Do It Yourself Solar Energy Projects: DC

Showing posts with label DC. Show all posts

Friday, May 18, 2012

Let's Put Your Starter Solar System Together

The most common first step in learning to create your own solar energy is buying one of the widely distributed "solar panels kits". And that's great, nothing has done more for helping the newcomer get started then to walk into a Harbor Freight store or Costco and buy a ready to set up kit.

But like any sport or hobby a large percentage of these kits get put into the closet to gather dust. And the remaining percentage that do get put to good use get replaced or updated almost immediately.

Our goal here is to walk you through picking out individual parts that will help you avoid not only having to update your system right away but to generate 3 times the power right from the start avoiding the realization that you bought what amounts to a "trickle charger".

Most of the more common kits, the Harbor Freight 45 Watt Kit and the Sunforce 60 Watt Kit are what is known as "amourphous panels". While amorphous panels are less expensive to produce one of the biggest draw backs to using them is that they require much more real estate per watt. A standard 50 watt crystalline panel requires only as much space as is needed for 1 of the 3 or 4 panels from these kits. And while crystalline panels use to be out of the dollar range of most DIY energy makers that has changed dramatically.

Let's start with the solar panel

The panel we would suggest for our "starter system" is not exactly a crystalline panel but a Polycrystalline panel. The Epcom 50 watt panel is approxomately 32" X 22", has a tough metal frame and sells for only $99.00. The 125 watt version of this same panel sells for $199.00 and a little quick math tells you that spending a little bit more money when making your first purchase is going to pay off quickly. The 50 watt panel puts out 2.78 amps and the 125 version puts out a respectable 7.3 amps. So ask yourself "how many panels am I REALLY going to add to this little system of mine". Knowing this and being honest with yourself about what that answer is will help you make a sound decision on your charge controller.

The Charge Controller

The charge controller of these common kits come in either 4 amps for the Harbor Freight Kit 45 watt kit or 7 amps for the Sunforce 60 watt kit. You can make the jump to 10 amps for the reasonable price of $35.00 with the Sunforce 60031 Charge Controller. But you need to be honest with yourself, will you save money in the long run by stepping up and making your first purchase the Sunforce 60032 with 30 amp capabilities and LED digital voltage and battery condition read out.

Next is the Power Inverter

Last but not least is the power inverter that will convert your DC volt power to usable 110 volt to be used with common household appliances etc. The inverter is the most misunderstood and replaced item in any system. Beginners will most often buy the least expensive inverter to get started only to find out that it won't power what they intended to use it for. Be honest with yourself, do the math. How much power does it take to run that computer or shop light hat you want to run on your new solar system. Better then doing the math, purchase a "Kill A Watt Meter". It's a simple device that you plug into the wall and plug your appliance into to read the power useage of your item on it's LED screen.

The least expensive inverters are what is called "modified Sine Wave" and are almost non usable for electric motors, TV's, microwaves or computers. I have always had some inexpensive high wattage modified sine wave inverters in our arsenal, they have their place. But most likely you will want to use your new system for a computer or TV so it's best to step up and get a reliable, quality "Pure Sine Wave" inverter right from the start. In the 300 watt and under category we suggest the Samlex PST 30S that sells for around $128.00.

In the 1000 watt category you can get into the Xantrex ProWatt SW1000 for approximately $279.00 and you won't regret it. This Xantrex has features usually associated with much more expensive units. Remote capabilities, dual GFCI outlets, USB charging ports and more.

Let's put it all together.....

One of the few remaining items you will need is an assortment of wiring. Stranded copper wiring is a valuable commodity to the home energy producer. Start scrounging around and buying up all you can when you can get deals. Stranded only since solid wire has almost no place in the DC world in our opinion. And focus on 10 gauge and thicker. The most expensive wire you'll need will be for connecting your batteries to the inverter. You want to design your system to keep the inverter as close as possible to the batteries. Welding leads from dis guarded, out dated Lincoln welders have always been prime targets for this application. Or committing a set of heavy jumper cables to the cause can work as well. Don't make a move on your wiring though without referring to this chart. The number 1 mistake made by the first timer is under sized wiring.

So let's get it put together. If you need any help at all visit our forum that is 800+ members strong and they will answer any questions you have and have posted pictures and diagrams of their own systems there as well. Ask any question you want, our members love helping someone get started.

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

Tuesday, February 7, 2012

Making a Cheap 12 Volt Timer

From guest Blogger Denise McCracken........

I have two 50 watt solar panels up, in the DC part of my system. I was thinking about putting in a timer to control the outdoor lights, but I did something much simpler. I built a box with a diode and a relay. The diode is between the solar panel power feed and the battery.

Power on the solar side will close the relay. The battery is connected to the lights through a 10 amp circuit breaker, and through the NC contacts of the relay. So, whenever the sun goes down, the lights come on. When it comes back up, relay closes, lights go out, and the batteries charge.

So far, I've gotten by without a charge controller, just the panels and this little switch box that I made.

The schematic is almost trivial, but here it is...

The circuit breaker for the lighting goes into the "to lights" wire, to protect the box and its wiring. You can find one here:

I like aircraft breakers because you can pull them to disable a circuit, if necessary. Here is the one I used.

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

Sunday, November 28, 2010

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!

Sunday, February 7, 2010

Off Grid Renewable Energy Solar Wind Setup Part 1

From shonerboner....

We have 2 Evergreen Solar panels 180 watts each, Tristar 60Amp Controller, 2, 400 watt Air-x wind generators, about 8 marine deep cycle batteries from walmart now. A 250A DC breakerbox from Midnight Solar, Xantrex DR-2412 2400Watt Inverter, and a Reliance transfer switch. So far the system has cost about $6,000 with everything overbuilt to be upgradeable with more solar panels as soon as we get some more funding!