http://www.sentex.net/~sxing/tractor_faq.htm

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 1.18 * 1.2 = 1.42kw， so 2KW is model for your house/farm, 1.2 is the factor we use for this calculation

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 2kw * 3 = 6kw and up, to make sure these appliances will work properly

the actual yield of the wind turbine depends on the wind speed in your area

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 in according to your budget.

If you have equipment that is labeled as BTU, not kw

Btu(British thermal unit) is a measure of energy while kw is a measure of power. Use the following for conversion.

10000 Btu/hour = 2.93 kw
1000 Btu/minute = 17. 58 kw
1 Btu/second = 1.055 kw

1 hp = 1.341kw

Q: How many batteries I need for my wind turbines?

A: The batteries you need depends on the hours that need to use per day, let us assume that,

you use 6 hours per day,

the capacity of wind turbine is 5000w,

the DC output voltage for the controller is 240Vdc

the unit battery capacity will be 5000W x 6H x 1.67 / 240V = 208.75 AH or bigger, 1.67 is the factor we use for the calculation

if you use 300 AH 12V batteries, you need 240V/12V = 20 units


Q: Where can I find the chart for the wind speed and wing turbine yield?

A: We have these charts, vertical 200w to 5KW, 10KW to 30KW, horizontal 200w to 20KW in word file.


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

If the wind speed for your area is more than

3m/s or 10.8km/h or 6.75mph for more than 3000 hours annually, congratulations, you can enjoy the savings to use our wind turbines,

if not, please check our solar panels if you have enough sun shine.

wind speed in Canada

wind speed in USA or this link city data by US cities

then you check the rated wind speed for the wind turbine, for 5KW, it is 10m/s, or 36km/h or 22.5mph, you can find the wind speed requirements from here

if you have the mean wind speed bigger than 10m/s, your get the full 5KW from the wind turbine

if you have the mean wind speed 7m/s, you get roughly 5KW x 75% = 3.75KW from wind turbine, you can choose a bigger wind turbine in according to your budget

if you have the mean wind speed less than 2m/s, the wind turbine is not your choice, you may consider solar power

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: How to convert m/s to KM/H or MPH?

A: 1m/s = 3.6 KM/H = 2.25 MPH


Q: What is the pros and cons of vertical wind turbines?

A: Vertical wind turbines are more efficient than horizontal wind turbines(up to 18%), bigger capacity(up to 3 Mw), lower start up wind speed(2.5m/s or 9km/h or 5.6 mph), higher survival wind speed( 60m/s or 216km/h or 135mph), silent, never twist the wires/cables up, but more expensive.


Q: Do you have CE for your wind turbines?

A: Yes, we have CE for our horizontal wind turbines up to 20kw,

for on-grid inverters, we have CE for up to 6kw


Q: What if I 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 (14.5km/h or 9mph), 90% solar, 10% wind

for wind speed more than 4m/s (14.5km/h or 9mph) but less than 5.36m/s (19.3km/h or 12mph), 50% solar, 50% wind

for wind speed more than 5.36m/s (19.3km/h or 12mph), 30% solar, 70% wind


Q: grid tied inverters for solar and wind

A: Xantrex CSA UL for solar 3.8kw about $2700

SMA Sunny Boy UL for solar 6kw about $4000

SMA Windy Boy UL for wind generator 1800U 1.8kw US$2600, 2500U 2.5kw US$3000, 3800U 3.8kw US$3425, and 6000U 6kw 240vac about US$5750

Beacon UL CEC NYPSC for solar 5kw about $6800

Fronius for solar 5.1kw 240vac about $3500

SW swries 5.5kw 120vac $2800 Xantrex Grid Tie Interface GTI $430

Outback power for solar 3.6kw about $1800

If you need the capacity bigger than 6kw, you can couple two 6kw inverters.


Q: Where I can find The Database of State Incentives for Renewable Energy (DSIRE)?

A: http://www.dsireusa.org/

Q: What is world voltage?

A: http://www.kropla.com/electric2.htm

Q: What is islanding?

A: The first safety issue that comes to everyone¡¯s mind for small 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.


Q: What is three phase?

A: Check wikipedia answer here.


Q: What is single phase?

A: Check wikipedia answer here.

Q: wind speed and wind pressure

A:

The wind pressure can be approximated by: Pressure = ?x (density of air) x (wind speed)2 x (shape factor)

* The density of air is about 1.25 kg/m3.
* The shape factor (drag coefficient) depends on the shape of the body. It has order of magnitude 1 and is dimension less.
* The wind speed must be expressed in m/s. In that case the pressure has units kg/m/s2, i.e. N/m2.

See this table:

Bft

Wind speed (m/s)

Wind pressure (N/m2)

Lower limit

Upper limit

Upper limit
0

0.0

0.2

0.03
1

0.3

1.5

1.4
2

1.6

3.3

6.8
3

3.4

5.4

18
4

5.5

7.9

39
5

8.0

10.7

72
6

10.8

13.8

119
7

13.9

17.1

183
8

17.2

20.7

268
9

20.8

24.4

372
10

24.5

28.4

504
11

28.5

32.5

660
12

32.6

> 660


Q: Height and wind speed

A:
Wind speed (m/s)
Height (m) Neutral Unstable Stable
1.0 1.8 1.9 1.7
1.5 2.3 2.4 2.2
2.0 2.7 2.9 2.6
3.0 3.3 3.4 3.2
4.0 3.7 3.8 3.6
4.8 4.0 4.1 3.9
7.1 4.5 4.6 4.5
10 5.0 5.0 5.0
15 5.5 5.4 5.6
21 6.1 5.8 6.3
29 6.5 6.1 6.9
42 7.0 6.5 7.7
60 7.5 6.8 8.6
88 8.1 7.1 9.8
117 8.5 7.3 10.9


The IEEE and UL guidelines for the wind turbines:

IEEE 519 - 1992 are recommended practices and requirements for the harmonic control of electrical power systems. It sets maximum total harmonic distortion (THD) limits on voltages and currents that a power system is allowed. Therefore, the PCS cannot inject harmonics into the grid that cause the system to go above these limits set forth by the standard and the PCS should filter these harmonics [23].

IEEE 929 - 2000 are recommended practices for the utility interface of photovoltaic (PV) systems. Though written for PV inverters, the guidelines and specifications can be adapted to be used for an inverter connecting a DER to the utility.

IEEE 1547 - 2003 is the standard for the interconnection of distributed resources to the utility grid. This standard outlines requirements and specifications that the conversion systems of the DER have to meet to be allowed to connect to the utility. This standard does not deal with the concepts and issues of intentional islanding, and currently dictates that the DER shall disconnect from the distribution system when islanding events occur. As noted above the standard does leave open a section for consideration of intentional islanding in future revisions of the standard. An analysis of 1547 raising questions to issues proposed by it can be found in [24].

UL 1741 is the Underwriters Laboratories' testing standards for equipment as they relate to IEEE 1547.