Solar to Wind ratio?

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Steven Lake
Steven Lake Solar Expert Posts: 402 ✭✭
in General Solar Power Topics #1
I've been looking all over for this answer and alas, I have nothing. My question is this. If I wanted to supplement some of my off grid power needs with wind to reduce how much solar I need to supply my requirements, what percentage would be required and classified as "safe" IE, 60% solar, 40% wind? And if so, what's the minimum recommended wind input to make that a viable solution? I ask because I'm quickly coming to the realization that what I'd need to fulfill all my energy requirements is gonna completely torpedo the wallet into a sniveling whimpering little pile of goo. But since I can do wind for roughly 1/3rd of what I can do solar, I figure that might be my ticket to making everything work without bankrupting myself. Anyhow, what's your suggestions on this? Also, fyi, my local wind average speed is 12mph over a 24hr period. The winds also tend to be strongest at night, weakest during the day. Anyhow, help is welcome as always. :)
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #2
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    Re: Solar to Wind ratio?

    How do you come up with 1/3 the cost?
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  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    #3
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    Re: Solar to Wind ratio?

    I have found that my wind cost about 10 times the solar and that I get nothing except during the occassional storm and then it is hard to control.
    gww
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #4
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    Re: Solar to Wind ratio?

    The way I would look at the question--Figure out when solar is "cost effective" for you--And then enough wind in the season to make up for loss of solar that would have been suplimented by generator run-time.

    For example, using PV Watts, fixed solar array tilted to 42.4 degrees from horizontal near Detroit Mi:




    Month
    Solar Radiation
    (kWh/m2/day)


    1
    2.90


    2
    3.59


    3
    4.13


    4
    4.84


    5
    5.52


    6
    5.58


    7
    5.42


    8
    5.48


    9
    5.18


    10
    3.96


    11
    2.59


    12
    2.15


    Year
    4.28




    Solar power is pretty cost effective at 4 hours of "noon time equivalent" sun per day. You can add panels to make up for poor winter sun--But you would have to double the array for December. So--assuming you have enough panels to run March through October with solar--Then you would want either to add panels, or run enough wind power to make up for the dark days of winter.

    Do you have any performance numbers from an existing wind system in your area? Do you have any turbine models/towers that interest you?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Steven Lake
    Steven Lake Solar Expert Posts: 402 ✭✭
    #5
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    Re: Solar to Wind ratio?
    solar_dave wrote: »
    How do you come up with 1/3 the cost?
    That's just a rough number in my head. But it sounded good. :)
    BB. wrote: »
    Do you have any performance numbers from an existing wind system in your area? Do you have any turbine models/towers that interest you?
    Well, the system I'm looking at is used by a bunch of people in our area and is 1000 watts max. But with our wind and the amount of wind it takes to really get it really generating, the average for the whole day is about 100-200 watts per hour (depending on location) averaged across the entire 24 hour period. The exact model I haven't settled on, as it seems like everyone's got their pet preference, so we've got everything around here from home brew to Aleko, Sunforce, etc. But merely talking to people got me those averages I gave you as I couldn't find any official single home numbers as the only available stats online are the big multi-megawatt jobs.
    BB. wrote: »
    Then you would want either to add panels, or run enough wind power to make up for the dark days of winter.
    Yeah, that was part of the idea of adding a windmill to the solar was to pick up the slack whenever the solar couldn't produce enough. It seems that winter would be the primary time when that would be applicable given the low solar hours and generally high and frequent winds.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #6
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    Re: Solar to Wind ratio?

    So--How much power do you use, and how much (if any) solar power do you have?

    How big of battery bank (AH @ Volts)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #7
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    Re: Solar to Wind ratio?
    Steven Lake wrote: »
    But with our wind and the amount of wind it takes to really get it really generating, the average for the whole day is about 100-200 watts per hour (depending on location) averaged across the entire 24 hour period.
    It may seem like a small quibble, but it is important:

    You do not average 100-200 watts per hour. You average 100-200 watt-hours per hour. Or the average wattage over the 24 hour period (not per hour) is 100-200W.
    SMA SB 3000, old BP panels.
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #8
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    Re: Solar to Wind ratio?

