Can A Solar Pump Run Continuously?
Can RPS Solar Pumps run continuously, 24/7? It’s important to know that this question has different layers to it, and there are assumptions at play that need to be chatted through to make sure you are fully informed about what solar pumps can and cannot do. The long and short of it is, yes, solar pumps can run continuously, and under certain conditions can run 24/7. But, having the potential to run continuously into a pressure storage or tank versus running 24/7 to fill a lake or pond are two very different scenarios. In the first scenario, the pump isn’t actually running 24/7; it has the potential to run, and it’ll always turn on when it’s called to by a pressure switch or float valve, but it’s not outputting water throughout the day. Alternatively, there are pump projects like filling a lake where there’s never any downtime, and while with enough batteries and solar panels you could construct a pump that 99% of the time runs 24/7, your project would quickly become cost-prohibitive.
So what do the experts suggest? In the following case studies we’ll analyze different potential customer’s wants and needs, and suggest a product that makes the most sense to maximize run time, without breaking the bank. Remember, our technicians don’t make commission, so there’s no pressure to upsize you in ways that don’t make sense; our main desire is to get you a product that satisfies your needs.
Example 1: Dominic is running 50 cattle on family land. He’s got a 150’ well with water at 80’, pumping straight to a 1,500 gallon storage tank by the wellhead. He’s interested in solar, but is worried about cloudy days or cattle coming up to drink in the evening when the pump doesn’t run. Could we get him a 24/7 setup to make sure his cattle always have water?
Oftentimes when customers call asking for a 24/7 pumping setup, they’re actually not looking for a pump that runs 24/7, but rather their needs correspond more towards the first scenario written above, where there’s a potential for pumping. 50 cattle at a maximum will only need 1,000-1,500 Gallons per Day (GPD), and a conservative estimate of a solar pumping day is six hours, so at a minimum we’d be looking for a pump doing around 4 Gallons per Minute (GPM). At an 80’ static water level, our smallest pump does about 3 GPM, so let’s upgrade to the next size up, the RPS 400. This has the added benefit of some extra solar panels that could be put to use charging a 48V battery bank whenever the pump isn’t pumping. This battery bank allows for 1-2 hours of run time at night time. If Dominic is interested in more run time, he can purchase larger batteries, or buy extra panels and/or batteries at a later date. Customers really appreciate this modular approach to our pump kits; you can always purchase a system with no batteries, and then add on batteries or a generator/AC convertor at a later date. In this way, we can sell systems that align more closely with what our customers actually need, rather than selling a huge network of solar panels and batteries that aren’t necessary.
Example 2: Sarah is paying way too much on her power bill for her AC pump, and is also worried about potential grid collapse. She’s interested in one of our off-grid WaterSecure systems, and wants to learn more, but is worried she’d need a really big inverter to power her 3/4HP pump to allow it to run continuously. If she wants to make sure in an emergency she can reliably run her pump, as well as some lights or a phone charger, what WaterSecure option would we suggest?
Our Watersecure systems are incredibly useful, and while we advertise them primarily to run water pumps, they can reliably power most 110/220V appliances (though we never market them as a whole home solar solution). For a 3/4HP pump, we would normally recommend one of our 3K systems, which can easily handle the startup wattage of any 3/4HP AC pump. A couple lights and a phone charger are fairly negligible in terms of power output, so that wouldn’t affect any of our calculations. Sarah would just need to ensure she is comfortable with some extra wiring, since the Watersecure only comes with a 220V outlet for one water pump.
The Watersecure 3K-1200 (12x100W solar panels and 8x55Ah batteries) would be able to comfortably power Sarah’s pump and other appliances throughout a solar day, and then has roughly an additional four hours of battery backup on a full charge. Since house pumps aren’t running continuously, but rather are refilling a pressure tank, those four hours could last for multiple days through an emergency like a hurricane for example. Our inverters come with a handy display screen to keep track of battery charge, and of course on sunny days or when you regain access to AC power those batteries would charge right back up. If Sarah wanted to have more battery backup, we would just size her up a model to our 3K-1800.
Example 3: Johnny has a ⅛ acre pond, and wants to keep up with evaporation for his fish pond, as well as make sure the pond doesn’t become stagnant. He likes the idea of a true 24/7 pump setup, where a water pump from a nearby 50’ well pumps out a slow stream of water into the pond, with overflow outputting into a stream. He has no access to power, but really wants a 24/7 option, how can we help?
The first thing we would tell Johnny is that we will never sell a system that promises to pump water 24/7, 365 days a year. There are just too many factors to take into consideration, e.g. uncharacteristically cloudy weather for multiple weeks at a time. Nevertheless, the best option for Johnny is going to be a product we call the ‘Low and Slow Solar Kit’, which can be used in pumping or aeration scenarios. If Johnny buys our Pump/Power Train model, he would receive a 500W RPS pump, 12x100W panels, 12x55Ah batteries, as well as a charge controller, low and high water sensors. The RPS pump would be set to run at low volume, 1-2GPM, which on a standard sunny day would allow for 24 hours a day of pumping (~1,500 GPD); that would cover the evaporation losses of Johnny’s pond. There are other ways to solve Johnny’s pond issues, for example he could buy a small RPS200 pump to output water for 6-8 hours a day on average, and then an AIR200 aerator kit to oxygenate his pond. But if Johnny is set on 24/7 operation, the Low and Slow Kit will be the closest product we could offer him.
We don’t ever want to promise a result we’re not confident would occur with our pumps, that’s why we don’t promise 24/7 pumping on our products. Solar pumps rely on nature, which is inherently fickle. However, we find that many of our customers trust more in the reliability of the sun compared to the reliability of their power company! So if you have more thoughts or questions about solar pump reliability or durability, please chat with us at 888-637-4493 or through email at [email protected]. Our technicians are friendly, and again there’s no pressure to buy right away. We hope to hear from you soon, but until then have a great day!