Why cant i ?



  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Why cant i ?
    Derik wrote: »
    The other thing is that it's a weekend cabin so if you use all your power on Sat, and Sunday you have all week for the batteries to re charge so who cares.. if you use more than what you make for two days.

    That is the formula for premature battery death.

    I wouldn't make such generalized statements about power usage either; what you are comfortable with and what other people feel they need can be quite different. My system is adequate - unless the kids show up.

    As always the process is: How much power do you need? This is how you get it.
  • DerikDerik Solar Expert Posts: 82 ✭✭✭✭
    Re: Why cant i ?

    I thought the original poster was pretty clear on what he wanted to run, and also made it clear it was a weekend cabin.

    Being a weekend cabin he doesn't need to worry about a few cloudy days he can pretty much expect his batteries to be fully charged during the week. I have been to Southern Colorado and it's ideal for solar.

    My batteries are still going strong, going on 6 years now on my "weekend" cabin. Why should he copy what's required or needed up north? If I had posted my needs here 6 years ago and listened to the far north guys what would I be stuck with? My 65 watts is still going strong with 2 T-105s showing no signs of age.
    The only thing he wants to run that I didn't have was a ceiling fan.
    I even vacumed my cabin and charged all my power tools, and phone. Never used all the power available or ran my batteries to less than 12 volts.

    Don't mean to offend anyone but my real life experience is that my solar for both my cabin and house makes way more than what I expected and I don't see any of the losses that are common up north.
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: Why cant i ?

    No offense taken.

    I started out with 65 watts and a pair of t-105s powering a radio and a couple of reading lights, and that system is still going strong 12 years on,, but (and that is a big but) it sees and has seen very little use.

    Design "backwards" from the loads if at all possible. Loads determine all other calcs and components. Define the loads, and you define the components.

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Why cant i ?


    Just because I live in the frozen North doesn't mean everyone does. :p

    When we give generalized information about system design it is that: generalized. This includes the "standards" and "typical" data, even if those caveats are not always included in the text. It's to give people an idea of what to expect so they can come up with "ballpark" figures.

    Almost inevitably the value of the PV Watts program comes in to play, because as I've said innumerable times solar installs are highly site specific. Sometimes posters do not follow through and get information about their particular install. I suppose we should warn more about that, as it is not always the happy scenario of living further South and higher up the mountain no place near the city (great improvement in harvest potential).

    So we're stuck with giving the basic info, because people are less likely to come up short on power if they follow that than if they try to depend on a best-case scenario. Almost invariably we find people over-estimate their power production and under-estimate their usage. Which would you rather have? A system that has extra capacity for cloudy days or one that requires you to turn the lights off at 7:00 PM or else have the 'frige shut down at 2:00 AM?

    If you get the margins for error all slanted in the right direction you'll be happy. If you don't ... :cry:
  • DerikDerik Solar Expert Posts: 82 ✭✭✭✭
    Re: Why cant i ?

    I guess everyone is a bit different but power in a cabin to me is a luxury not a necessity. I am ok if I have to conserve a few days a year. I would rather do that than have a system that makes 3 times what I would normally use. I have both, my cabin just produces what I would use and my house makes 3-4 times what I would use.

    For a weekend cabin money to me is more important than power and if I have to shut the lights off at 7:00 pm a few times a year I am much happier than having all this reserve power that I only use once or twice a year.

    I would rather eat steak in the dark than eat hamburger in the light! Plus a cabin should have lanterns, and a fire place.

    I think a "weekend" cabin has a different formula than a house you live in 24/7 plus the southern factor is huge. It may be another "generalization" but it seems to me most of the posters who see all the losses and recommend more solar or more generators or more batteries are north of the Mason Dixon line.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Why cant i ?


    For years ours was a weekend cabin with absolutely no electricity save some batteries in flashlights - which were usually dead whenever you wanted them!

    As years went by and we wanted to spend more time there electricity became more of a necessity than a luxury, as it is a very efficient way to do certain things. Hauling water from the lake in buckets is fine for a couple of days now and then. Doing it every day gets tiresome fast, especially as none of us has found the secret to growing younger.

    So from nil power to a panel to keep the radio phone charged (just in case) to pumping water with a gen to running the computer so we could work while on vacation (tell me that isn't crazy!) to living there May through November ... it's a familiar saying around here; your loads grow with time.

    Since most of the time we see people post here with too little panel for the amount of battery or just plain too small a system for what they want to do, advising people to try and scrape 2 kW hours a day out of 200 Watts of panel isn't going to happen. And remember; your southern latitude isn't a solar panel's best friend either, as they don't like the heat (if you're up the mountain this isn't so much of a problem).

    Besides which, is not the first thing we tell people about going off grid "conservation, conservation, conservation"? :D
  • DerikDerik Solar Expert Posts: 82 ✭✭✭✭
    Re: Why cant i ?

    Right on, I got you and totally agree.. it's all about conservation and power does make our lives easier. Recently my Dad and his girlfriend were at my new house and seemed to be oblivious to conservation, running or trying to run everything in the house at once. They have inexpensive power in Oregon and don't really care about power use.

    Nothing teaches conservation better than a small system or living on grid in CA and having to pay obnoxious power bills.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Why cant i ?
    In general AC induction motors are quite inefficient when operated at reduced speed, compared to PM rotor 3 phase inverter controlled motors, or brushless DC motors. Most, especially the cheaper fans have cheap induction motors which can be fine in many cases, but when every watt counts - - - - not so much.

    I've got two 10" camping fans retro-mounted into a 'duallie' and hard-wired to my battery. Their combined flow feels about the same as a standard box-fan on 'Low'.
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