solar panels or wind turbine battery charging?

You don't give a lot of information on what you plan to do while "off grid"

To give you some idea of what is possible, I'll give you my setup and usage.

We have a 25 ft 5th wheel, Battery is used for lighting (all LED), reefer, hot water heater, furnace, radio, and a small inverter DVD/TV (2 hrs couple of times a week).

We have 2 6V GC batteries, 2 60 watt panels flat mounted on the roof of the RV, and a 100 watt portable panel that can be placed away from the RV if in the shade. Have a PD9260 converter/charger with pendant, and a Honda 2K invertr gen.

We've added fresh and grey tanks, and can go up to 10 days totally "off grid"

In summer we can usually go with the 120 on the roof. In winter we often also use the 100 portable as the furnace is a big draw, and there is less sun. We occasionally need to also use the generator (mostly in winter).

Were I to do it again, I'd put 200 watts on the roof, get a PD9245 and get a 1K Honda inverter gen.

Regards,
Doug

wanderingbob wrote:
Many years ago in a galaxy far , far away we lived on a 49 foot ketch in the trade winds . We ran our refrigerator VIA a wind generator mounted on the mizzen and had no problems for over ten years . Twelve volt living has been common on boats for 40 or 50 years.

Wind on sea is a bit different than on land.

On the sea, you have vast open space, winds can stay rather constant and in the same direction for hrs and even days at a time.

On land, you have trees, hills, valleys, buildings all which reduce the windspeed drastically at heights under 30ft above the ground. This affects the direction and speed of the wind and how constant it will be.

I don't know about you but I personally have no interest in dragging 10, 30, 40, 50ft of pipe or tower let alone build and guy a pipe mast or tower then find a way to get it up in the air. Seems to me there are other means of getting power without going through this kind of hassle.

If spending a bunch of money on a big rotating yard ornament is your gig, then go ahead.. But don't expect it to be able to bring much if any meaningful energy to the plate.

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).

Many years ago in a galaxy far , far away we lived on a 49 foot ketch in the trade winds . We ran our refrigerator VIA a wind generator mounted on the mizzen and had no problems for over ten years . Twelve volt living has been common on boats for 40 or 50 years.

The OP did not really give enuff info , such as how long are ya gonna dry camp , what kinda batteries have ya got , what will ya try to run off of the batteries ? If its just 2 days at a horse show just add another battery and conserve , if its a month in the mountains maybe ya will need solar panels and a wind turbine and a generator !

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.

Gdetrailer wrote:

Save you money and put it into solar and a nice generator.. A 300W-400W windturbine is merely a decoration which will only net a couple of watts of power unless you are in a storm. A generator will charge up your batteries at a much faster pace and is far more reliable than wind power.

x2 for generator. Provides those charging amps day, night, rain or shine (or blizzard), etc. If it runs on the same fuel as your vehicle, the gas can for the generator is also an emergency reserve for the vehicle.

My mind is split on solar. It's a neat technology but the cons outweigh the pros in my mind.

Pros: quiet, rooftop install is always working if conditions are right

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.

Batteries need time to charge. Solar panels have the time most days so they are an effective charging method. We find a 100 watt panel and two batteries adequate to keep us going indefinitely. Just lights, fridge, fan, furnace. Another 100 watts would be required if we watched TV or used a microwave oven.

christopherglenn wrote:
Most of the wind turbines are in the 200-400 watt range, and while nowhere near as loud as an open frame generator, needing to be on top of a mast you can't hide it behind something. They also require a stiff breeze to do anything, and a moderate wind to be anywhere near peak output. Solar is about as loud as the wind blowing past the RV, and does nothing in the dark, shadows, and very little in the rain.

Small wind turbines typically are way over rated by the manufacturers. Typically they will not make ANY power below 7 MPH and the MIN windspeed to make a couple of milliamperes of current is around 10 MPH (the point where the turbine starts making power is called cut in speed). Typically they will not reach the "rated" output until you reach 20MPH-30MPH windspeeds, windspeeds above the max is the cut out speed, at that point the turbine will stop generating power and apply braking to prevent the blades from over speeding (bad things happen when the turbine blades go to fast).

I don't know about you but camping in a place where you have a constant 20mph - 30 MPH wind at 6 or 10 ft off the ground simply would not be fun at all. And I am not a fan of having a large potential cutting device spinning rapidly a few feet above my head..

Wind is fickle, comes and goes, shifts around and is not reliable.

Save you money and put it into solar and a nice generator.. A 300W-400W windturbine is merely a decoration which will only net a couple of watts of power unless you are in a storm. A generator will charge up your batteries at a much faster pace and is far more reliable than wind power.

Hi,

First find out how much energy you use. Create a battery bank to cover that energy for 3 to 5 days. Then design a solar system to recharge the bank.