NEW AND NEED HELP PLEASE

XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
I am.new to the solar world and wanted to start small I have a 35 watt panel and a 70 watt on the way I have a fan that says 80 watts 12v a small battery 12v 15AH and a cheap charge controller what I want to do is use the fan as a attic gable fan run it off solar during the day and for a hour or so after the sun goes down on battery the manufacturer told me the controller will.not do it and to get a timer I want to do this to help cool off my attic/bedroom to lower the a.c. bill and learn as to broaden into other areas please can some one help me thanks

Comments

  • PhotowhitPhotowhit Solar Expert Posts: 4,769 ✭✭✭✭
    Well them math doesn't really work.

    Is the fan a 12 volt DC fan? 80 watts is pretty large fan, but perhaps a large radiator fan from a vehicle.

    There is a lot of losses in the system, first solar panels are rated at Standard Test Condition (STC) but when they are actually allowed to heat up they typically produce about 75% of the panel rating. Hence a rated 105 watts will likely produce 79 watts.

    If the fan is running during the day, there's no energy to charge the battery.

    Solar panel only produce well with direct sun. So nearer dusk, they likely will be producing very little unless point to the setting sun. With a fixed solar panel and a sunny  day, normal best case you can manage about the equivalent of 6 1/2 - 7 hours charging. Of course some of this will be less than the best the solar panel can do because the sun is at a glancing angle to the panel.

    If your fan is a DC fan, it might well run off the panels directly, and this without the charge controller and battery might be the best use. It's something you  can wire up and test out. There are other attic fans that work in this manner. In general there is a range of acceptable working voltage and amperage range...

    I have an attic fan that is made to run directly off a solar panel. I believe the fan is actually considered a 24 volt fan, 12 volt nominal panels typically produce 17.5 - 20 volts.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    The fan is dc yes I bought it on Amazon it's a amtrak solar attic fan 40 watt with 12" fan is the listing its a black plastic fan with a solar panel the seller sent me a 35 watt panel instead of a 40 watt panel and because of the mistake he gave me a deal on a 70 watt panel as well but assured me the panel is 40 watts but labeled wrong i do not know i will be getting the 70 watt panel tomorrow. the fan runs on just the panel that i have now not super fast like when i hook it up to the charge controller and battery but still runs the attic is my bed room the walls were made vertical and i have a space to access i want to mount the fan in there cutting a hole in the roof and covering it with a static roof vent to stop rain and such from coming in when i was looking i saw one that was a whole unit prebuilt that had the fan panel back up battery and you just put it on the roof i could not afford it so i made due also it has a low cfm (cubic feet per minute) and am just trying to add a back up battery to help disipate the remaining heat after the sun goes down. again i am new to all of this but i also have another fan that is an inline duct fan 6" it is ac though not dc which means i would have to get an inverter it runs on 37 volts it says would that be a better option? also i have a timer that i use for lights around my house just a small analog one i added it to the set up today from the controller load to the timer to the fan and it did not work i thought it would act as the switch and cut the current to the fan when the timer went off i will add some diagrams to what i have
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    will this work that is on the diagram? the splice should split the load power to power both the fan and the battery i would think at least
  • BB.BB. Super Moderators, Administrators Posts: 28,186 admin
    Why did the first drawing not work?

    The second drawing could work (I guess), but there is a risk of the solar panel charging the battery bank directly (bypassing the charge controller) if the timer was on when the sun is up.

    I am not a fan of doing things where if something goes wrong, other things can go wrong too.

    -Bill


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    I do not know why the first did not work it is a analog timer from Wal-Mart that u plug into the wall and pop out little prongs for on and off

    As for the second if there is 2 lines running off the panel one directly to the fan it should only take the power needed or split to the controller to charge the battery which is what I want then the timer would switch on at a designated time releasing the battery power to a designated time when it switches off that's what I want to do have the fan run on solar and charge the battery for later