    Here's some averaged figures. System has 1kw SWWP |H80 wind turbine, 2.1kw pv (generator, some utiloilty too). The wind average over 10 yuears is 560kwhrs per year, solar 2300kwhr per year. The wind provides about 25% of the renewables for a year, the solar 75% (not total energy, generator and utility do the rest, another couple of hundred kwhrs).

    I looked at replacing the wind turbine this spring (fixed it instead). Cost for turbine and controller was going to be about $6K USD. How much do you think 1kw of pv installed would cost...maybe $2K racking, controller and all in? Wind can be nice when there's no sun (March, December, night), but it really pales when you consider the upkeep/maintenance that goes along with it...compared to pv (nothing beyond changing angles 2-3 times per year so far).

    Money won't be spent on wind here anymore. Well, bearings only cost $30 every 5 years, but no replacement of turbine...more pv.

    Ralph
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  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    #9
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    Re: Solar to Wind ratio?

    One other thing, I do get more wind in winter. I have a fixed solar aray set for winter and actually produce more on short winter days then I do on long summer days, although due to clouding my monthly average is about 16 kwh daily winter and 20 kwh summer. My short winter days give about 32 kwhs but more of them are cloudy. My summer days are about 26 kwhs. My turbins give about a 800 watt daily average winter and maby 20 watt average summer. My turbines are on an 80' pole and a 40' pole and I live in a wind zone two.
    Hope this helps.
    gww
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  • Steven Lake
    Steven Lake Solar Expert Posts: 402 ✭✭
    #10
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    Re: Solar to Wind ratio?
    BB. wrote: »
    So--How much power do you use, and how much (if any) solar power do you have?

    How big of battery bank (AH @ Volts)?

    -Bill
    Well, I'm looking at only really needing about 250ah@24v. As for current solar, we don't have any for this location. At least not yet. This is right now a theoretical project to figure out where I want to sink my cash when we do finally do it.
    inetdog wrote: »
    It may seem like a small quibble, but it is important:

    You do not average 100-200 watts per hour. You average 100-200 watt-hours per hour. Or the average wattage over the 24 hour period (not per hour) is 100-200W.
    Well, that's what I meant. 100-200wh per hour. The unit I'm looking at is rated at 1000w peak, but in our wind and given the runup curve (sucky output at low RPM, improves exponentially with speed increase) I'm only realistically expecting 100-200wh per hour out of it. I might get more, but I'm trying to be a bit conservative so I don't hang myself needlessly by underestimating production.
    Ralph Day wrote: »
    Here's some averaged figures. System has 1kw SWWP |H80 wind turbine, 2.1kw pv (generator, some utiloilty too). The wind average over 10 yuears is 560kwhrs per year, solar 2300kwhr per year. The wind provides about 25% of the renewables for a year, the solar 75% (not total energy, generator and utility do the rest, another couple of hundred kwhrs).

    I looked at replacing the wind turbine this spring (fixed it instead). Cost for turbine and controller was going to be about $6K USD. How much do you think 1kw of pv installed would cost...maybe $2K racking, controller and all in? Wind can be nice when there's no sun (March, December, night), but it really pales when you consider the upkeep/maintenance that goes along with it...compared to pv (nothing beyond changing angles 2-3 times per year so far).

    Money won't be spent on wind here anymore. Well, bearings only cost $30 every 5 years, but no replacement of turbine...more pv.

    Ralph
    Wow, only 25%? Hmm, as for the price of the turbine, I'd come up with figures much lower than that. At least in my initial pricing. But then again, when I started this thread my pricing for PV per watt was a lot higher than my wind pricing. But that's since changed thanks to a friend who tipped me off to a guy selling local who has a good reputation, sells good panels (It's a German company, but I forget the name) and they're 2/3rds the best price I've found so far. So with what you said, and his prices, I might be able to bow out of wind entirely. I'd considered it as a way to lower my overall investment, but since getting this new pricing and based on what you told me, that may not be needed.
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