sizing up a system

i''m looking at going completely off grid all together. how do I determan what size system I need for my house?? I want to do solar and wind together. in a way I would have no choice to do both because of the winters. solar panels wont generate if there covered with snow and ice. I have already been shocked at how expensive this can get and had the eye opener:D

Comments

  • AguarancherAguarancher Solar Expert Posts: 282 ✭✭✭
    Re: sizing up a system

    The system size will depend on what you want it to power, only you know that. Is the grid available? Where are you located?
  • BB.BB. Super Moderators, Administrators Posts: 29,189 admin
    Re: sizing up a system

    Loads are the #1 information we need to help. Conservation will be important for you too (it is cheaper to conserve power than to generate power).

    Also, you may have wide seasonal power needs too... Irrigation and circulation fans in the summer. Perhaps even business services (tourists) and refrigeration for food. In the winter, more lighting, but perhaps less refrigeration/freezer usage in winter. Or, perhaps you need more power in winter (more lighting, circulating fans, circulating pumps, etc.).

    You may get over 5 hours (with fixed array) or even >8 hours (with 2 axis tracking array) worth of sun in the summer, and less than 3 hours in the winter...

    In general, it is difficult to get good wind turbines off the shelf... But if you can build your own and put it on a 60-90 foot tall tower (30' higher than nearby trees/buildings, etc.), you may have a chance of getting quite a bit of power from wind. Most turbines do not do that well in harsh weather (too low of wind, no power; too high of wind, turbines may over speed/over heat).

    More or less, to set expectations:

    1,000 WH per day (1 kWH per day, 30 kWH per month)==Cabin with lights, laptop computer, pump for presurizing plumbing, small well pump, small TV+Radio, etc.
    3.3 kWH per day (100 kWH per month)==A full off grid home + refrigerator, +well pump, +clothes washer, etc... Close to "normal" electrical life
    10 kWH per day (300 kWH per month)==A very efficient home with central heat (natural gas, propane, oil)--multiple computers, another refrigerator/freezer, etc.
    33 kWH per day (1,000 kWH per month)==Standard North American home (not much A/C, not much in way of conservation)
    100 kWH per day (3,000 kWH per month)==Add full A/C (Texas, Florida), electric heat (up north), etc.

    The first system (1 kWH per day) is a "small off grid system" that is not too much money (less than $10,000 ????).

    The second system (3.3 kWH per day) is a "medium system"--Possibly $30,000 price range (prices are highly variable, just SWAGs to give an idea).

    The third system at 10 kWH per day) is about as large as most people can justify.... Anything larger, is difficult for most people to justify.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • speed_racerspeed_racer Registered Users Posts: 2
    Re: sizing up a system

    iv'e just been doing some research and I can say I got some real eye openers :D as far as cost to go off grid. yes the grid is available where I am so I am thinking that it might be more beneficial just to tie into the grid instead of going completely off the grid.
  • solar_davesolar_dave Solar Expert Posts: 2,339 ✭✭✭✭
    Re: sizing up a system
    iv'e just been doing some research and I can say I got some real eye openers :D as far as cost to go off grid. yes the grid is available where I am so I am thinking that it might be more beneficial just to tie into the grid instead of going completely off the grid.

    The key to grid tie is to know your utility net metering plan and how they account for your excess production on good days.
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Re: sizing up a system

    The key to going off grid and solar in general is to know why you are doing it. If its to save money ,well, for now forget it. The price of renewable energy is falling, but itll be some years before its a money maker. The major exception to this is as soalr dave said, if you are lucky enough to have a really nice incentives/FIT/NEM.

    The second major exception is where you have a very high initial grid connect charges, at least 30K plus.

    Lastly people can and do go off grid for philisophical reasons, and they are essential the pioneers that support the off grid industry. Imagine if even 10% of a city decided to install an off grid setup, it would significantly reduce the need for dangerous non renewable technolgys like nuclear and coal.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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