    I realize I need a bigger battery and will get one just do t want to spend more money with put understanding everything first
    I just hooked up the panel and fan directly I was getting 20.1 v on my meter with out the fan and with the fan 5.8 v is the fan using only 15 v roughly and the remaining 5 v just hanging out? If so I know I need more power 13.4 v to charge my battery how can I direct the remaining to the battery for charge then out of the battery when the sun goes down
  • westbranchwestbranch Solar Expert Posts: 5,114 ✭✭✭✭
    What does the battery get when the Charge controller is between the PV panel and the battery? it should be in the 13.5 to 14.4 volts range unless the battery is fully charged. The 21 V you saw when not using the Charge controller is called the Open Circuit Voltage and you do not want to send that to the battery more than a few seconds or you will damage the battery...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    I put the battery on a charger and charged it over night so it is full
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    This is everything I have right now I have the other panel coming tomorrow that is supposed to be 70 v how can i find if the specs are right the guy I got this panel.from assured me it was 40 even though it says 35 I want to see if he is telling me the truth and if the panel coming tomorrow is really 70 if so between the 2 I would have 105 or 110
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    I also live in ohio if needed to know
  • westbranchwestbranch Solar Expert Posts: 5,114 ✭✭✭✭
    PLEASE use some ....... periods....... when typing. run on statements are hard to decipher what you are actually saying..
    you said  on my meter with out the fan and with the fan 5.8 v is the fan using only 15 v roughly and the remaining 5 v just hanging out?

    I am no expert on this but I think what you are seeing is the fan puling down the PV Voltage to 5.8 Volts. you should be connecting the PV panel to the Charge controller to the Battery and then the Fan to the Battery.  
    Then read the PV voltage going into the Charge Controller.
    Then read the Battery Voltage and the voltage going into the Fan...

    You should see ~21 V at the panel and IN to the CC ... and~ 14 V+- at the CC out and battery, maybe higher as with the fan ON it may draw more than the CC is sending to the Batt and Fan. Not knowing the fan specs etc...

    There are a bunch of safety issues/items you need too.Circuit  Breakers or suitable fuses, a combiner box maybe, depends on the next panel, buss bars to connect to battery terminals, water resistant entry through the roof etc... 
    hope this helps.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    I am sorry about the run on sentences I am using my phone. But what i said is how I ment it my meter with out the fan attached is reading 20.1 but when I attach the fan it drops to 5 or so. When I attach the CC it charges the battery at 13.4 but it is drawing more then the amount taking in cause it's killing the battery it's a cheap $15 CC from Amazon the fan specs all I know is it says 12v 80 watt on it
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    If you look on Amazon for amtek solar gable vent fan 40 watt that is what I have. It is supposed to be plug and play which I figured would be good to start and learn as it can be upgraded. I have no idea about fuses and all and will get a weather box before I install it, right now it is just in my garage and I'm doing a dry test run and getting it right before I cut a 12 Inch hole in my roof lol
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    The other panel is supposed to be 70 watts how should I connect them series? I was thinking another option using the 35w to power the fan directly then the 70w run thru the controller 70w should be more then enough to charge the battery and run the fan with the remaining power right? And for the fan I don't understand it says 12v 80w is that max? If so why from the panel is it only pulling the 15 instead of the whole 21 I'm lost
  • EstragonEstragon Registered Users Posts: 3,043 ✭✭✭✭✭
    Think of the battery as ballast. It will stabilize voltage, and absorb some the variable current required by the fan. For example, the fan may take a lot of power to start turning, and less once it's going. The panels have no ballast, so the fan sucks the voltage down too far.

    You need the panel and controller to properly charge the battery. Post the specs on the two panels (esp. Imp and Vmp). Odds are they're both 12v nominal panels with Vmp ~18v. If you put them in parallel (+ive to +ive), you'll get ~18v and maybe 3-4a charging current in full sun - likely enough to charge the battery if you can aim the panels about perpendicular to the sun.


