Solar Cottage on an Island

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Comments

  • GaryOGaryO Registered Users Posts: 27
    Another important consideration about the propane generator is that it burns cleaner and produces less CO than the gasoline equivalent. My cottage is up on stilts and sits 4-6' off the ground, so I get a little more piece of mind running the propane generator around the perimeter of my dwelling vs gasoline. Although I will use a CO monitor inside, regardless.
  • BB.BB. Super Moderators, Administrators Posts: 29,517 admin
    Gary,

    Sounds good. As long as you take everything into account regarding generator/solar/battery/operation/fuel when you make your decisions--No surprises is what I am after.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,665 ✭✭✭✭✭
    The Honda EU 6500is has an oil change interval of 100 hours or 6 months BTW. You may have been confused by the initial break-in interval.
    Where I live in Mariposa CA our dump has lot's of Generac gear in a pile. I am not saying that the models you like are in that pile but....
    I have one client who may have never changed the oil on a 6500i
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BB.BB. Super Moderators, Administrators Posts: 29,517 admin
    OK--A rules of thumbs project review (I can do that! :p):
    • 48 volt * 415 AH battery bank * 0.85 AC inverter eff * 1/2 days of storage * 0.50 max discharge = 4,233 WH = 4.2 kWH per day
    That is a very capable system... And as long as you are reasonably conservative in your energy usage--A full size fridge, LED lighting, Radio, Laptop Computer+Networking, TV, clothes washer, water pressure pump) should all be doable.

    AGM batteries, should usually be recharged every 3-6 months (self discharge). Cold weather, very happy batteries in storage. Small solar array on side wall for winter charging and shedding of snow (if applicable).

    Charging your battery bank, 5% to 13% for solar power:
    • 57.6 volts * 415 AH * 1/0.77 panels+controller losses * 0.05 rate of charge = 1,552 Watt array minimum
    • 57.6 volts * 415 AH * 1/0.77 panels+controller losses * 0.10 rate of charge = 3,104 Watt array nominal
    • 57.6 volts * 415 AH * 1/0.77 panels+controller losses * 0.13 rate of charge = 4,036 Watt array "cost effective" maximum
    With AGMs, and weekend/seasonal living, you can get away with 5% rate of charge. For full time (9+ months a year), and normal family living, then 10%+ is usually a better choice.

    Hanging the panels on the shoreline--Certainly a possibility but theft/storm damage always a concern.

    Regarding sizing for loads--Hours of sun / location / shading is all important. Where (roughly) is the island (I did not anything earlier). If you are in the North East, you can be seeing less than 3 hours per day of useful sun outside of the 6-8 "sunny months".. Call it 3 hours a day "break even":
    • 4,233 WH * 1/0.67 AGM based off grid system eff * 1/3.0 hours of sun = 2,106 Watt Array "break even" at ~3 hours of sun per day
    So your planned solar array looks good for you needs (and possible shading issues). Just remember, even a partially shaded array/panel can dramatically reduce power output of the system.

    And using the 1kWatt of AC inverter and Solar Array per 100 AH @ 48 Volts -- Then around a 4.15 kW AC inverter and Solar array (maximum recommended size of inverter and array for that battery bank configuration) would fit nicely with your present battery bank.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,665 ✭✭✭✭✭
    It does sound good except for the cooling load and the panels being shaded. What was the saying about the difference between an optimist and a pessimist?
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • GaryOGaryO Registered Users Posts: 27
    BB. wrote: »
    OK--A rules of thumbs project review (I can do that! :p):
    • 48 volt * 415 AH battery bank * 0.85 AC inverter eff * 1/2 days of storage * 0.50 max discharge = 4,233 WH = 4.2 kWH per day

      -Bill

    Thanks for your feedback, Bill. Gives me more confidence that I'm doing this right! I don't have any of the equipment yet, those are all just items I came up with through recommendations and research.

    The property is in Midwest Ohio. According to the charts I have looked at, I have 4.2 sun hours per day.

  • GaryOGaryO Registered Users Posts: 27
    The Honda EU 6500is has an oil change interval of 100 hours or 6 months BTW. You may have been confused by the initial break-in interval.
    Where I live in Mariposa CA our dump has lot's of Generac gear in a pile. I am not saying that the models you like are in that pile but....
    I have one client who may have never changed the oil on a 6500i

    You're probably right, I may have been remembering the first change. The GENERAC recommends 500 hour interval which is really nice (provided it lasts that long).
  • BB.BB. Super Moderators, Administrators Posts: 29,517 admin
    Just remember that solar power (usually) varies quite a bit with the seasons (and even local weather). Using PV Watts for Dayton OH, fixed array tilted 40 degrees from horizontal:


    Month
    Solar Radiation
    (kWh/m 2/day)


    1
    3.08


    2
    3.54


    3
    4.08


    4
    5.17


    5
    5.32


    6
    5.54


    7
    5.44


    8
    5.68


    9
    5.05


    10
    4.79


    11
    2.88


    12
    2.36


    Year
    4.41



    You can see that a yearly average is one thing--Actual month by month long term average is different...

