Solar Panel Array: Number of Panels Needed
 |
| Solar-powered bahay kubo (original photo from: Hagikhikan) |
Before proceeding with cost savings and payback calculations, let us discuss some important topics such as solar panel sizing, electrical loads and Ohm’s Law which is the basic formula that we are going to use.
In its simplest form, Ohm's law states that the current in an electrical circuit is directly proportional to the applied voltage and the resistance of the circuit. The three (3) most common mathematical expressions are:
P= V * I I = P / V V = P / I = I * R
Where:
P = Power : the product of the voltage times the current in an electrical circuit measured in watts
V= Voltage : the electromotive force (pressure) applied to an electrical circuit measured in volts
I = Current : the flow of electrons in an electrical circuit measured in amperes
R = Resistance : the opposition to the flow of electrons in an electrical circuit measured in ohms
Example Only: ( Based on a daily usage)
LOAD DESCRIPTION RATING HOURS WATT-HRS.
_____________________________________________________
LAPTOP 75 watts 4 300
LIGHTING (4x15-watt CFL) 60 watts 5 300
ELECTRIC FAN 120 watts 6 720
TELEVISION 100 watts 6 600
REFRIGERATOR (35% run-time) 120 watts 8 960
TOTAL DAILY WATT-HOURS REQUIRED = 2,88O WATT-HOURS
In the Philippines which is a tropical country and has plenty of sunshine we can get at least 8 to 10 hours of daily sunshine. Use 5 hours daily average sunlight for mid-latitude in the US.
NUMBER OF SOLAR PANELS NEEDED:
Although I used a 45-watt panel for my experiment last year, I recommend using a 100-watt solar panel currently available at Home Depot as of this writing, at $199.00 each with free shipping within the US except GU, PR and VI. This is the Grape Solar 100-Watt Monocrystalline PV Solar Panel. This is a whole lot cheaper and more efficient. I got mine on sale last year for $149.99 from Harbor Freight Tools and their regular price is $299.99. You will need two of these, as compared to one from Home Depot, and still you are 10 watts below capacity. Let's stick to our example load description for computational purposes, as follows:
 |
| Grape Solar 100-Watt Monocrystalline PV Solar Panel |
Using a 100-watt solar panel and assuming 8 hours of sunshine, that would give us 800 watt-hours per day per panel.
Total number of solar panels = 2,880 watt-hours/800 watt-hours per day = 3.6 = approx. 4
Therefore, use: 4 solar panels with a capacity of 100 watts each.
Based on our example daily load requirements, our total solar panel cost would be:
Total solar panel cost = 4 panels x $200.00 = $800.00 + tax
This cost does not include the DC batteries needed for storing solar energy during night time and extreme weather conditions without sunlight. The inverter needed to convert DC power to AC power (power coming out from your regular power/lighting outlets) is also not yet included in our cost.
Basically, if you live in the rural areas and just need power for electric fans, some lighting at night and some juice for charging your I-pads, I-phones, notebooks and other portable devices, all you really need is a 100-watt solar panel and a solar charge controller which usually come free with the kit. Otherwise, you can buy the controller below $20.00 from Amazon.com. Connect your solar panel in parallel with wind turbine and your electrical needs 24/7, 365 days a year, are all set. You don’t have to worry about brown-outs anymore.
Every year the cost of solar panels are going down and the designs are becoming more efficient brought about by technology advances. Direct savings is realized if you actually connect your DC appliances and other DC power requirements directly to the solar charge controller and you’re off-grid, meaning not connected to any utility power company. That means all your appliances and light bulbs should be rated either 12-volt DC or 24-volt DC. The solar panel can generate as high as 27.8 - 29.5 volts DC, that’s why you need a charge controller to regulate the voltage at either 12 or 24 volts depending upon your needs.
This is just a bird’s eye view of how much is involved in owning solar panels. If you really need to know how much it would cost you to have solar panels installed in your homes, it would need an in-depth analysis of your actual monthly electric usage for a period of 12 months, and also actual survey of your house location to determine the best location and efficient utilization of your solar power system.
For a more detailed information, take a look at Wall Street Journal’s study on the economics of installing residential solar in 5 US cities.
What I can say right now, with the government incentives and rebates, as well as lease options being offered by companies such as SolarCity, SunPower Corporation and other solar companies, there is no better time than now, to start using solar energy. Right now, you don’t have to shell out $20,000 - $30,000 as initial investment for your solar panel system. Instead, you just pay for usage of the solar panels which are owned by the solar companies. You will have considerable savings and significantly lower monthly payments than your electric bills from your current utility providers. Utility companies bill you for transmission and distribution charges which will be eliminated when you use solar. Another advantage is helping your environment to become free from pollution caused by diesel and fossil-fuel generating power plants.
Is it not a good legacy for our grandchildren and their children in the future to have a pollution free environment?
No comments:
Post a Comment