    If the fan takes 80w, that's ~7a. Quite a lot for a 15ah battery. If it continues to take 7a, and the panels can only produce 3-4a, the battery will obviously get run down. If it only takes a couple amps to keep running, the panels can keep the battery full as long as they have sun.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    Should I just go ahead and return everything because I feel lost. If I were to return everything could someone recommend a starter system that I could learn from I have seen the Harbor freight 100 W kit any thoughts or suggestions
  • EstragonEstragon Registered Users Posts: 3,043 ✭✭✭✭✭
    If you want to learn from the system, carry on. What is making you feel lost?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    Just not understanding any of it when I bought the panel it was supposed to be 40 watt the info says it's a 35 the guy assured me it's a 40 I don't even know if that is a 40 or a 35 the fan says 12v 80w does that men 80w max? The CC led me to believe that the solar power would pass thru the CC allowing solar to power the fan until night then it would draw from battery and it doesn't I try a timer and it didn't work I just don't know where to begin. Then the conversion and math no understanding of it but I am good at math just all of it in th3 pics i posted contains all the info I have on the panel fan and CC and I feel like I wasted money i don't have.the purpose of this was to help get rid of the heat in my attic/bed room to better cool it and save money on the a.c. but honestly with the money I have spent I could have bought the prebuilt unit for just a little more
  • mike95490mike95490 Solar Expert Posts: 8,033 ✭✭✭✭
    I would expect a wallmart timer to be a 120VAC timer, and would smoke in a minute on DC

    I would try the simple solar panel and fan, and see if after a week you need to add the complexity of a battery and charge controller.
    Know that adding a battery, you will need a larger panel, since it will be running the fan AND recharging the battery at the same time.

    Here's a suggestion for a PWM charge controller, that has a timer built in, that will allow Lights (or a small fan) to run for a preset number of hours after sunset.  https://www.morningstarcorp.com/products/productssunsaver-gen-3/ 
    Pick a model that has a LOAD output that can handle your fan, going larger would not hurt.  They also have a MPPT version too.




    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.BB. Super Moderators, Administrators Posts: 28,186 admin
    In practice, solar power roof fans do not really move that much more air than simply placing more openings in the roof (both high and low).

    One person here years ago found that installing new solar roof fans cooled his attic... Then a few years later noticed that the fans had failed but the attic was still cool. More/sufficient natural ventilation was what was needed.

    http://forum.solar-electric.com/discussion/621/limited-use-daytime-only-system/p1

    Just putting a new gable opening may not be enough (solar fan or no solar fan)... You probably need some more screened openings down low too. Putting fans in the attic can start drawing air through the ceiling (and conditioned air) and pull outside humid air into your home (if that is your climate) and start causing mold elsewhere in the home.

    https://www.energyvanguard.com/blog/38676/Don-t-Let-Your-Attic-Suck-Power-Attic-Ventilators-Are-a-Bad-Idea
    https://www.energyvanguard.com/blog/75600/The-1-Reason-Power-Attic-Ventilators-Don-t-Help

    I am not a big fan of solar ventilators... From what little I have seen, they only have a life of ~2-7 years or so, then need to be replaced (and usually they are not cheap).

    Here is another old thread:

    http://forum.solar-electric.com/discussion/1369/solar-attic-fan-worth-it

    A 20-40 Watt solar powered fan is just not going to compare with the volume (and back pressure) of air that a 300 Watt AC fan can move. I highly suggest doing other stuff (more soffit/roof venting), possibly adding radiant insulation to backside of roof, etc...

    Whole house fans (draw evening/night cool air through whole home and exhaust)--Is a different discussion (vs attic fans/ventilation).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    Here is the new 70 watt panel and specs
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    This is the new 70 watt panel and specs. I also got a inverter a cheap one and it's not working with the panel as the 1 panel puts out 20.1 v and it's max is 12v
  • EstragonEstragon Registered Users Posts: 3,043 ✭✭✭✭✭
    An inverter needs to run off a battery.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • littleharbor2littleharbor2 Solar Expert Posts: 1,113 ✭✭✭✭
    12 volt Inverters connect to a 12 volt battery, not a solar panel. The solar panels connect to a charge controller which then connects to the battery.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    I saw a you th e video where the guy by passed the controller it was just a thought. The whole point of this is to help cool my up stairs cause there is no return but I have 2 supply vents, I have a in line fan that is 37 volts that I put in one of the supply vent to push more air up and thought rather then the attic vent to try this.i can return the inverter, duct work would cost about 2000 which I just don't have right now. But if I hooked up the CC battery inverter panel and the other fan would the panel be enough to charge the battery and power the fan? All I know right now is that the vent fan is 37 volts
  • XGX13XGXXGX13XGX Registered Users Posts: 16 ✭✭
    You tube *
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