"He Didn't Build That" I Did...(Part 3)

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?

"He Didn't Build That" I Did... (Part 2)

My finished tool/storage shed with solar panel on the right side

How To Install A Solar Panel

Before proceeding to our topic of installing solar panel, let me give you a brief introduction about solar panels and their types.

A solar panel (also solar module, photovoltaic module or photovoltaic panel) is a packaged connected assembly of photovoltaic cells. The solar panel can be used as a component of a larger photovoltaic system to generate and supply electricity in commercial and residential applications. Each panel is rated by its DC output power under standard test conditions, and typically ranges from 100 to 320 watts. The efficiency of a panel determines the area of a panel given the same rated output - an 8% efficient 230 watt panel will have twice the area of a 16% efficient 230 watt panel. Because a single solar panel can produce only a limited amount of power, most installations contain multiple panels. A photovoltaic system typically includes an array of solar panels, an inverter, and sometimes a battery and or solar tracker and interconnection wiring.

A solar panel or photovoltaic module, is composed of individual PV cells. This crystalline-silicon panel has an aluminium frame and glass on the front.

A solar cell (also called a photovoltaic cell) is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect. It is a form of photoelectric cell (in that its electrical characteristics-- e.g. current, voltage, or resistance-- vary when light is incident upon it) which, when exposed to light, can generate and support an electric current without being attached to any external voltage source. (Source: Wikipedia)

Types of Solar Panels:

1. Monocrystalline silicon (mono-silicon or single silicon) - the most efficient type of solar panels. They convert sunlight into more electricity than the other types below. As a result of their high silicon content, they’re also more expensive, but you need fewer of them. That’s the reason why they’re ideal for roofs, because fewer solar panels means lesser load bearing weight.

2. Polycrystalline silicon (multicrystalline or multi-silicon) - have lower silicon levels than “mono” panels. In general, that makes them less expensive to produce, but they’re also slightly less efficient. Their overall construction design can often make up for the efficiency loss, so they’re also good for roofs.

3. Amorphous silicon (thin film) - inexpensive to make and can absorb sunlight even on a cloudy or rainy day, but not efficient as compared to the first two above. They are usually installed on ground structures and not on roofs. This is the type of solar panel that we are going to install.

There are two more types of solar panels: BIPV (building integrated photovoltaics) and solar hot water (thermal) panels. BIPV’s look like real roofing tiles such as solar shingles. They have good aesthetic looks, but good looks cost a lot more. Also, they are less efficient than conventional PV.

Now that we're done with the crash course on solar panels, let's get down to business.

Tools You Need:

1. Electrical Pliers/Wire Cutter
2. Flat Head and Phillips Screwdrivers
3. Electric Drill/Screwdriver (optional)
4. Wire Stripper/Terminal Crimping Tool - this is a must have tool if you are a novice

Schematic/Wiring Diagram:

Wiring diagram from solar panel to junction box

The solar panel kit comes in 3 pieces, rated at 15 watts each for a total of 45 watts with its own connecting wires, 20 feet in length (gauge #16). This is good for short distance only from solar panel to solar controller/voltage regulator because as you go farther, there is a higher voltage drop along the wires. Here is what you need to do to minimize voltage drop:

1. Cut/splice the wires to desired length using wire cutter/splicer.

2. Connect positive to positive (red wires) and negative to negative (black wires).

3. Attach the connected wires to wire connectors/terminal block and place them inside a PVC junction box.

4. Use an insulated 3-wire extension chord (gauge #12), usually comes in standard 25-foot and 50-foot length, and cut to desired length from the PVC junction box to the location of the solar controller/voltage regulator.

5. Connect the positive wire (red) from the junction box terminal to the positive terminal of the solar controller/voltage regulator. Then connect the negative wire (black) to the negative wire (black) of the same component.

6. Use gauge #4 wire, 3 feet in length for connecting the solar controller/voltage regulator to 12-volt DC battery and from battery to inverter (see wiring diagram). Make sure the positive wires and negative wires do not touch each other, as this will cause short circuit causing damage to your expensive components, especially the inverter.

