Choosing a Power Generation Method

There are several power generation methods available these days.  The most common are Solar and Wind.  There are also other methods, including wood gas powered generators (by heating wood in a controlled environment, a gas is given off that can run a gas powered generator), Thermocouple (a method which converts a temperature gradient into electricity), Steam Powered Generators, and others which I will talk about in more detail in later articles.  For this article, I will focus on Solar and Wind power generation.

Choosing the right power generation method for your situation can be difficult.  There are a few things to consider when doing this.  The most important is where you live or plan to setup your power generator.

Solar Panels

For Solar, you will want to find out just how much actual sunshine your site receives in a year.  This will vary dramatically from one location to another.  There are charts available on the internet to help you with this, but if you cannot find one for your area, you might want to check with your local weather station as they generally keep these facts along with other historical weather data. 

 Also, you will need to take into account the seasons of the year.  If you live in an area as far north as I do, you will find that the summer days can last as long as 18 hours and the winter days can be as short as 6 hours.  If you live in an area closer to the equator, the seasonal changes will not be as noticeable.  An interesting thing about Solar panels is that they produce more power when the temperatures are colder rather than warmer and if you receive a lot of snow during the winter, you can usually count on the sunlight reflecting off the snow to boost power output.  Where I live, I have found that the colder temperatures during the winter along with the reflectiveness of the snow can almost make up for the shorter daylight hours.  Once you know how much power per month you will need, you can do a little math to calculate how big of a solar array you will need.  For example, if you require 300 Kw/h per month and you receive an average of 12 hours per day of good sunlight, you can use the following formula to calculate the array size.

 (Hours of Sun per Day X 30) / Monthly Power Requirement = Array Size in Kilowatts

 Or

 (12 X 30) / 300 = 1.2 (1.2 Kw or 1200 watts)

As I mentioned in a previous article, you cannot count on ideal situations, like 12 hours of good sunlight every day.  It is a good plan to double the amount you will be generating (1200 watts to 2400 watts).  Better to have the capability to produce more than you need, rather than not enough.

Wind Farm

For Wind, most of the same facts apply as for Solar.  You can check wind charts to find out what the average wind speeds are in your area.  You can calculate the size of the Wind Farm you will need based on average wind speeds. 

 One thing to know about purchasing Wind Generators is that they are usually rated in a wattage based on a specific wind speed.  You will have to account for this in your calculations.  For example, if a Wind Generator’s Specs Sheet say it will generate 400 watts at a wind speed of 50 KM/hour (30 MPH), but your average wind speed is 25 KM/hour (15 MPH) you will only be able to count on a portion of the 400 watts.  Most Wind Generator Spec Sheets will show a graph of the power output based on wind speed.  You will have to match power output to your average wind speed.  You can use the formula below to figure out how many Wind Generators you will need.

 ((Monthly Power Requirement X 1000 (to convert to watts)) / (30 days X 24 (24 hours per day))) / Wind Generator Output in watts (based on average Wind Speed and output wattage at that speed) = Number of Wind Generators

 Or

((300 X 1000) / (30 X 24)) / 100 = 4.1666666667 (4 Generators putting out an average of 100 watts)

As with Solar, you cannot count on ideal situations, like 24 hours of the expected average wind speed will hold true every day.  It is a good plan to double the amount you will be generating (4 to 8 generators).  Better to have the capability to produce more than you need, rather than not enough.

Solar and Wind Hybrid

You can also consider combining both Solar and Wind to create a Hybrid System.  Simply split the generating requirements and use both.

As for costs, you will find Wind Generators will be more cost effective as long as you have the wind available to run them.  Solar panels have come down in price a lot in recent years and are expected to drop even more now that a number of manufactures are sitting on large inventories.  Over all, I have found that Solar panels are more reliable as they have no moving parts and most are warrantied for at least 20 years.

My Next Article will be on choosing the Right Inverter for your requirements.

Posted in Power Production | 14 Comments