Friday, January 22, 2010

Living With Wind and Solar

Can you estimate how your power production is split between wind and sun? Can you run a washer and dryer on wind and solar?


Julie and I do not have access to commercial electricity. The closest source is several miles away. We researched options, designed, installed and maintain a hybrid system that includes a one thousand watts solar array, a 400 watts wind generator and a seven thousand watts backup gasoline generator. The system operates on 24 volts with 900 amps of battery capacity and outputs 120 volts. The backup generator can output 240 volts but we have no need for this option at present.

We have almost every appliance that a family living in town might own -- refrigerator, washer, dryer, coffee maker, microwave, air circulation fans, furnace with a blower, curling iron, hair dryer, television, computer, electric blanket, air purifier, water pipe heat tape, radio/CD player, DVD player, Internet satellite modem, television satellite receiver, cordless phone, bedroom clock, electric toothbrush, hair clippers, rechargeable razor, outdoor lighting motion detector, battery tender for the motorcycle and power tools (table saw, drill, router, miter saw, etc). Also, we have a couple items that generally aren't found in town, a water pump and an appliance to provide household phone service via a cell phone.

The goal when living on wind and solar is to keep the system small and affordable but large enough to minimize running the backup generator. The main way to do this is through conservation, careful choice of appliances, meters to monitor output and usage, outlet strips and adapting usage to weather patterns. We use CFLs rather than incandescent or halogen lights. We read labels and evaluate energy consumption before buying appliances. We delay doing laundry if the weather is cloudy or we do laundry ahead of a weather forecast of cloudy weather. We also line dry, whenever practical.

Every appliance with a phantom load is plugged into an outlet strip. A phantom load relates to an appliance that uses electricity when turned off. Generally these are appliances with remote controls. For example, our satellite television receiver uses the same amount of energy when it's on or off. This is for convenience. When first powered on the receiver must download setup data from the satellite like a computer must boot up. By always being powered on the receiver can provide television instantly.

We have outlet strips on the television, satellite receiver, DVD player, radio/CD player, Internet satellite modem, wireless router, water pipe heat table and cell phone charger since the cell phone must always be connected to an antenna and a device called a Dock-N-Talk.

Kill A Watt Meter.
Kill A Watt Meter.


A device called a Kill A Watt meter measures usage for a single appliance. Plug the meter into an outlet and plug a device in the Kill A Watt to measure electricity usage. I use this device in conjunction with product labels. For example, three years ago Julie researched refrigerators and selected one that is larger than the refrigerator that came with the house but uses one-half the energy. We bought the refrigerator and gave the old one to a charity. I plugged the refrigerator into the Kill A Watt and checked the usage after two days. It used less energy than the label indicated. I attributed this to the fact that there are only two of us and no children opening the door frequently and leaving it open.

Recently Julie saw a bread machine on Craigslist and asked if I thought the system would support it. I wasn't certain but at a cost of only $10 we decided to purchase it. Yesterday Julie made the first loaf. The label rated the machine at 680 watts. During baking the meter peaked at about 480 watts for a short period of time. When the bread was finished the total usage was 250 watts. This is acceptable.

The bread machine illustrates another important consideration: learning and knowledge. Watt, amperage, voltage and some formulas must be understood. For example. A 100 watts light bulb turned on and forgotten for three hours will use 300 watts. A 900 watts microwave turned on for five minutes will use 75 watts (5 minutes divided by 60 minutes times 900 watts.) I'm as cautious about small loads as I am about short large loads like an 1,800 watts hair dryer.

OK, let's put the parts together.

We get six hours of good sunlight on most days. The solar array is 1000 watts at 24 volts so it can output 30 amps allowing for changing sun angle, friction and inefficiencies. Thirty amps times six hours will net 180 amps or about 4,500 watts. Thus, we can use about 4,500 watts each day. Sunlight before 9 AM and after 3 PM add a little more.

The wind generator is rated at 400 watts which means 400 watts in a consistent 28 MPH wind. What happens in a 6 MPH wind? Nothing. The start up speed is 7 MPH. At 10 MPH the generator will make about 25 watts. At about 35 MPH the generator will stop to prevent damage to itself.

