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Hi, I'm new here. I have a solar powered off grid pond, and I want one of my pond pumps to only come on when the suns out. Can I hook the pump directly to the solar panel, before the charge controller? The solar panel is 100 watt and the pump uses around 50 watts. If I hook the pump up to the panel, before the charge controller, will the excess power not used by the pump go into the charge controller and batteries? Or will ot cause some sort of system problems? I have had no problems just hooking the panel right to the pump, it works fine, but then there is a lot of wasted power and if possible I'd like to send the unused power to my charge controller and batteries. Thanks for any help
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I see 2 problems with that.
The first is that your pump may not like the voltage the solar panel puts out. A 100 watt panel usually has a Vmp around 18vDC and can see as much as 22vDC for a Voc. That pump may not like that high a voltage and burn up.
Second. If you use up half or more of your panel wattage running the pump then you have very little left to charge any battery through a Charge controller.
A better solution would be to wire the 100 watt panel to the charge controller and then the CC to a 12volt 50Ah battery. You can then power your pump from your battery using a timer or photo cell that will only turn on when there is sunlight hitting it.
There are also some quality Charge controllers that have higher rated Load Terminals that will allow you to run DC loads at battery voltage as well as use the control logic in the CC to turn the load on and off via timer or some other sequence. -
I am not an expert, but I would say hooking it up after as intended is the best thing to do. The MPPT charge controller (You didn't specify the type) varies the impedance on the panels to always get the most power out of them. Placing a motor in between has GOT to be a bad idea.
The "wasted power" you speak of is usually sent to the battery, but if you aren't using batteries, then don't sweat the excess power. That's my guess.
Not to dissuade you, but all I have heard here is that pumps and solar are not a good combo. I have an Aquaponics system that I want to go solar with, but I have yet to ask here the best way to do that, since I currently have a water and an air pump.
There has to be a better way of controlling the duty cycle of the pump.
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It won't work as you expect it to for several reasons, as others have explained.
Why not replace the charge controller with a cheap load-control charge controller? They can be had from $10-$20 and contain an output that you can program to do things like "only turn it on when the sun is out."
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Thanks everyone for the replies. Its a harborfreight 12v sump pump, I'll have to look up what its V operating range is. Right now my 12v solar power system consists of a 205 watt panel hooked up to a Specialty Concepts ASC 16A charge controller which is hooked up to 4 costco 6v golf cart batteries, wired two in series to make to 12v battery banks wired in parrallel.
I guess what I'll do is just order the 100watt panel with another charge controller( my current charge controler is maxed out with the 200w panel) and hook it up to the same battery bank, so each panel has its own charge controller. Then I'll run the pump off the battery bank with some sort of sun timer as suggested.
I disaggree that solar and water pumps don't work together. The difficult thing is finding a 12v pump that lasts, for efficiency, but one can always just use an inverter and regular pumps just fine at the expense of efficiency, just use more solar panels. The harbor freight 12v pumps work great and pump over 500gph with about 60 watts. They just don't last very long, but at $20, even if I have to replace it every 4-6 months thats fine with me. Just have to always have a backup pump ready to go if it fails early. I'm also using a second smaller 24v ebay 120 gph pump that uses 25 watts with a supposedly 30,000 hr life span as a secondary pump. If the main pump goes out, the second pump will still provide some flow. I'm on the hunt for better pumps, but this is working well for now.Comment
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The reason I need the 100watt panel is because with other power loads the 205 watt panel isnt enough to run everything. I also wanted to run a pump directly off a panel for extra reliability incase something in the system fails so my fish wont die if I'm away.
I'm slowly going to add more panels so hopefuly I'll soon have at least 800watts or more in panels. The 24v 120gph ebay pumps work great directly connected to a solar panel, and the voltage is perfect, doesnt over run the pump. I think eventually, I'll have two or 3 of these pumps hooked directly to a 100 watt panel on a separate power system with no batteries, and then have my 500gph harborfreight pump going off the battery bank. I also want to experiment with having an insanely large bio filter in addition to having tons of plants in separate plant only ponds that are plumbed into the fish pond so water circulates through all.Comment
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n8r, if you get this to work the way you want, can you share the details of your system? I have an IBC Aquaponics setup, and I would love to run mine completely on solar. I have about 60W between air and water pumps right now, and a 750 APC UPS that got me through the several hour power outage storm in VA a few weeks ago. I have yet to run a network cable to the UPS to see what the actual outage looked like to the UPS, but to me it was too close, regardless. Hehe
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Something to think about. When the sun don't shine the pumps don't pump but the fish still need air. So I would think about making sure that pump or pumps have a power supply that works even if the sun isn't shining which in my opinion would be a battery control system.
Another path to take would be to get a pump that is designed to run directly from a solar panel. The problem of no sun no pump is still there but at least the pump will be matched up to the panel wattage to supply a specific gpm based on the depth or height it has to pump.Comment
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