners are at the bottom.
Beckett water garden solar pump – this little pump has a 1.3-watt solar panel and comes with 10 different nozzle types. It has a vertical water lift of 18” and puts out 75 gallons per hour. There’s no back up battery, so it’s only on when the sun’s out, but it’s decent at the price of $51.34 USD.
A 3-watt solar powered water fountain pump that comes with ten feet of cable so the solar panel can be placed to take advantage of full sun. This version does come with a battery and also has an auto on/off feature that switches the pump off after dark when the battery runs low and starts it back up when the sun comes out the following day. It has a vertical water lift max of 5 feet and has a maximum water flow of 100 gallons per hour. It costs around $71 USD.
This 8-watt water solar pump makes a fountain out of any pond. It has 4 different water flow settings and an LED fountain light that shines on the water spray. Like the previous pump, this one also comes with a battery back-up. It has two modes, day mode and night mode. In day mode the pump runs from solar energy alone and any excess energy produced by the PV cells is fed into the battery. On this mode, pump performance is directly related to sun exposure. Night mode should be used on overcast days or at night as the pump draws energy from the battery rather than the PV cells. Unfortunately I couldn’t find any information regarding flow rate or water lift, but it costs $137.20 USD.
The 20 Watt solar panel water fountain pump by GTMax is starting to get into the more serious pumps. It has a variable speed valve as well as a battery. It’s vertical water lift is 6.5 feet and water flow is 341 gallons per hour. It will run you around $226.18 USD.
The Instapark GYD-0030 has a 30 watt solar panel and the pump has a vertical water lift of 6.5 feet. It can push through 208 gallons per hour and it comes with a 2 year warranty. There’s no battery though and it costs more than the GTMax pump at $274.20 USD.
The Instapark GYD-0050 Solar–powered water pump is one of the bigger ones you will find. It has a 50 watt solar panel, which drives the pump to a maximum flow rate of 520 gallons per hour. It comes with a 2-year warranty, a 10’ connection cord, and three different spray nozzles. It has one of the better vertical lifts at 10.5 feet and doesn’t come with a battery. It costs $399.50 USD.
The Savior Solar Pool Filter is obviously a pool filter and not just a pump for your fishpond. It has a flow rate of 1,100 gallons per hour and uses a 55 watt solar panel. This product is made in the US. It costs $750 USD, but the retailer claims that it will pay for itself in 7 months as there is no cost to running the pump once it’s installed. There are no batteries.
A solar water pump is a nice option given the clear environmental benefits. However, you have to carefully consider what you need out of the pump, before you decide that solar is the best choice for the project. Buying something that doesn’t do what you need it to isn’t great for the environment or your wallet.
Now, because I didn’t talk about solar pumps in a broader context (i.e. beyond the backyard), I thought I would leave you with this little video. This is Professor Thomas Jenkins from New Mexico State University discussing the advantages of a solar water pump for agricultural purposes in southern New Mexico.