westend wrote:
Cons: need to keep panels clean, need to tilt or loose 30-45% output, needs full sun, doesn't work at all nights, raining, snowing, etc.
I don't believe that full-time tilting is going to net a 30-45 percent increase in harvest, especially in the Summer. I tilt my panel in the Winter, when in storage. And you've just reminded me that it may need a cleaning after 3 years. Also, I am harvesting a very small bit of power even after sunset when the sky is still light.
The biggest trick with solar is to size battery capacity and amount of module wattage to one's needs. After that, solar does a better job of charging my batteries than I can with all manner of 120V chargers.
I also have a small wind generator. What is typical with small wind is that power doesn't reach meaningful amounts until prop size diameter reaches 10'. That is fairly hard to transport in an RV. Also, wind speeds increase dramatically with height. 30' of height is typical installation dimension. I am still experimenting with the windmill, trying to find the best DC permanent magnet motor since I want a simple DC-DC path. My current setup is a 15' mast with a three blade aluminum airfoil propset. The shaft is carried by two pillow block bearings so noise isn't an issue. You can't hear it turn when standing next to the mast.
Correct.
Small turbines with small prop blades (under 10ft) are not able to "harvest" much energy from the wind. For that reason small turbines must run fast in order to harvest a "meaningful" amount of energy.
Contrast that with prop blades over 10 ft which are able to harvest more energy at slower rotations.
Height DOES matter, the closer to the ground the less wind you are able to capture and not to mention the slower the wind is.
Serious RE enthusiasts will often mount their turbines on towers, often 30ft or a bit more. This gets the props into faster moving air and helps reduce turbulence the air encounters.
Turbines also need to be in the open, buildings, trees or other tall obstacles cause turbulence which slows down the air around the turbine.
One should note, I am not against wind turbines, in fact I have really tried to justify building one myself.. But the fact is where I live and where I camp I simply do not have enough days of CONSTANT 10 MPH winds or higher.. Once you drop below 10 MPH there is very little energy left in the wind to harvest..
7 MPH is the very bottom windspeed that will net ANY noticeable charging in any wind turbine. Slower than that and the blades easily will stall out.
For the money you will spend on pipe, wire and a commercial made wind turbine you will have pretty much as much as a Honda 2000i inverter gen. And unless you camp in a place that has constant 20-30 MPH winds you will net next to nothing in charging.
One needs to remember that even if the prop is spinning, it MAY NOT be making power.. Some folks seem to think it makes power anytime the prop spins, that is not true, the wind gen must see enough speed to even get enough voltage above the battery voltage (IE cut in).