Q: How to calculate the wattage of my house/farm from the hydro bill?
A: Usually 60 days for the bill cycle, 24 hours per day, let's say you paid for 1700 KWH, the mean KW is 1700/60/24=1.18kW, so you need roughly 2KW for you house/farm.
If you want to have your air conditioner, dryer, washer, fridge, ceiling fans, water pump, microwave ovens or other appliances with inductive loads inside connected with off-grid wind turbine, the start-up current of these appliances are 5 to 7 times bigger than the running current for about 2 minutes, these appliances request more power to start, it is critical for off-grid wind turbines, so you if choose off-grid wind turbines, you choose from 10KW, to make sure these appliances will work properly.
If you choose on-grid wind turbine, you can get the excessive power you request from the grid, you can choose from 2KW to 10KW wind turbine according to your budget.

Q: If I need 5KW for my house, do I choose a 5KW wind turbine?
A: You need to check the mean wind speed of your area, and the tower height, terrain, location of the wind turbine will dramatically affect the yield of the wind turbine. See the Related Topics on the left side, find the mean wind speed for your house/farm. Then you check the rated wind speed for the wind turbine, for 5KW, it is 10m/s, or 36km/h or 22.5mph.
If you have the mean wind speed larger than 10m/s, you get the full 5KW from the wind turbine.
If you have the mean wind speed 7m/s, you get roughly 5KW*75%=3.75KW from the wind turbine, you can choose a bigger wind turbine according to your budget.
If you have the mean wind speed less 2m/s, the wind turbine is not your choice, you might consider solar pwer.
You can choose to use solar power with your wind turbine, or on-grid wind turbine to get a fully coverage of your electricity consumption.

Q: What if can use both wind turbine and solar power in my area?
A: Because the solar panel is more expensive than wind turbine, so you should use as more wind as possible. For wind speed less than 4m/s (14.5m/h or 9mph), 90% solar and 10% wind; for wind speed more than 4m/s (14.5km/h or 9mph) but less than 5.4m/s (19.3km/h or 12 mph), 50% solar and 50% wind; for wind speed more than 5.4m/s (19.3km/h or 12mph), 30% solar and 70% wind.

Q: What is islanding?
A: The first safety issue that comes to everyone's mind for samll customer-sited systems is a condition called ISLANDING. Islanding is where a portion of the utility system that contains both loads and a generation source is isolated from the remainder of the utility system but remains energised. When this happens with a distributed power system, it is referred to as supported islanding. The safety concern is that if the utility power goes down (perhaps in the event of a major storm), a distributed generation system could continue to unintentionally supply power to a local area. While a utility can be sure that all of its own generation sources are either shut down or isolated from the area that needs work, an island created by a residential system can be out of their control.
There are a number of potentially undesirable results of islanding. The principal concern is that a utility
line worker will come into contact with a line that is unexpectedly energised. Although line workers are
trained to test all lines before working on them, and to either treat lines as live or ground them on both
sides of the section on which they are working, this does not remove all safety concerns because there is a risk when these practices are not universally followed.
Fortunately, static inverter technology developed for grid-interactive systems is now specifically designed
so that there is practically no chance of an undesired supported island stemming from an interconnected
residential or small commercial systems. This feature is referred to as anti-islanding. Grid-tied inverters
monitor the utility line and cease to deliver power to the grid as quickly as necessary in the event that
abnormalities occur on the utility system. Such performance requirement is generally described in both
the inverter and the interconnection standards.

Q: What is manual disconnect?
A: An external manual lockable disconnect switch ("manual disconnect") in the interconnection context is a switch external to a building that can disconnect the generation source from the utility line. The
requirement for a manual disconnect, stems from utility safe working practices that require disconnecting
all sources of power before proceeding with certain types of line repair.
Whether a manual disconnect for small systems, such as photovoltaic (PV) systems, using certified
inverters should be required has been the source of considerable debate. In strict safety terms, a manual disconnect is not necessary for most modern systems because of the inverter’s built-in automatic
disconnect features as discussed in the previous section. Both the Canadian Electrical Code (CE Code) and the National Electrical Code (NEC) in the United States, refers to the need for an additional switch that is (1) external to the building, (2) lockable by utility personnel, and (3) offers a visible-break isolation from the grid. As such, a manual disconnect is an additional means of preventing an islanding situation. And, the key from the utility perspective is that the switch is accessible to utility personnel in the event of a power disruption when utility line workers are working on proximate distribution system lines. In addition, in many situations, utility line workers can provide redundant protection against islanding by removing a customer’s meter from the meter socket. Still, many utilities require a separate, external manual disconnect.
While the cost of installing such a switch is not large relative to the overall cost of a micropower system, a PV system for example, when compared to expected energy savings from the system, such a switch is
relatively expensive. Also, for systems located on the top of tall buildings, such a switch becomes very
expensive. In the USA, some state-level net metering and interconnection rules require that the utility pay for the installation of a manual disconnect. In New Mexico, use of the meter is an optional alternative to a separate switch while in many other states a manual disconnect is not required, at least for small systems; that is the case of California, New Jersey, Washington, and Nevada. Also, some utilities, such as those owned by the New England Electric System, have established their own interconnection guidelines that do not require an external manual disconnect for small systems.