Solar Attic Fan Mods

System
System Posts: 2,511 admin
in General Solar Power Topics #1
Hello out there. I tried first searching the forums for what I'm looking for but didn't find it. I hope I'm not being repetitive.

I am contemplating installing a solar powered gable fan in our attic to reduce the temp/humidity buildup there. The two ready-made units I am considering (Air Vent NPSG8 and Solar Star Conversion Kit) may require a modification to the design to be more efficient - it seems that the supplied panels (at least for the Air Vent unit) require direct sunlight, otherwise the fan doesn't spin.

I would like to replace the supplied original panel with an ambient light panel. Unfortunately, both manufacturers utilize a 10 watt 24 volt system, thus a simple panel switch won't work.

Can anyone here suggest a cost-effective way to use an ambient light panel (or two) to provide the 24 volts necessary? Since the cost of the Air Vent is over $200 and the Solar Star is closer to $400, might it be more cost effective just to buy a $50 A/C fan and create a mini solar storage/inverter system?

Thanks in advance for any help and insights!
MJA
· Share on Twitter

Comments

  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #2
    Re: Solar Attic Fan Mods

    solar only works with direct sunlight, no sunlight, no power

    Its much more cost effective you just install passive vents or a turbine type ( spinning rotor )

    Also having powered venting ( AC usally ) can cause negative pressure in the attic which in turns pulls air from the building actually making things worse than no fan at all, so take care in what your doing
    · Share on Twitter
  • Telco
    Telco Solar Expert Posts: 201 ✭✭✭✭✭
    #3
    Re: Solar Attic Fan Mods

    On my last owned house I installed a powered attic fan into the ceiling directly, close to the top. It would draw air in each side of the house through the vents put in when the house was built and draw it out the middle. Worked great, made a nice difference in house comfort and my summer cooling bill. No need to worry about sucking conditioned air out so long as you have more opening airflow than you have being drawn out. The turbine fan I replaced with the powered one made a huge difference in attic temps, and in my power bill. Unfortunately it's been so long since I put that unit in (sold the house over a decade ago) that I don't remember anything about it anymore.

    Current house has many vents on the top so you'd think it would be cooler than it is, especially with the attic access door being left open and the garage door cracked, but it gets to be 20 degrees or better up there. With the attic access closed it gets even hotter, and the house has eave vents all the way around along with the vents along the top of the roof. The only thing stopping me from putting in a powered vent is I don't plan to be there much longer, and see no reason to risk falling off the roof for a place I'm planning to sell soon.

    That was something I neglected to mention, my attic fan was NOT solar driven but was thermostat controlled. Very nice, strong, quiet motor on it though. It was a lot like this one, may even be the same one. I wasn't able to find a power consumption chart anywhere, but it looks like this is the manufacturer site so if you really wanted to you could email them and ask them what the power requirement is, then figure out what you'd need to run it off solar. Most likely need 10 amps at 120V though.
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Re: Solar Attic Fan Mods

    Here is another attic fan thread that includes lots of information and pointers to other threads...

    Short answer--as SG said--full sun for solar panels is the only way the panels work--solar attic fans are pretty much a waste of money--expensive and the motors generally do not last long... Passive venting (both inlet and outlets) will be a much better way to go...

    You can also add grid-tied solar system to your roof--the shade from the panels really reduced my attic temperature--of course, $20-$30,000 to keep your attic cool may not be the only reason for such an investment. :p

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • System2
    System2 Posts: 6,290 admin
    #5
    Re: Solar Attic Fan Mods

    Thanks very much for the responses and the valuable info!

    We do currently have passive vents in place - roughly 15" x 20" vents in each end. In spite of this, the temp in the attic still gets pretty high during the summer. Maybe I'm just expecting more than I should. I had considered a turbine-type vent, but I'd prefer not cut a hole in my roof if I can avoid it; and, simply put, I don't do so well on a roof (or a ladder, or a tree...).

    Solar Guppy and BB.: If I understand you, the advertisements I have seen for 'low-light' solar panels (mats) are inaccurate? That is good to know - thanks!

    I guess the bottom line is that if I do decide to install a powered vent, I need to be certain that the exhaust doesn't exceed the intake. I know that I have heard from other sources that the passive turbine vents can make a significant difference - maybe the solution is simply to pay for a professional installation - or have a hypnotist 'fix' my problem with heights.

    Thanks again for the info and insights!
    MJA
    · Share on Twitter

Categories