Solar and Wind combined, pitfalls?

Hey guys, i did search but i have to admit only lightly did i browse for answers, i dont know if it was my wording or what but it didnt seem to list anything to useful. I just have a simple question (im sure with many varying complex answers)

As discussed before, im planning on a solar setup for power, off-grid, pretty highly efficient (hopefully =P) and i wanted to discuss the possibilties of adding a wind generator to suplement the days when perhaps there is little sun but good wind and/or at night. I havnt looked into the area im building in and what kind of wind patterns there are but assuming they are atleast average i was curious more so as to the direct problems with the interaction of the two systems assuming they are too different.

So the short version, are there any major problems with combining wind and solar systems to charge the same battery bank and power a home?

I know there is a great deal of more information you'd probably like to have but i wanted to generalize this post from the situation specific.


  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    Re: Solar and Wind combined, pitfalls?

    Answer .the short version ..... no problems what so ever in combining the two sources of renewable energy in one system !

    The long answer......this forum is generally not a lover of small to medium wind turbines from a performance per buck point of view. From what Ive read over the last six months.

    I have a 1kw unit to errect and fly and its dropped down my list of things to do since being a member here.

    I will say a good site wind evaluation is a no brianer before even thinking about committing $ to propellors .

    Let the big boys load, aim and fire now.
  • Telco
    Telco Solar Expert Posts: 201 ✭✭✭✭✭
    Re: Solar and Wind combined, pitfalls?

    Here's a wind-centric site for you to check out. These folks are deep into it, up to and including wrapping their own windings to build their own wind generators from raw materials.

    I think wind makes a fine backup to a solar setup, as the wind is usually blowing when the sun isn't shining, but you also can't count on getting the full rated power from wind, more like a trickle. Some of the sites I've seen have recommended getting a weather station that can record wind speeds 24 hours a day, and leave it in place for a year to see if it really would be worthwhile to run wind.

    Given a choice, I'd also suggest doing a vertical turbine over a horizontal turbine based off my own research into them (not actual experience, damn it all! :grr:grr). Vertical turbines have many advantages in that:

    1. The alternator is at an easy to maintain ground level.
    2. They are quieter than horizontal models.
    3. There is no need for them to turn to orient themselves to the wind.
    4. The faster they go the more solid they appear, so birds won't try to fly into them.
    5. They can be made to look really cool.

    This site is the Otherpower forum to ask more about them. And, here's a few links that I thought were worth saving. (these guys make the cool looking ones)
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Solar and Wind combined, pitfalls?

    Hybrid systems that combine PV and wind to charge a single battery bank are not unheard off. However, there’s an architectural issue that must be addressed.

    Relatively speaking, charging a battery from a PV source is easy. Basically, you just hook PV modules to a charge controller, and then the controller to the batteries. The controller limits charge voltage to the batteries using an electronic PWM approach to rapidly open and close the connection between the PV array and the controller and varying the duty cycle. When the connection is open and the array is unloaded, it operates “open circuit”, and there’s no harm done, except for the potential energy that’s not harvested.

    Energy from wind generators must also be controlled, but alternators really don’t like running open circuit. The popular solution is to connect a “diversion load” (i.e., a resistive water heater element or a resistive space heater element) that’s essentially in parallel to the battery bank. The basic idea is for a diversion controller to shuttle “excess” energy to the diversion load and thus control charge voltage to the battery bank.

    The Morningstar TriStar charge controller is an interesting product that can be user-configured as a PWM solar charge controller, OR a diversion controller, OR a load controller. Its user manual contains useful discussions of all three applications.


    In short, a hybrid system can be done. It just needs to be well thought out in advance.

    Jim / crewzer
  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    Re: Solar and Wind combined, pitfalls?

    My wind turbine came with its own controller and dump load, 3 wires from the wind turbine to the controller, two wires from the controller to the batteries and another two wires from the controller to the dump load, the only two wires that must be polarity correct are the two obviously to the batteries, the other wires just fit to the terminals . HTH
  • System2
    System2 Posts: 6,290 admin
    Re: Solar and Wind combined, pitfalls?

    This is just the kind of info i was looking for, and as far as the design limitations and the load required as a diversion load is fine, considering that i will be using a solar shed with hot water storage i can also have a water heater element to suplement that within reason as the diversion load, if the energy is going to be "wasted" why not use it instead or perhaps even a water pump or something silly if that doesnt work to water my lawn or light up eat at joe's sign.

    Regardless I really appreciate all the good links you guys gave me, very very helpful and it looks like i'll be joining some other forums to see if i can help answer questions and create plenty of my own.

    lastly, if anyone has any information that hasnt been covered, by all means slap it on us. Im hungry for knowledge.

    One thing though as im not exactly fully grasping the technical implications to having 2 chargers to the same battery bank and how that would affect each charger, would it be better, perhaps safer and or more cost effective to find a controller that will handle both a PV and Wind source as well as providing a diversion load etc needed by the Wind side of the controller?