Wind generators need to be high to get consistent winds. My tower is only 45 feet. It's not unusual to install a generator on a tower that costs three times as much as the generator.

What percentage of my electricity comes from wind? I estimate less than 10 percent. I don't have a meter on the wind generator to measure it. However, I do have meters that measure the solar array and total usage so I could read these meters, wait a month, read them again and subtract to get a close estimate of wind production. However, I've never done this. On windy nights the batteries hold even or charge some so I know the wind generator is supporting the refrigerator and other small night time needs.

Assuming we can generate about 4,500 watts daily then our consumption must be equal to or less than this to prevent running the backup generator. We can add up our usage by summing up each appliance's consumption averaged on a daily basis.

Air Purifier, 24 hours at 4 watts, 100 watts total
Electric Blanket, 1/2 hour at bedtime at 120 watts, 60 watts total
Water Pump, 6 minutes daily at 865 watts, 90 watts total
Clothes Dryer, 1/2 hour at 250 watts, 175 watts
etc, etc, etc

You'll notice some of the math isn't exact. For example, the propane clothes dryer users 250 watts to turn the drum but uses 750 watts periodically to ignite the propane.

We sometimes go two or three months without starting the backup generator so our usage is typically less than what the system can produce.

Two final items. We replaced our washer with a high efficiency washer that uses less electricity and less water and the refrigerator was replaced. These were winners. We replaced our kitchen range which had standing pilots with a range with more features that Julie found on Craigslist that has electric ignition rather than pilots. This was not a total winner. Unknown to us when we purchased it there is a difference between electric ignition and electronic ignition. Electric ignition has a glow plug in the oven which uses about 300 watts when the oven is on. An attempt to reduce propane usage resulted in an increase in electric usage while baking. We'll replace this range sometime in the future.

I've been doing construction on a utility room that necessitated moving the water pump and installing additional water lines. I'm using heat tapes until I finish the construction and get the external water lines properly insulated.

The cost of the system (utility building, solar array, wind generator, batteries, inverter, charge controller, breakers, enclosures, wiring and other components) was $12,000. Annual labor and the cost of maintenance of the system (distilled water for the batteries, gasoline, oil and filters for the backup generator) aren't significant. However, the cost of replacing the batteries will be significant. We paid $1,200 for the batteries five and one-half years ago. When it's time to replace them in a few years the cost will be more. Assuming a life of eight years the annual cost of the batteries will be $150.

What's the cost to us averaged over 20 years? I guesstimate about $85 per month. I plan on a few modifications and enhancements over the years to the net cost will be about $100 per month after these are included. But at the end of the 20 years the system will still have a long life expectancy with the exception of the batteries.

Eight-five dollars per month for electricity doesn't sound bad. But, in the hottest part of the summer when temperatures reach 100 degrees I think some people would be willing to pay more for air conditioning. With our system, AC isn't an option.

Would I connect to commercial electricity if it became available? No.

3 Comments:

Blogger THE Michael said...

If we were all forced to "farm" our own meat, vegies, and energy, I think we would naturally drastically reduce our usage of it all, since it does take more upfront money and labor. Plus, knowing where all this stuff is coming from makes you much more involved, and thus caring, about what you are using and why.

1/22/2010 06:54:00 PM  
Blogger MojoMan said...

Wow, Paul, that was an amazing answer to a simple question! Thanks.

I'm surprised and impressed that you have pretty much the same electric lifestyle as most (American) people. But then, you have a big-league system.

It would be enlightening if we all knew what our phantom loads are. It seems every time I turn around, we have some new gadget that has a little light glowing all the time.

I'll have to go back and read again: Do you have solar hot water? I understand that's one of the more cost-effective way to harvest solar energy.

1/29/2010 11:41:00 AM  
Blogger KingAzJay said...

Wow, quite a system, and very well thought out... maybe some day we'll leave our 12v lifestyle...

4/12/2010 09:19:00 PM  

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