Inquiring into Solar setup to power a few hundred watts of lighting & Ventilation 12w&60w

Discussion in 'Start here' started by BKW-III, Sep 17, 2017.

  1. Would like to power a separate structure with lighting & ventilation that doesn't/or at least lessens impact on My Grid usage.

    Total Wattage's of lighting needed will likely be under 400watts,.. and a couple small ventilation fans [12w and 60w (already have)] while only being needed for a portion of each day,.. [maybe 8-12hrs/day depending on time of year and/or Daylight Savings Time] while ventilation will generally be used continuously. [72watts total for ventilation requirements,.. the 12w is like 2 to 3 Amps and change,. the 60w though I'm not sure of amp rating].

    How many 100w Panels,.. and Batteries [and what Amperage requirements,type, etc.] would make up the best system for such a setup, while also taking into consideration, that I'm trying to do this in as least a costly manor as possible ;)

    NOTE: I'm trying to make use of, and repurpose a 2000w [4000w peak] Modified Sine Wave 12v Power Inverter [to be run off My Jeep ;)] that I bought prior to,.. for a Hurricane Outage I expected to last for a couple weeks,. [to power Fridge( 6.7 Amps), some lights, and low Amp Window Unit A/C (4.8 Amps)] and only lasted less then 24 hours LOL [got REALLY! lucky]

    I've since sparked within Me, the desire to maybe go Solar to some degree with any extra/added power needs, [as well as aforementioned outages] other then my usual day to day consumption,.. if it doesn't mean a second mortgage,.. or signing over My first born LOL ,.. hence, My Inquiry.

    I also figured doing so, may even be a much better option [and still be usable for] in Off Grid Disaster Situations mentioned,.. [since I do! happen to live in Hurricane Alley lol] given fuel shortages in those instances may be the "make or break" of the Intended backup even being viable at all much beyond a single tank of Gas.

    Any help in this regard is much appreciated.

    Signed: DIY Solar Setup Curious
    Last edited: Sep 17, 2017
  2. Also trying to talk My LandLord into investing in a Solar Backup for powering the Well Water and Septic Pump Houses/Stations that are responsible for pumping several home's Water Feed and purge. Though I need to find out the draw His Pumps have for power consumption needs first before any inquiries into that of course. That way People here will at least be able to keep water flowing until grid can be restored in Hurricane/Storm related outages that can sometimes last for several days. [Though I believe City is responsible for purge pumps, so will likely only need to power Water Feed pump]
    Last edited: Sep 17, 2017
  3. Tuicemen

    Tuicemen Solar Guru

  4. Thanks so much for the prompt reply.

    With provided link,.. I figured I'd need somewhere in the neighborhood of 12 100w Panels,.. but still trying to figure out how many of what Amperage Batteries would be needed for such a setup for off light hours operation. Since it's mainly the ventilation [low draw] that will be operating 24/7,.. and Lighting will only be needed approx. 10-12 hours a day. of which at least 4-6 solid hours hours of direct sun will be offsetting drain rate to some degree. [on clear days] ...

    So far I figure I'd need at least 8-100Ah [or less in higher Ah Batteries] Batteries to fully power 1 day off grid,.. of a roughly 4750Wh./day draw. [@50% drain, 400Ah x2=800Ah]

    JEEZE LOUIS! lol That's $1400 to $2000 on Batteries alone for quality Deep Cycle Batteries,.. then God forbid,.. more then one day is needed,.. and it happens to be too cloudy to recharge. lol [16 Batteries? lol] w/12 Panels @roughly $100/ea,.. a Charge Controller,.. cables, mounts,.. [and considerations of where to place them,. while factoring in ventilation, Ambient Temps if needing to be outside [In Florida] etc. and sealed decent Bank Box to fair the weather in such case] It seems like I'm looking at roughly $3000 [less expensive battery setup] to $3800+ [for premium battery setup w/ outdoor bank box] just to run a few hundred watts of lights and a couple fans,. SOME of the time.

