12 volt only mountain caibn in Mexico

Hi everyone, We built a 2 story hexagonal cabin in the mountains of Veracruz state here in Mexico. We use rain collection system with the large tank just up under the roofline so we need no pumps. We have 150 watt solar electric panels with a 20 amp simple regulator and 2 marine batteries. I am trying to NOT use an inverter, so everything in the house is 12 volt stuff, either bought from camper centers in the USA or here. Some incandesant 12 volt bulbs, some CF, small TV, stereo, fan, and a 12 volt solid-state icebox ($80 from Walmart) which I installed a thermostat in to maintain 40 degrees F. So far so good after 3 years. We only use it on weekends, so we have not run low of power so far. I am going to put more batteries, because they are almost always fully charged, and near the end of the weekends, when we use the refrig. the voltage is around 12 volts and falling. We have LP gas for water-heater and stove, and a system of pipes in the fireplace to obtain FREE hotwater. The advantage here is at 6000 feet, it is never hot and we have sufficient rain all year. Any comments or suggestions are welcome. Come on down! Frank and Ania (constructor and teacher)

Comments

  • RoderickRoderick Solar Expert Posts: 253 ✭✭
    Re: 12 volt only mountain caibn in Mexico

    Sounds wonderful! How about some pictures? Or do you have a web page?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: 12 volt only mountain caibn in Mexico

    if you think the batteries should be upgraded, i'd suggest replacing them altogether as standard marine batteries don't have long lifespans unless you went with the better batteries. adding new batteries to an old bank of batteries cause the new ones to eventually be equal to the old ones with the old battery bank's remaining lifespan in question. now the pvs you've got may be charging your present battery bank fine, but that doesn't mean you can keep adding batteries and expect it to reach full charge as it may not do this depending upon how low the charge percent goes. we don't normally recommend below a 3% charge rate, but under conditions like yours you may get away with just under 3%, meaning possibly one more battery. very iffy and that depends on the capacity of the batteries you are using presently and if your pvs are outputting as rated. too low a percentage will yield a point of not being able to fully charge the batteries even over 5 days in mexico. i'm guessing them to be around 100ah each as that is a common value for many marine batteries, but i could be wrong in my guess and they could be much lower.
    for a 200ah battery bank the approximate charge rate from 150w of pv(about 8.6amp) is about 4.3%. adding another battery yields a 300ah bank and almost a 2.9% charge rate if your pvs are delivering their rated output. rather than take a chance maybe you should upgrade your pvs as well so that you will have at least the same charge rate that you know is working for you, that being 4.3%.
  • System2System2 Posts: 6,290 admin
    Re: 12 volt only mountain caibn in Mexico

    Thanks for the info guys. The batteries are just walmart marines--cost $55 each. And yu are right, I get about 9 amps flow with good sunshine. My little refrig., which cycles on and off, uses just about the same amount of AH daily as what is produced, which is why I want to add one more battery. And, if we start using the cabin for longer periods, I will of course add more pv's. You can see photos on some of our websites, such as,
    www.villa-vacation.com/home-rental-6032.htm We also want to find a charge controller that will shunt the excess energy to a water-heater coil, rather than just shorting itself out, as this one does. frank
  • mike95490mike95490 Solar Expert Posts: 9,466 ✭✭✭✭✭
    Re: 12 volt only mountain caibn in Mexico

    How many of the 150W panels do you have ?

    Does it ever get below freezing ? You may want to put in a simple solar thermal hot water heater, less $$ than a PV panel.
    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 ,

  • System2System2 Posts: 6,290 admin
    Re: 12 volt only mountain caibn in Mexico

    I have 2 75 watt panels for total of 150 watts. It freezes once or twice a year lightly--never any freezing pipes etc. The heating coil would be just so we won't WASTE the solar energy generated. The lp gas here (for water heater and stove) is quite cheap. frank
  • rplarryrplarry Solar Expert Posts: 203 ✭✭✭✭✭
    Re: 12 volt only mountain caibn in Mexico

    Frank
    Just out of curiosity, how much is propane there? Here in northern Baja I pay 5.01 pesos per liter including IVA (tax). That is for bulk, I have a 500 liter tank. If I have him fill a small portable tank, say a 5 gallon tank he charges me 100 pesos and puts 18 liters in it.
    Larry
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: 12 volt only mountain caibn in Mexico

    if that's the same size as used by my propane gas grill i pay almost $15 to refill mine at the gas station down the road from me. i don't know how that compares with pesos.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: 12 volt only mountain caibn in Mexico

    $15 is ~164 Pesos...

    http://www.concierge.com/tools/currency

    HTH,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: 12 volt only mountain caibn in Mexico

    Larry, I pay 4.16 pesos per liter delivered. I don't know how that compares, all I know is that a 20 liter tank(8 dollars) has lasted me for 3 years so far. Hence no problem.
  • rplarryrplarry Solar Expert Posts: 203 ✭✭✭✭✭
    Re: 12 volt only mountain caibn in Mexico

    Frank
    More than 3 years on 20 liters is hardly worth keeping track of. Good for you!
    Larry
  • System2System2 Posts: 6,290 admin
    Re: 12 volt only mountain caibn in Mexico

    Wow what a dream. My Mom n Law has a place in Morelia. Maybe someday.
  • System2System2 Posts: 6,290 admin
    Re: 12 volt only mountain cabin in Mexico

    Anyone who wants to come down and see/use the cabin can have it for half-price ($18/night) if you are on this forum. I would like to get your input anyway. We are near the capital of Veracruz state, Jalapa. FRANK
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