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Power mini pump from solar panel


New Member
Hi, I have a spa at home and made a solar heater with black tubing. I want to put a mini pump inline and hook direct to a solar panel i picked up cheap. I dont want to use a battery and eliminate buying a regulator for it.
Basically the idea is when their is sun it will heat the water in the pipe, also power the solar panel and make the pump run, when no sun ho heat, no power.
Could someone please point me in the direction for a circuit to run the pump.
Here are the specs.

12v Mini diaphragm pump

Solar panel
Pmp 190w
imp 5,34a
vmp 35.61v
isc 5.52a
voc 44.28v

Thanks in advance :)


Well-Known Member
Yes a Buck converter which converts 35v to 12v at 5A.
There may well be offthe shelf versions.
Sometimes its called a "stepdown" converter.

..You can find them on farnell, digikey, mouser, etc

Unless you want to design your own, in which case there are some good Buck PWM controllers out there.
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New Member
Hi Flyback. thanks for the reply.
So turns out i have 2 of these which i think are buck step downs. Not sure on input / amp as i googles this one and lots of different ones but all look the same lol
There isnt any markings on this either.
here are the photos.
Not sure if i can run 2 together to give higher ampage and if so how.
Any help would be appreciated :) thanks105580324_352445075734827_3823253889813229869_n.jpg


Well-Known Member
If the part number is "LM2576HV" than youre in with a chance yes. (p/n on the big black 5 pin chip)
If its just the LM2576 then its not got high enough voltage rating.

..Also, it needs to be the 12v part, or the adjustable part...what is the complete part number?

Its actually a bit naughty putting single power supplies in parallel……..the LM2576HV is 3A rated, so your two in parallel will be 6A total…however, we need to read the LM2576 datasheet to see at what current the overload protection kicks in (if at all)…because one of them will try and deliver more current than the other….and if it keeps tripping out on overload protection, ,then we’re stuffed.

If those pots are for adjusting the vout...then you can actually twiddle it so that they both deliver almost the same current

YOu can get some sense resistors and check what the current coming out of each one is....then twiddle till theyre almost equal

Also, another way to encourage them to share the current, is to put a 1W, 33milliohm resistor in series with the output of each Buck module....so there you go...you can also use these resistors to check the current........whilst twiddling.

(This of course is all based on me assuming that that chip is an LM2576HV...i cant see it, and just guessing)

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Well-Known Member
Im in the process of buying our first house, and it has solar panels. I'm very excited to see how much money it's going to save us!
This will be hard to quantify as a new owner. You would need to know what your average utility usage is with and without the solar panels. You can disconnect the solar panels and check your utility bills over a long period. Then the same with the solar panels. Unfortunately there ars a lot variation in solar output over any given period. The previous owner might be able to tell you. But they are selling the house with the solar panels as a big positive.

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