The color of the wires vary depending upon the source or manufacturer, so pay close attention to what kind of terminal you connect the wires to. Simple rule is: positive to positive and negative to negative. I can't emphasize well enough about this simple rule, but this is very important.

Before starting any of the above instructions, make sure you cover the solar panels first to prevent electricity from flowing through the wires while you are working, and to prevent damage to solar panels just in case the wires accidentally come in contact with each other.

The inverter (left side) which converts DC to AC power is connected to two 12-volt deep cycle lead acid battery (2nd battery not yet connected) with a rating of 105 amphours. The battery is connected to the solar charge controller or voltage regulator that came with the kit, as well as two light bulbs. 

On the left side is a 1000-watt pure sine wave inverter which I bought from Amazon.com and on the right side is a 7-amp solar charge controller that came with the kit. As you can see the output voltage is 12.5 volts DC. 

The front panel of the solar charge controller is equipped with USB port and three other ports (6-volt, 9-volt, 12-volt) for charging cell phones, laptops, car battery and other portable DC devices. You only need a 300-watt inverter for this particular set-up, but I opted for a higher output size for future use, as I plan to install more solar panels in the near future.

There you go folks, you have just learned how easy it is to install a solar panel. Maybe next time, we can build the solar panels ourselves from new or recycled solar cells. You will be surprised how easy and simple it is to build one.

Next time I will cover cost benefits and payback calculations of solar panels based on my experiment. Hope I shed some light on this topic, as I tried to discuss this in layman's terms as much as I could. If you have some questions, you can post them under the comments section of this article below.

"He Didn't Build That" I Did... (Part 1)

How I built my solar-powered shed:

Solar-powered Shed

I built this shed, (12 ft. x 10 ft.) 3 years ago for storage purposes and to keep my power tools in a safe and convenient place. I installed solar panel for observation and experimental purposes and to provide the much needed electricity for my toys: CB radio, small TV, Hi-Fi stereo, ceiling fan and for charging my cell phone. It also provided power for my Koi pond's waterfall pump and filter.

If you are interested in building a similar one for storage purposes and for any purpose you may want, here is how I did it:

1. First find a convenient area in your backyard or sideyard (whichever is convenient for you), and make sure you level the ground where you are going to put your floor slab.

2. For this size which is 120 square ft. (12 feet long and 10 feet wide), I used 3 pcs. 4"x4"x12' lumber, each of which is placed on top of 4 pcs. concrete hollow blocks to prevent the wood in direct contact with the ground. I also sealed and cured them before hand prior to installation. You can also use 4" thick concrete slab for your flooring foundation, it's up to you.

3. Then I placed on top of them, a 2"x6"x10' floor joists spaced 16 inches apart and across the 4"x4" floor slabs. After that, you nail down your flooring. You can use a 5/8" plywood or MDF. I just used a 1/2" MDF which is a lot cheaper, available from your local Lowe's or Home Depot.

4. By the way I'm doing this myself and before I knew it, I forgot to take pictures of the initial stages of my construction, so don't get confused. Just follow the procedure as numbered. After laying down and finishing the floor, start framing the wall studs. You can just use three studs per 4"x8" std. size MDF, but in my case I followed the CA building code of 16 inches between studs, i.e. 4 pcs. of 2"x4"x8' per std. size MDF.

5. Next step is to install the rafters for the roof. At this point, I needed some assistance because it's hard to do this part on your own. Spacing is 2 ft. between each rafters.

6. After all the rafters are in place, nail down the MDF board in place. Staple the #15 black felt roof deck protection as shown in picture, and then install metal flashing to protect roof from water damage. 

7. Next nail down asphalt roofing shingles (different styles and colors) of your choice, in an overlapping manner and in alternating positions (as in laying down concrete hollow-blocks).

8. Nail down MDF wall boards and ceiling vents (optional).

9. Install doors and windows and any decorative wall finish of your liking. There you go, you have completed building a wooden storage shed. Now, it's up to you if you want to paint it or leave it as is. I recommend that you paint your completed project with matching color with your house to give it a more aesthetic look, and to protect it from early wear and tear brought about by the harsh environment.

Next time, I am going to discuss how I installed the solar panel (as shown above), and how much it cost me to install one.