My parents need some sort of backup power at their home on the coast, this weekend the power went out and the sump pump in the basement went out as well, thus when they went down stairs they found 2 inches of water flowing from the open dirt basement, through the door and into the garage, flowing out of the garage door. they were not the least bit happy and decided they want a backup system. They were originally thinking of a cheap 1000 watt generator but I suggested a wind generater because it would run of a free resource (wind) which we have a surplus of on the coast.
so what do you guys think of these models?
http://www.costco.com/Browse/Product.aspx?Prodid=11173498&whse=BC&Ne=4000000&eCat=BC|114|3241|57032&N=4018034&Mo=1&pos=5&No=1&Nr=P_CatalogName:BC&cat=57032&Ns=P_Price|1||P_SignDesc1&lang=en-US&Sp=C&ec=BC-EC10617-Cat3241&topnav=
http://www.costco.com/Browse/Product.aspx?Prodid=11173181&whse=BC&Ne=4000000&eCat=BC|114|3241|57032&N=4018034&Mo=1&pos=5&No=0&Nr=P_CatalogName:BC&cat=57032&Ns=P_Price|1||P_SignDesc1&lang=en-US&Sp=C&ec=BC-EC10617-Cat3241&topnav=
I am leaning toward the higher wattage model to hook up a bank of marine batteries. They need this to be able to work the sump pump, fridge/freezer, wood pelet stove, lights at night and the occasional tv if possible. THey usually have the power go out 2-3 times a year for a few days at a time and 2 years ago they didnt get power for over a week.
Let’s look first at the electrical devices that are wanting to be operated.
What is the sump pump wattage? A low estimate for a 120v model might be 120 watts. I saw a 12v backup model that draws 240 watts and is charged from house current while city electricity is on. The cost is about $400.00.
What is the wattage of the refrigerator? A basic modern refrigerator compressor will draw approximately 2 amps (240 watts) while running. During defrost cycles the wattage will be approximately 400 to 800 watts for approximately 20-30 minutes two to four times a day. During start-up, the compressor will draw 4 to 10 times the amperage before it is up to speed. During compressor start-up the wattage will climb to approximately 2,400 watts. If the refrigerator is an expensive side-by-side, the wattage draw will likely be considerably higher.
How many lights are to be used? What is the wattage of each bulb? Two each 60 watt light bulbs will draw 120 watts. Two hours of 120 watts is 240 watt hours.
What is the wattage of the television? A typical modern television will draw approximately 15 watts while turned off, and use approximately 180 to 240 watts while on. Two hours of watching television would consume approximately 480 watt-hours.
What it the wattage of the pellet burner? I have not seen a pellet motor before, but I suspect that the wattage ought to be reasonably low, perhaps 60 watts.
To power the refrigerator, sump pump, two light bulbs, the television, and the pellet burner for two hours, the system would have to be able to provide approximately 1,000 to 2,000 watt-hours each hour in use. Using 12v storage batteries, the amperage draw would be approximately 83 to 167 amps. In a best case scenario with an eye for dependability and long life of the storage batteries, the maximum draw from each battery would be kept at or below 20 amps. Five to ten storage batteries would be needed to provide electricity and overcome efficiency losses in an inverter
for one hour. For each additional hour, the battery bank must be doubled. If the city power is off for three hours, then there will be needed approximately 15 to 30 storage batteries.
Storage batteries require at least about 2 amps input to charge well. For a one hour backup battery bank, the charge rate needs to be approximately 10 to 20 amps. For a three hour backup, approximately 30 to 60 amps are needed to charge the batteries.
The Air 400 wind generators are rated at a maximum of 400 watts with 27 amps in a 26 mph wind. The maximum output will likely not be achieved beyond once or twice a year, and for no more than perhaps a few seconds. Expected output would remain within the 1 to 5 amp range during normal breezy days.
I used two of the 300 watt Air wind generators for two years on my property. (Taken from a homesteading book I wrote several years back): “The total output of the two generators combined was under 1000 ampere hours for the full three months of the first summer, less than what one PV panel puts out in two weeks. A gasoline generator could have produced the same output with 2 gallons of gas. The cost was over twice as much as PVs and produced one sixth of the power.”
My Air 300s were mounted on a hill that got an almost constant wind. The Airs that I owned were extremely undependable, the advertised ratings were half of the actual output, the noise level in high winds sounded like a prop airplane taking off, and there was absolutely nothing good about the wind generators.
In my opinion there is little or no chance whatsoever of the Air model providing the needed electricity to power the appliances mentioned. It is of course possible to mount 50 Air wind generators along with 50 storage batteries and hope that city power does not go down for more than an hour or two, but a gasoline generator would work much better and do it for about $40,000.00 less.
Now if the home owner were to switch to 12v DC appliances, the same devices could be operated every day of the year with about 3-5 PV panels (depending on the amount of sunlight in the region). The reason that the backup system costs so much for the 120v AC appliances is because the appliances waste electricity worse than a 4 mpg car wastes gasoline.
If a battery backup system is necessary, why not just charge the batteries with the available 120v AC house current? For a 3 hour backup during stable 26 mph winds that do not change speed or direction, and in a universe where everything is idyllic and perfect, the house would need approximately 12 Air-400 wind generators to power the few appliances.
Now let’s go back to the original question about powering the house for up to two weeks, which is 336 hours. 336 hours times 1,000 to 2,000 watts needed per hour equals about 336,000 to 672,000 watt-hours needed. 336 times the approximately $40,000.00 needed for one hour, sums to around $13,440,000.00. Yep, I’d like to be the guy making the commission off that sale!
Yea, a gasoline or diesel generator is sounding pretty good right about now, huh?
But the generator must be no smaller than 4,000 watts so that it can start the refrigerator as well as run at under half the rating so as to maximize dependability. The user also needs to remember to unplug everything from the generator before it runs out of fuel or else the generator wiring will burn-out.
