Combined wind and solar

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I have 2 customers interested in a combined wind and solar energy system. One is on the grid and one off. I am wondering what charge controllers/inverters are going to do this the best.

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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Combined wind and solar

    i think your inquiry is too generalized to really answer with a specific opinion on them. i'm assuming both will utilize batteries. as to controllers the larger systems use larger capacity controllers or even more controllers than 1. i do recommend having the battary terminal sensor to track more accurately the proper charge voltage. if mppt is used, it is on the larger systems and does have some advantages with an increased initial cost.
    the inverters may be determined by the power usage of the customer and battery capacity available(during no grid power). how true of a sinewave is another factor. the quantity of inverters may be a factor of the max power needed by the customer. as somebody needing only 1kw at any peak will differ from the customer whose peak may be 4-5kw. the larger 4-5kw peak will almost certainly be more than one inverter that is stackable. there's also the ability to have power available like 220vac that is splitable to the 110vac legs.
    in general what the customer wants does narrow down the equipment that shall be purchased. some decisions they don't make like one brand over another can be yours to make.
  • System2
    System2 Posts: 6,290 admin
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    Re: Combined wind and solar

    Well my question is: Is there a charge controller that handles wind and solar inputs simultaneously. One job is completely off the grid. I have picked out an MX60, 4 evergreen 115w modules, a samlex 1000w sinewave inverter and 8 12v/79ah batteries configured for 24 volt. The customer is also interested in wind power so I am looking for something other than the MX60 that will accept two power sources, unless the outback does that already, I haven't had time to wade through the manual yet. (Pardon me for not rtfm)
    I have the grid tie figured out for the most part, there is an Aurora inverter that will power track two different inputs. I have more homework to do on the whole thing obviously. I left out the details on the original post because I was just inquiring about one piece of equipment to handle the solar and wind.
    Pat
  • BB.
    BB. Super Moderators, Administrators Posts: 33,533 admin
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    Re: Combined wind and solar

    You probably need to work closely with the wind turbine supplier(s) that you think you want to use... The differences between various wind turbine models and manufacturers probably limits the ability to pick a one controller solution that can manage the energy from both solar and wind.

    Solar PV is just DC and the number of panels you plug in. Wind turbines many times have their own charge controllers (either built in) or in some case use three a phase alternator and a downstream controller to rectify and manage the energy. There does not seem to be one "standard" solution/interface.

    There were a few posts here from somebody that seemed to be pretty successful with wind... You probably have already looked through the new wind section here:

    http://www.wind-sun.com/smf/index.php?board=9.0

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Combined wind and solar

    at this time a universal type controller for both does not exist. more controllers that can do more are soon to emerge, but will still not encompass every circumstance and need of a customer. this panacea controller may never exist, but it is not impossible for some gaps to be bridged as some will be. we are still awaiting the final word on the classics controller and hopefully it will be soon.
    comments from robin or boB as to what they will allow for public knowledge at this time for their upcoming controller along with preliminary time frames are welcome from them. it has been some time since hearing any further news that would be releasable to the public.
  • System2
    System2 Posts: 6,290 admin
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    Re: Combined wind and solar

    I would simplify. If the batteries are large enough you can stack all of the charge controllers you want to --on the positive/ negative bus's. A solution for your grid-tie customer might also be a Xantrex 4024....set to sell to the grid with the parameters he chooses. Then, the battery system can be seen as back-up power as well. I might point out that a good SW inverter is basically responsible for a few hundred feet of wire (household etc) and can be very clean power--perhaps cleaner than grid connect.

    I like your idea of a central dc charge controller--if it had MPPT features. In a way--all of your charge controllers do communicate--as they read the same thing--at the battery pos/neg.

    Good Luck!

  • AFWnS
    AFWnS Solar Expert Posts: 13
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    Re: Combined wind and solar

    The Bergey wind turbine (bergey.com) puts out a hybrid system with a power center with both a wind (24V) and PV input that does a nice job into a 24V battery bank. and it has provisions to mount the PV on the wind tower.
  • System2
    System2 Posts: 6,290 admin
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    Re: Combined wind and solar

    Does a charge controler dedicated to wind turbinre power ?
    I am thinking to the problem to buck-boost tension when the wind is weak, and the problem of the overload when the wind is too strong, both regarding the nivel of charge and voltage of the bank of batteries.

    jacques
  • BB.
    BB. Super Moderators, Administrators Posts: 33,533 admin
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    Re: Combined wind and solar

    Buck switch mode power supplies are, if I recall correctly, more efficient than the boost and buck/boost supplies... So, if one is trying to design a low loss system, the unregulated voltage should be higher than the battery voltage (typically 1-2 volts minimum) for best results. Using other topologies will work, but it would take some study to figureout of the overall efficiencies and energy gathered for a real world system favor one type or the other.

    If the controllers are designed correctly, they will simply be sized (heat sinks, wiring, FETs, etc.) to handle the maximum output of the wind turbine.

    The issue of the wind being too strong comes into play, typically, the controller draws current (power) from the turbine to keep its speed in its operating range. If the batteries are charged, then the controller will dump the excess energy to a secondary load (typically a simple resistive heater--although some folks have connected an electric water heater to capture waste heat).

    If the wind is too strong, then the turbine will still overspeed (too much torque for the alternator/generator to absorb). Next would be physical limiters... Could be the tail will move the blades to right angles wrt the wind, or a mechanical brake, flexible blades, or even breakable links that feather the blades have all been used. And each, has its own pros and cons...

    In my area, as an example, a couple decades ago they put in wind powered runway lights at the local airport. Used mechanical links to feather the blades in an overspeed--and after a couple of those events over a year where they had to (don't remember which) either pull the generators down or go up in a cherry picker to fix--they simply took the wind generators down and used the towers for cell phone repeaters.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Frank
    Frank Solar Expert Posts: 54 ✭✭✭
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    Re: Combined wind and solar

    If the wind turbine doesn't have it's own dedicated controller, I would use a MPPT controller as part of the "amp generation equipment" on the PV and also feed the wind output directly to the batteries. NEC requires two diversion controllers (when used) and these can control max voltage seen by the batteries (by dumping excess amps into a water heater equipped with DC heating elements).

    I've also heard that Sunny Boy has a MPPT grid-tie inverter designed for wind.