Are MPPT Charge Controllers Really Worth the Cost?

From guest blogger Dale Marshall......

I would say that MPPT charge controllers are really worth the cost. The overall gain of harvesting more power with MPPT will make up for extra panels you would have to buy to make up for the losses. So far my gain has been around an average of 40%. I would have have had to spend twice the money to make up for those losses in extra harvesting power.

Once you get past the 250 watt mark MPPT is your best friend when it comes to power harvesting. I will give you an example. I have been doing some testing.

I used just 1 of my 125 watt panels. I used a regular PWM controller full sun, I was lucky to pull 4.3 amps. Voltage of course stayed at battery level. Max power at top charge charge was 14.4 volt at 4.27 amps. Rounded off math say 61.5 Watts, half of the panels rated output.

Now with MPPT I have a Solid 18 volts even coming in at 6.1 amps. MPPT Boost amps because it tracks voltage at VMP. But because of the way MPPT works I am getting a 14.4 volt charge at 7.5 amps at 109 watts. That's a gain of 3+ amps going into your battery bank. And it would take another 125 watt panel to make up for those losses. This is where MPPT shines like a star.

I hope this helps, take the time and weigh the cost. I do use a MPPT charge controller it is a Rouge MPT-3024. But there is other models out there. You just have to be careful on which ones to buy.

Everything You Need to Produce Your Own Solar Energy.....Check Out New World Solar Power!

Where Do You Start? With The Sunforce 60 Watt Solar Charging Kit

The Sunforce 60 Watt Solar Charging Kit gives you several more reasons to love the sun. It provides the power you need, while helping you save money and protect the environment. This kit is ideal for cabins, recreational vehicles, remote power, back up power, and 12 volt battery charging. It comes with everything you need to start producing up to 60 Watts, 4 Amps of clean, free power in all weather conditions.

Sunforce kits are easy to set up and operate.

Convenient Power That Helps You Save Money and Protect the Environment
The Sunforce 60 Watt Solar Charging Kit lets you harness the power of the sun, the most powerful and plentiful source of energy available to us. This inexhaustible supply of power is freely available wherever the sun shines, and gives users the freedom to power their homes, RVs, boats, batteries, and electronic equipment far from civilization or right in town. Solar power can help cut your energy bills by reducing your dependence on the main electrical grid, and can also provide back-up power during outages. Unlike nuclear and fossil fuels, solar power systems are clean and pollution free, and they require very little maintenance to operate.

Sunforce Solar Panels are effective in areas of both high and lower sun exposure, making them ideal for use in the United States. View Larger

Everything You Need to Power Up
The Sunforce 60 Watt Solar Charging Kit has everything you need to start generating power. It includes four - 15 Watt amorphous solar panels with durable mounting frames, a 200 Watt modified sine wave power inverter, a 7 Amp solar charge controller, and a wiring kit with accessories for easy installation.

With built in blocking diode technology, this solar charging kit is designed to protect against battery discharge at night. You can also use this kit to maintain the charge on any 12 Volt battery for clean, silent operation of various electronics, such as deer feeders and landscaping pumps. The included charge controller features a built in ultra bright blue LED charging indicator, and is a great choice for automobiles, recreational vehicles, tractors, all terrain vehicles, boats, electric fences, telemetry and more.

About Amorphous Solar Power
Amorphous solar panels are created by spraying silicon on to glass in very thin layers, and are commonly known as thin film solar panels. This process allows them to be better at generating electricity in all lighting conditions, including cloudy or shady environments. Sunforce amorphous solar panels are weatherproof and suitable for outdoor use. They have a maximum operating temperature range of -40 to 176-degrees Fahrenheit, require virtually no maintenance, and are also effective on cloudy days. They can even withstand impacts from one inch hailstones at 50 miles per hour.

Solar panels convert sunlight into an electric current, they do not store power. Sunforce Solar Charging Kits are primarily used to recharge 12 Volt batteries (not included), which store and provide usable power. The included 200 Watt power inverter allows you to use traditional 110 Volt appliances with this system. The included Sunforce 7 Amp Solar Charge Controller must be installed to prevent any connected batteries from overcharging. Once fully charged, it is normal for the charge controller LED to turn off and on as the battery voltage fluctuates from the discharge/recharge cycle.

Product Dimensions
Shipping Box: 41" x 13 1/4" x 16 1/4", 62.4 lbs
Individual Panel: 42.5" x 1.5" x 16", 11 lbs

Just Click Here to Order Your Own Sunforce 60 Watt Solar Charging Kit

Calculating the Voltage Drop on 12 Volt Systems

The greater wire resistance that you encounter, the greater voltage drop will incur. Besides that, the metal in the wire also plays its part in contributing to the voltage degradation. In order to allow lower voltages than the one supplied to the circuit for specific purposes within the device, voltage drop series circuits need to be used in direct and alternating current (DC and AC) devices. For instance, you would be having a device that comes with a 24 volt DC battery, an 18 volt motor, 3.4 volt lights and a 5 volt control logic chip, which all need a steady supply of voltages. All this calculation follows the principle of Kirchhoff’s Voltage Law, which mentioned that the summation of all voltages contains in a series of circuit, should be equal to zero.

What you need to do this project:
Calculator

Voltage Drop

Method:
Firstly, you need to gather all the necessary data in order for you to know certain information such as the amount of amps in the system, the length of wire in meters, the specific resistance for the wire’s metal in ohms*mm*mm/m, and the cross-section area in square mm.
You can use both specific resistance and the cross-section area as reference. However, the cross section can be calculated from the AWG rating by using a formula as described below:
Cross Section Area (in mm^2) = (((0.127 * 92 ^ ((36 – AWG) / 39)) / 2) ^ 2) * pi

You can also input your data by using the following formula:
Voltage Drop = Amps * (2 * Length of Wire * Specific Resistance / Cross Section Area)

In the formula given above, the number “2″ is representing the accounting for the electricity’s return trip meaning that it doubles the length of the wire. For instance, you are having a 16 AWG copper wire that runs up to 20 meters along with one amp. You need to reference a specific resistance for this kind of copper at 0.01785 ohm*mm*mm/m with a cross-section diameter of at least 1.3 mm*mm. The sample calculation is as follow:

Voltage Drop = 1 * (2 * 20 * 0.01785 / 1.3)

Voltage Drop = 1 * (0.714 / 1.3)

Voltage Drop = 0.549

Once you have done the calculation, you would be able to compare the above figure against the original voltage of 12 volt in order for you to see the percentage drop. The comparison calculation for the percentage drop is as follows:
Percentage of Voltage Drop = Voltage Drop / Original Voltage * 100

Percentage of Voltage Drop = 0.549 / 12 * 100

Percentage of Voltage Drop = 4.58%

Whenever you are using high impedance resistor voltage drop circuits you would be able to conserve power. However, if you install resistors, which are too low of its overall circuit ohm value, will result to more flowing of your current usage thus creating the possibility of smoking or burning of your electronic components.

Posted courtesy of Do It Yourself Guides


Everything You Need to Produce Your Own Solar Energy.....Check Out New World Solar Power!