Solar panels & battery powering a pond pump and LED lights

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  • cider_powered
    Junior Member
    • Feb 2019
    • 4
    #1

    Solar panels & battery powering a pond pump and LED lights

    Hi everyone, I am new to solar and new to here.

    I read through most of the threads already in this Solar water pumps section back to 2015 and have learned a lot, I learnt that connecting solar panels directly to a pond pump is not a good idea because it can over supply voltage and cook the motor thus reducing pump life expectancy and also that you can prevent this by putting putting in a switch, I have a couple questions.

    I am about to start a new project making an outdoor pond, the pond will feature a waterfall (supplied by a pond pump) and LED lights for night time. I don't want to connect the water pump and LED lights to the mains power as power is not cheap where I am from and the sun is free so naturally I want to power it with solar. What I was wondering is what is my best option, I would like to install the solar panel that feeds to a battery because obviously the sun is not always shinning, the pump and LED lights can feed off the battery, what I am wondering what is a good option, I have seen a few solar panel and battery kits on Ebay, but I am not sure if I should trust these or even know if they are up to the task? When the sun is shinning is it possible to have the pump running directly off the solar panels and then switching over to battery power when there's no sun? The pump wattage is 165.

    Take note the LED lights would obviously only be on at night time and to be honest would really on be switched on a Friday/Sat/Sun night and maybe every now and then during the week night. The pump also would be running all day and into most of the night, but I would have it timed to switch off around 8-9pm, which comes to my next question, what is a good option for having a timer switch to switch the pump on an off at a set time?

    Thank you so much for any replies and I am excited I finally found a forum that is dedicated to solar!
    Tags: None
    • SunEagle
      Super Moderator
      • Oct 2012
      • 15126
      #2
      Hello cider_powered and welcome to Solar Panel Talk

      Just to help you understand the cost of generating electricity from a solar / battery system. When you figure the cost of the solar equipment and battery along with the life of that battery you can usually calculate it will cost over $1 to generate a kWh. While some areas have expensive electricity I seriously doubt you are paying the POCO $1/kWh. So please don't be surprised if you do not really save any money.

      To determine the size of the battery you have to know how many watt hours it will run the loads. This will be based on some days you will not get any useful sunlight for the panel.

      Once you have figured how many daily watt hours you need you can calculate the battery size. On average it can cost about $1500 for each daily kWh your system needs to produce. That pump may use almost 4kWh a day (165w x 24 hours = 3.96kWh) so your small system may be quite expensive.

        Comment

        • cider_powered
          Junior Member
          • Feb 2019
          • 4
          #3
          Thank you for the reply SunEagle!

          So in other words it's probably cheaper to just run the pump off the mains power rather than try and solar power it? Is there a way to find out how much power a particular pond pump will use, I would be very interested to know what the daily running cost would be? I have heard of claims that most pond pumps cost as little as what a light bulb costs to run, would this be accurate or just a selling gimmick?

            Comment

            • azdave
              Moderator
              • Oct 2014
              • 765
              #4
              Originally posted by cider_powered
              Is there a way to find out how much power a particular pond pump will use, I would be very interested to know what the daily running cost would be? I have heard of claims that most pond pumps cost as little as what a light bulb costs to run, would this be accurate or just a selling gimmick?
              Any pond pump (from a little bird bath sized pump to a large waterfall pump) should have specs on the power consumption clearly listed for you. Many smaller pumps draw less than an old 60W light bulb but those pumps are not used to build impressive waterfalls or circulate huge amounts of water. We have no idea what size pond and waterfall you are planning so it is hard to know what you are planning. Is it the size of a bathtub? A 4-person hot tub? Bigger?

              At any size, I would not go to the expense and trouble of trying to use solar power to run the project if you can power it off the mains.