    Typically, I toss the bottom three months as being Generator Assist months. And that gives February at 3.54 hours of sun per day as the "break even" month (where you may or may not need to use the genset).

    Of course, you power usage will vary over the seasons too (refrigerators use more in the summer, you use more lights/TV in the winter, or perhaps you are not even there during the winter, etc.)... And, you can add more panels to have less genset run time (solar panels have never been cheaper, and fuel is going up again in our area).

    Power usage is a highly personal set of choices. And conservation is usually the first / best investment (i.e., find the lowest power Refrigerator, laptop computer, electronics, lighting you can). It is almost always less costly vs design a larger system and running the generator more.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GaryOGaryO Registered Users Posts: 27
    BB. wrote: »
    Just remember that solar power (usually) varies quite a bit with the seasons (and even local weather). Using PV Watts for Dayton OH, fixed array tilted 40 degrees from horizontal:


    Month
    Solar Radiation
    (kWh/m 2/day)


    1
    3.08


    2
    3.54


    3
    4.08


    4
    5.17


    5
    5.32


    6
    5.54


    7
    5.44


    8
    5.68


    9
    5.05


    10
    4.79


    11
    2.88


    12
    2.36


    Year
    4.41



    You can see that a yearly average is one thing--Actual month by month long term average is different...

    This is also great info that I hadn't seen before, Bill. I knew it varied but not that much. However, I think this helps my case. I will be iced off of the lake typically in late November, not returning until it thaws in April. I could walk across if I really felt motivated to visit, but that is the only way out there in the winter. Looks like I will average 5+ sun hours for most of my usage. Might get tight in November.
  • GaryOGaryO Registered Users Posts: 27
    Ended up buying the 6kW Generac ECOGEN system to get me going. With the $1500 incentive, I will only have $1,845 in it before tax, so it is a very cost effective starting point.

    Have the wiring inside the cottage about 80% complete, so I can use this to test all of my circuits and run my air conditioning while I install the knotty pine interior.
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    GaryO wrote: »
    Since I will have canisters of 24g of propane, 0.7g/h of propane would allow that canister to last for 34 hours of continuous runtime. I can probably live with that

    Youre kidding right? 24 gals of propane in 34 hours. And youre talking about long runtimes. Sounds not really like a holiday!

    With your solar shade issues, theft, part time use investment etc, id be looking at a genset/battery/inverter combo. Run the genset hard and fast then turn it off. One 80W panel to keep the battery topped while your gone.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • GaryOGaryO Registered Users Posts: 27
    zoneblue wrote: »

    Youre kidding right? 24 gals of propane in 34 hours. And youre talking about long runtimes. Sounds not really like a holiday!

    With your solar shade issues, theft, part time use investment etc, id be looking at a genset/battery/inverter combo. Run the genset hard and fast then turn it off. One 80W panel to keep the battery topped while your gone.

    There will be 2 canisters, one running and one on deck. Plus, that load level is assuming 50% generator load all the time - and I don't expect to go much above 20% generator capacity. I can easily go 4-5 days purely on propane, if needed.

    My ultimate plan is to get an inverter and solar array hooked up this fall. Given the costs, I am simply doing a little at a time so that I can continue to pay cash for everything.

    Theft isn't a major concern for my generator. It weighs 380lb and is lagged to a concrete pad.
  • BB.BB. Super Moderators, Administrators Posts: 29,517 admin
    Regarding theft... Lagging it to a concrete pad is not going to slow down a determined thief. They have pulled well pumps and even taken entire small cabins.

    If there are others that live in the area when you are gone--Setting something up that can broadcast a signal to your neighbors and attract their attention would not hurt. Even setting up a game camera where you can see if people are scoping out the place may help.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    I was talking more about the solar panels. You put a few grand of panels outdoors, with nothing more than a few nuts and bolts holding in down in a quiet out of the way place. There are security screws, but its just worth factoring.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    Remote locations are a mixed bag. Remote means that not many thieves will become aware of whatever there is to steal. But if someone does discover the goodies the remoteness permits them to take whatever time is needed to dismantle neatly or otherwise. We have been very fortunate with our remote location. Knock on wood. [raps head lightly] :D
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • GaryOGaryO Registered Users Posts: 27
    Although I'm remote in the sense that it is an Island, I'm only 1/4 mile offshore from several homes. Theft is still a concern, but no one is going to take this without someone noticing...
  • mike95490mike95490 Solar Expert Posts: 8,380 ✭✭✭✭✭
    no one is going to take this without someone noticing...
    hey Gary, we saw your crew moving all that solar stuff last week, just after you put it up.

    What could go wrong - go wrong - go wrong
    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 ,

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