Noob to solar - bought off-grid cottage

TorontoTim
TorontoTim Registered Users Posts: 11 ✭
in Solar Beginners Corner #1
So here's the scoop.

Bought an off-grid 2 bedroom cottage in September. The cottage itself is fully wired for 120v - 100amp breaker panel, outlets, light switches, the works.

There is a 15A line running from the panel to a shed about 20 feet away where the generator lives. It's a 4kw Yamaha model - very nice, came with the cabin.

Another 15A line (and by that I mean outdoor rated 14/2 wire) runs to the 1/2 HP water pump that sits on a small pressure tank.

It's been like that for 20 years. The previous owners had toasters, hot plates, a microwave, floor fans, a 35" tube TV with satellite, surround sound... you name it. Even a 120v water heater.

Propane powered fridge with a 420lb tank.

First thing we did was buy a propane powered, battery ignition cooking range. Next is putting in a propane water heater (tank or tankless, haven't decided).

Plan is to put a modest solar system in. Thus far, a system including the following has been suggested:

4 x 400ah (Rolls S-530 or the like) 6v batteries in 24v config
4 x 230w PV panels (Sharp)
1500w PowerBright inverter
60A Schneider charge controller
40A charger (IOTA) to allow me to top the batteries up with the generator

To manage budget, I might skip the PV panels and associated roof mounts/cable needs and start with just the battery bank. I understand this is a pretty common approach. I'd likely add panels relatively soon, and might convince myself to do it all at once, but knowing they can be added anytime takes the pressure off.

I do understand that it's good to get that 'final charge' in the batteries and keep them fully loaded between uses - we'll be up there lots, but there could be 2 weeks between visits sometimes. So either the full set of 4 panels or perhaps a single panel for that final charge?

There are just the three of us. The biggest load would be the water pump. Originally my thought was to add pressure tanks to increase my draw-down and run the pump off the generator once a day or so, and just use the solar for lighting, phone charging, and maybe my 32" LCD TV to watch a movie on a rainy night once in a while.

Power tools would be run off the generator, unless for some reason it makes sense to run the generator through the batteries and plug tools into the system served by the inverter.

Mainly want to capture more/all the power being created by the generator, and make life more convenient.

Sorry for the long intro!
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Noob to solar - bought off-grid cottage

    Welcome to the forum.

    I'm going to suggest you skip all the equipment to start with and buy a Kill-A-Watt meter first. Measure everything you use for awhile, powered from the generator. Otherwise you're just guessing about battery capacity.

    I'd also suggest you get a quality inverter-charger around 4kW right from the start. It will match what the generator can supply, and then it's just a matter of getting the right battery bank size. You can indeed run the gen to charge the batteries during the day and then use them at night. Add the panels later.

    If you pick equipment by any criterion other than supplying the power you'll use you have a 2/3rds chance of getting it wrong.
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  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    #3
    Re: Noob to solar - bought off-grid cottage

    IRIS sold at lowes has a special type of kill-A-watt system that links to any smart phone as an app, via its wifi hub. There is also insteon.



    The receptacles are called smart plugs, and via your phone you can connect smart plugs at every part of your home, it then transmits to the iris wifi and via internet you can monitor usage at each plug. You can also turn off/on each plug via the app even when you are away.

    The great thing about the iris is that its compatible with GE Z wave technology and now GE makes an inwall z wave monitoring receptical with on/off switch features.
    http://youtu.be/wF27UQQOhOE
    http://youtu.be/v9FqtkBgK3I
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: Noob to solar - bought off-grid cottage

    That 1/2 hp pump is going to have a huge start surge and demand from the inverter and thus batteries, requiring a much bigger (expensive) system to run it. You'd be WAY farther ahead to go with your idea of more/bigger storage tanks and only run the pump off the generator once a day.
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  • TorontoTim
    TorontoTim Registered Users Posts: 11 ✭
    #5
    Re: Noob to solar - bought off-grid cottage

    Totally understand the idea of metering my actual consumption to size the system. That being said, this is a recreational property that we will be spending weekends at, with perhaps a 2 week stretch between trips back to the city.

    The general daily load would consist of:

    4 x light bulbs for 4 hours (average would likely be less than this on at any given moment)
    32" LCD TV for 2-3 hours, every 2-3 days (if we get bored in the evening and want to watch a movie)
    Charging 3 cellphones daily
    Charging 2 laptops daily
    Charging 1 iPad daily

    I'm considering installing ceiling fans in the 2 bedrooms, as I understand they consume relatively little wattage vs. a table top fan (75w has been suggested for each ceiling fan) to move air on hot summer nights.

    The large load would be the 1/2 HP water pump serving 1 bathroom, 1 kitchen and 3 people. And once a week or so a vacuum cleaner.

    Using one of the various 'sizer' calculators I've found, I come up with about 1,400 daily average watt-hours not including the 1/2HP water pump. At 700 watts, I could see it running a total of about 30-60 minutes a day or so, but that's a bit of a guess and I have to confirm the start-up surge.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: Noob to solar - bought off-grid cottage

    I can understand why you wouldn't want to sink big money into a system that isn't going to be used all the time. That's exactly what we're trying to prevent here. Anyone can build a huge off-grid system that will power everything they've got; all it takes is money. But unless you're Bill Gates ....

    Two reasons why calculation power use doesn't work:
    1). The numbers supplied by the maker are often a work of science-fiction;
    2). People are really bad at estimating how long they actually use anything, especially if they are thinking about using it at the time.

    A few years back it was hot enough at the cabin to need to run a fan over night. I used a pedestal fan, and on low it used 35 Watts. You have a 'guestimate' of 75 Watts for a ceiling fan. That's a difference of 40 Watts and overnight that can be 480 Watt hours: the same amount of power a large inverter uses running for a full day. Those little things add up really fast.

    Here's a plan to consider: Get a good inverter-generator instead of a full panel array. Have enough battery capacity to supply your over-night needs. Run the gen to charge when needed and operate large loads. Have enough PV to keep the batteries charged when you're not there.

    In case you're wondering: we started out with no electric, added a 3kW Onan, then a small panel for the battery to the radiophone, then a small inverter to run the computer (to work while on vacation!) and some more panel to maintain the batteries, then a larger inverter with more battery and more panel, and then the sizable system we have now. I'd still add to it if I could. But at least I don't need to increase the inverter, just more panel and battery would be nice. (This is mainly the difference between 'occasional use' and 'nearly full time' at the place.)
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