    I think I'll just go back to planning on running the Inverter off the Jeep in those rare occasions a storm knocks the grid out,.. AND,.. eat any extra grid costs of operating the rest of the time,.. which isn't but another $20 - $30/month above what I pay when not running the above aforementioned items. Even if I have to go through 6 tanks of gas [baring any shortages] on extended outages w/Inverter,.. it will still be much cheaper then going the Solar route I'm very sad to say.

    As much as I'd love to be able to cut My dependency on the Utility Company,.. It's just not cost effective. The Batteries would be past their life cycle and in need of replacement well before initial investment even started paying for itself,. and BAM!,.. another $1400 to $2000 in Batteries. [IF! the price for Lead,.. and therefor Batteries, hasn't skyrocketed by then given Environmental Concerns (And $$$ grubbing Regulatory Agencies) of the day]

    Then You have Cell degradation over the same time period, lessening their efficiency until they too! need replaced, or extra panels/batteries are needed to offset efficiency loss.

    And all simply to retask, and get more use out of a 2000w Inverter I paid $140 for that will rarely be needed otherwise, but a couple/few days a year. [My initial reason for asking, but really liked the idea of going off grid with at least some of My power needs,.. so the wheels started turning LOL ;)]

    Seems a never ending cycle and guaranteed Money Pit. I just can't justify the expense at this time.

    Oh well,.. it was fun to dream while it lasted. lol ,... Thanks again for the quick reply :)
    Last edited: Sep 17, 2017
  5. Tuicemen

    Tuicemen Solar Guru

    Initial outlay can be a hit to the pocket book. That's why many like myself choose to slowly expand.
    Good quality solar panels will last well over 25 years so chances of you needing to replace those are slim.
    Batteries have a life expectancy of 8-10 years and the bank should not be added to(expanded) mixing new with old.
    Many good inverters even modified sine wave ones have a charger built in if yours does you could use the grid to charge the batteries if panels don't produce enough.

    Using your estimated initial cost and your monthly cost of running off the grid the system will have paid for itself in 10 years, sooner if grid prices go up (which everyone knows, they will)
    Prices on panels continue dropped and out puts continue to rise. What I paid for my first 75 watt shell panel will today buy 3 230 watt off grid tie panels
    As well Batteries continue to improve. My first bank consisted of 10 6volt batteries at 240 ah each after 12 years I replaced them with 12 6volt a 320 ah cost was roughly the same per battery.
    My original batteries are still in use at my hunt camp today however the system doesn't get the work out it use to.
  6. What ever you figure out your batteries to be, multiply times 2.5 so 20 x 100 Ah batteries is closer to what you need if your daily usage is correct. (knowing exactly what the total usage is going to be helps, also look into what you can do to make your total usage lower. For example think of using something like RV LED's for the lighting, and Fantastic fans or some thing that is similar. you use a lot less power if you do not have to invert before using.) Go smaller on the solar panels at first start off with 5 or 6 panels at 100 watts, it is much easier to add more solar over time, but adding more batteries at a later time is not good for the system even if they are the same exact batteries (more so if they are lead acid). Solar panels on the other hand you can add them one at a time if you like. Also watch out in Florida, some counties in FL do not allow a building to be completely off grid. (not sure if you can get away with sending a grid power line over just to charge the batteries on bad days counts or not, but at first might still be a good Idea to have such a connection.) Also no matter how small of a solar setup go with a good MPPT Charge controller, that way you can expand in the future and get the most out of the panels you buy up front. As for the price of batteries look in to all types of batteries, I got a great deal on Li-Po batteries when I was setting up. and they last longer and can DOD a bit deeper as well. I have 12 LED's, 2 fantastic fans, and a 500 Watt inverter for a TV that I can run all night in my RV using 318 Ah of Li-Po batteries. and still have enough to do it all again a second night. (though that is cutting it close, for me 500 Ah would have been just right and I'll be making that change when I have to change the batteries.)

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