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I've got a 20 watt solar panel laying around and I picked up a water pump for making a fountain. The pump is rated 12vdc and the panel is putting out 18v. I did a quick test to see if the pump would work right off the panel, and it did. But can this be done long term? Or should I use a requlator or something to bring the voltage down. Also what happens when panel is not putting out nough power? any damage?
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It all depends on the DC motor electrical rating on the pump. They should be able to handle voltages above 12vdc but maybe not as high as what the panel can put out. Also if the panel is not producing enough "current" the pump will either slow down or stop.
I have a couple of roof vent fans that use 10 watt solar panels. The fans will run at various speeds depending on how much the sun is shining at the time. The DC motors on the fans were designed to run directly off a solar panel but your water pump might not be designed like that.
If your pump requires a consistent power source to run properly then you will need a battery and charger with that 20 watt panel to make it work. -
I don't think that pump motor will ever reach 18V with a 20W panel.
When the motor is not getting enough Voltage to start it will squeal, I had a similar problem with extractor fans and solved it like this.DemComment
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I checked the panel again............
.and I am getting a reading 20v-18v depending on the panel orientation. I hooked up a pump I have (12v) and it is pumping off the panel as we speak, and I figure I'd run it today to see if it makes it. I'd imagine it would fail sooner rather than later, later being in a few days. Otherwise it should last 10,000 hrs as advertised......I'd be happy with half of that.
Question: If my panel is putting out 20 watts, and all I have is the pump attached that takes 5 watts, am I correct that the pump will use what it needs for power and the excess power does not really exist since there is no where for it to go?Comment
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Yes, your panel is capable of putting out 20 watts under the right circumstances and with the right load.
The light energy it does not convert to electrical energy just gets converted to heat in the panel.
Same thing that already happens to ~80% of the incident light energy.SunnyBoy 3000 US, 18 BP Solar 175B panels.Comment
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As long as you are ok with your fountain pump stopping whenever there is cloud cover, then it will be ok.
The longevity of the pump motor depends on its quality and design.
Then there is the option of using a Linear Boost Converter (sp?)...[CENTER]SunLight @ Night[/CENTER]Comment
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