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What do I need for a solar powered extractor fan?

  1. Sep 1, 2009 #1
    Hi there,

    I'm renting, so can't add power sockets and wires to my flat.
    My bathroom is windowless and passively vented.

    I'm going to put a solar panel on the roof and drop a wire down the chimney.
    I was thinking about getting a 7.5v 2.5w solar panel and a fan and directly connect them - that way at least during the day the air is being actively changed.

    I live in a reasonably sunny country, but would like the fan to work during the day even on cloudy days.

    My questions are:

    In order to easily mount the fan in the hole I'd like to use a PC fan, can a 7.5v 2.5w (Max) provide enough power to get the fan going?

    Would it be okay to use a 5v/6v fan or am I just going to fry it?

    What kind of fan: i.e voltage, draw etc would work with such a varying input power?

  2. jcsd
  3. Sep 1, 2009 #2


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    Normal extraction fans running off the mains would be about 50 watts.

    Their main function is to clear the fog after you have a shower. This is to avoid condensation on the walls and ceiling as this would encourage the growth of mould.

    So, they need to act quickly and then turn off. There is no point in running a fan all day.

    You might get a PC motor to run on a small solar panel, but I doubt if it would make any difference to the moisture level in the room. Even a small bathroom is hundreds of times bigger than a PC case.

    The best way would be to just open the bathroom door as soon as you finish your shower and get dressed. This would let the fog escape.
  4. Sep 2, 2009 #3

    I suppose I could elaborate a bit, the bathroom smells stale because they've not installed a U-bend on one of the pipes, I think it's the shower tray or the toilet overflow or the floor-drain - they're all embedded in the walls so often the room smells bad not because of my showering but because of this. I've pointed it out to the landlord, who doesn't speak English at all so I'm not sure he fully understood. I think if there's a bit more airflow it'll help at least reduce the smell. In the mean time I'll block/plug the bits I can an burn incense sticks.

    I was thinking that a 60mm 5v fan would help shift some of the air. Is that a total waste of time? I've not bought the panel (7.5v 2.5w = 30$) - so can save some money if you think it's a dead-end.
  5. Sep 2, 2009 #4


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    No, sorry, I don't think it would have enough power to do anything much.

    I think you have a plumbing problem rather than an electrical one.

    Which country are you in? Are you a local?

    In most countries you could claim this was a potential health problem with some justification. Bad smells probably originate from bacteria.
    The landlord isn't going to try to understand until you force him into it. If he is faced with a health inspector's inspection he might suddenly start to understand and do something about it.

    I think Dettol or similar antiseptics are available widely. Could you try diluting something like that and pouring it down the sink?

    You do need to work out which outlet it is coming from, though. Go around and sniff each one.
  6. Sep 2, 2009 #5
    I doubt I'm local, I'm in Istanbul!
    Health and Safety type things don't happen here - for example wearing a seatbelt isn't a legal requirement and until recently if you wanted a driving licence you only had to ask for one.

    I will however ask a friend to tell him in Turkish, I'm sure that'll help.
  7. Sep 2, 2009 #6


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    One place I've always wanted to go.

    Good luck with it.
  8. Sep 2, 2009 #7
    You need a decent size fan and that means quite a few Watts.

    Solar panels are usually rated at maximum output which is only achieved on bright days and only when the Sun is square on to the panel. Typical output is far less than the max. You need to store the elec in a battery.

    You will end up with 1 - 2 square metres of panels and a large battery.. Cost you a fortune.... NOT really on.
  9. Sep 7, 2009 #8
    It might be simpler than you think. Sometimes "U" bends dry out, and then the fumes enter the room. Its probably the drain in the floor, which may never get water down it normally.
    If that's the case, add water occasionally, or I guess water once, and then a small amount of oil to stop the evaporation.

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