              Dave W. Gilbert AZ
              6.63kW grid-tie owner

                Comment

                • J.P.M.
                  Solar Fanatic
                  • Aug 2013
                  • 14939
                  #5
                  Originally posted by azdave

                  Any pond pump (from a little bird bath sized pump to a large waterfall pump) should have specs on the power consumption clearly listed for you. Many smaller pumps draw less than an old 60W light bulb but those pumps are not used to build impressive waterfalls or circulate huge amounts of water. We have no idea what size pond and waterfall you are planning so it is hard to know what you are planning. Is it the size of a bathtub? A 4-person hot tub? Bigger?

                  At any size, I would not go to the expense and trouble of trying to use solar power to run the project if you can power it off the mains.
                  +1, but the OP being new to solar and maybe full of wide eyed optimism and thinking media hype = reality will either take your the advice or find out the hard way.

                    Comment

                    • cider_powered
                      Junior Member
                      • Feb 2019
                      • 4
                      #6
                      Originally posted by azdave

                      Any pond pump (from a little bird bath sized pump to a large waterfall pump) should have specs on the power consumption clearly listed for you. Many smaller pumps draw less than an old 60W light bulb but those pumps are not used to build impressive waterfalls or circulate huge amounts of water. We have no idea what size pond and waterfall you are planning so it is hard to know what you are planning. Is it the size of a bathtub? A 4-person hot tub? Bigger?

                      At any size, I would not go to the expense and trouble of trying to use solar power to run the project if you can power it off the mains.
                      Thank you for the reply, I will find the specs of the pump and see what I can decipher.

                        Comment

                        • cider_powered
                          Junior Member
                          • Feb 2019
                          • 4
                          #7
                          Originally posted by J.P.M.

                          +1, but the OP being new to solar and maybe full of wide eyed optimism and thinking media hype = reality will either take your the advice or find out the hard way.
                          You are spot on the money, reading through a lot of posts on here I can see that solar power does have its limitations, it certainly has a future as the technology improves and the costs come down in price, but for the smaller projects like I am embarking on it seems that mains power is the way to go when you break down the costs of a solar setup.

                            Comment

                            • J.P.M.
                              Solar Fanatic
                              • Aug 2013
                              • 14939
                              #8
                              Originally posted by cider_powered

                              You are spot on the money, reading through a lot of posts on here I can see that solar power does have its limitations, it certainly has a future as the technology improves and the costs come down in price, but for the smaller projects like I am embarking on it seems that mains power is the way to go when you break down the costs of a solar setup.
                              Well, (and certainly not because you seem to agree with me), you're one on the more critical thinking newbies to show up here. Something to consider: Open brain before opening wallet.

                              FWIW, and not trying to sound like a luddite, and as an opinion only, but most of the real technology improvements - as opposed to those incremental changes in system design and tweaks that con men and peddlers claim as "revolutionary" or some such B.S. to take advantage of most folks' solar ignorance - have already been made, at least for what looks like the reasonably short near term.

                              Alternate energy, and solar energy in particular, does have a lot of promise, but it also has limitations, many - but not all of them - brought about as a result of not being the same animal as the mostly fossil fuel origined systems power systems we're familiar with.

                              As always, Caveat Emptor rules.

                              Add: Welcome to the neighborhood and the forum of few(er) illusions.

                                Comment

                                • J.P.M.
                                  Solar Fanatic
                                  • Aug 2013
                                  • 14939
                                  #9
                                  Originally posted by cider_powered
                                  Thank you for the reply SunEagle!

                                  So in other words it's probably cheaper to just run the pump off the mains power rather than try and solar power it? Is there a way to find out how much power a particular pond pump will use, I would be very interested to know what the daily running cost would be?
                                  Yes. You wrote 165 watts ? Most pumps have running watts listed on the pump nameplate. Or, Google "Kill-a-Watt". Get one and use it to find the pump running watts. Multiply by the expected hours of operation, divide that product by 1,000 and the result will be a pretty good approx., in kWh, of electrical energy the pump will use for that many hours of operation. For how much money that much electricity will set you back, multiply that usage by your per kWh electricity cost during pump operation time (s) (that cost may well be different at different times, depending on how much electricity you use per billing period as well as when you use the pump) and you will have a rough idea of the cost of electricity to operate the pump.

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