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Post by chris877773 on Aug 13, 2012 9:12:43 GMT -5
I ause m new on ere
I have just done sort of a conversion on the back of the house with a glass roof , as i had to raise floor levels ect i put a under floor heating pipe in (10mm x 25m long )
I want to use solar to heat the floor so I am putting a black radiator on the wall under the glass roof and useing a 12v pump
My question is the pump is 6.6w how big will the solar PV panal need to be to power it
Any help welcome with my mad (cheap) solar project
chris
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Post by caveman on Aug 13, 2012 14:46:36 GMT -5
Hello Chris,
Welcome to the forum.
Are you planning to run the pump directly from the solar panel? Pumps usually draw an inrush of current when they start. The panel must be able to supply this current which can be many times the running current so you would have to install a higher wattage (and price) panel than would be required to supply 6.5watts. Also, when the panel is producing power but not enough to start the pump the current is running through the pump windings, heating them which is not good practice. If you use some electronics and a re-chargeable battery between the panel and the pump this all gets easier.
conor
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Post by chris on Aug 14, 2012 3:00:12 GMT -5
AAA I see
I dident want the complication ov a controler , battery ect
I would prefer sun shines pump runs , simplz
I have to make my own panals as they need to fit in the eves under the glass so i will over rate the solar pv as much as possible but that still means in low light I could still get the windings problem
the pump is a brushless type so will that make a difference
do the internal electronics only start with enough current ?
last problem is filling and expantion in the system
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Post by cye on Aug 14, 2012 13:07:28 GMT -5
chris, if it's the little brown pump you have, then these are not specifically designed for running directly off solar, but i have successfully run one of these from a 10w pv panel and the pump starts working when the panel manages to deliver 8.5v across the pump. the brown pump is specc'd for operating 9v-14v.
there are other 12v pumps which are designed specifically to run directly off pv which have clever circuitry to avoid the problems caveman refers to and which are able to extract the most from the pv panel in varying light conditions.
if you are stikcing with your 6.6w pump i would still recommend running from a large car battery and use your pv to top the battery up, but then you'll need a pump controller which you can build yourself for less than £10 if you can solder.
all the best
cye
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Post by chris on Sept 18, 2012 2:03:10 GMT -5
well upto now I have installed all the parts and have to make the solar panals , got 36 6x3 cells , haven not worked all the numbers out yet so we will see !!!
as a backup plan could all ways just use it on mains power and use a under floor heating controler
The black radiator def works thow !! it gets quite warm even thow the wether rubbish
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Post by caveman on Sept 18, 2012 4:55:35 GMT -5
Brilliant! Any chance of a few pics! Also be sure to use a safe anti-freeze as we approach the winter.
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Post by chris877773 on Sept 18, 2012 7:13:50 GMT -5
been waiting in for the new cooker .... so thinks I , time to practice soldering  iron gets too hot and breaks the solar cell , how do i post photos caveman ? |
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Post by caveman on Sept 18, 2012 12:26:39 GMT -5
Chris,
Save a copy of the photos in lowish quality so as to keep the file size small and then 'browse' in the attachments section of 'post a reply'. Find them in 'My pictures' or where ever you saved them and then press attach. That should do the trick.
c
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