Pv compost airation.. hence in the weeds :-)

hi, i am building a ‘compostgenerator’ room with pipes to aerate the material.
in order to get air into the pipes i endeavour using a 12V fan which is directly connected to a smallish pv to drive it as the sun shines. any ideas if this is possible?
any tips here would be welcome
God bless

Need a few estimates of the size you looking at and does it need pressure or just air flow, also run time.

Those camping mattress blowers use 12v but you will go deaf if it runs all day and not sure how long it will last or if its enough air flow.

hi @Whatyamacallit , thanks for responding. i think a 12v pc fan will do the trick as pressure is not my aim, rather constant airflow - pc fans are reasonably cheap and run for years, i have two [smallish ones] on my 6 years old axpert inverter who have been sucking air out of it for 4 years

May I suggest that a better plan is to agitate the compost?
What is the compost to be used for??

thanks @Richard_Mackay , i’m about 70 and although that would be good exercise i’d prefer to have the sun do the job for me - its ordinary compost, garden and tree cutoffs/wood chips etc with a handful of hi nitrogen fertilizer and some water every now and then… nothing special
i had plans for a 200l container with internal fins on an axle driven by a small motor with pv energy but i anticipate a compost chamber/room - i’ll attach a sketch…

I think this has a passive solution.
Composting generates energy (heat).
Use that, why add more energy?
Sink a 150mm black PVC pipe drilled with holes on the lower half into the compost heap.
Let it stick out the top of the heap by 2m.
It will draw like a chimney (I think).
The air escaping will have to be replaced by fresh air drawn into the compost from all sides.
This may not be the eventual solution, but I’d still persevere looking for a passive solution.
In fact, I think a bit of YouTubing and you made find one, I don’t think your problem is unique.

tx @Phil.g00 , you are right, my idea is as old as compost itself hehehe - yet i’d like to put a pv in direct circuit wit a 12v fan to achive a low airflow via pipes underneath the stuff - so the basic question remains if that can be done

Can yes. There is always a way.

Those 12V DC fans from PCs can run very well and very long. And they are cheap to buy and replace. You will need to make a small housing to convert the square shape into a round pipe. If you look into a piece drain pipes or gutter pipe, they have fittings down to any size so you can cheaply get to the size of pipe you want to use. The reduction will also give you more air speed in the smaller pipe.

It will work best of you have a piece of the large pipe before and after the fan. Largest piece after the fan will give you a bit of a compression chamber before the reduction. 10cm-20cm on each side will work fine. You could also put more that one fan in serie in the pipe if you see you need more presure.

You could also look into heating the pvc pipe with a heatgun, which makes the pvc soft and quite compliant. It would not take much heat to allow you to shape the pvc from round to square. Might need a jig to spread the round pipe out to square.

I have in the past pressed square channels into 110mm pvc pipe with a wooden jig I made up.

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tx @Louisvdw and @Deon_in_ZA , those are good ideas, i was looking at a 90 degree section drainpipe to put one or two fans in with a reduction to 40mm pvc with a piece of mesh on the downward piece to keep goggas and rain out, the reduction will increase air speed and hence pressure in the sections under the compost. what size pv would you guys suggest? i’ll obviously mount that on top with a slight north angle

You might need to do some tests. It would depend on how much meterial and it’s density would be on top. Die easiest would be to use 40mm or 50mm PVC pipe. Make a loop. That way the peasure will be more evenly

A bit of YouTubing:

And the results 1 year later:

…Make a loop. That way the peasure will be more evenly… good one to remember @Louisvdw !
in the meantime i have sourced a cheap 12V 10W solar panel from acdc which i will connect straight to the fan/s; now for putting it all together, i’ll post the finished project snap :slight_smile: