NEW! SOLAR POWER CALCULATORBuild Your Own Solar Power System Instructions
November 28th, 2008
This article will teach you the basics of solar power for producing your own electricity.
It is easy to confuse solar power for the production of electricity, with solar to produce heat. They are different topics. Solar power uses photovoltaic cells to produce electricity called solar panels or PV panels. These panels release electricity when sunlight strikes them. In contrast, a solar heater uses the sun to actually heat water or air flowing through it and it has nothing to do with electricity and PV panels.
Solar panels are pointed at solar south in the northern hemisphere and solar north in the southern hemisphere. Solar north and solar south are a little different than magnetic compass north and south.
The sun strikes the PV panels which creates an eletrical charge which is directed to the output terminals which product DC (direct current) somewhere between 6 and 24 volts depending on the solar panels. Most solar panels are set to output 12 volts.
The total amount of solar power produced by your system is based on what is called Peak Sun Hours. Peak Sun Hours represent the average amount of sun available per day throughout the year for your specific locality.
It is estimated that at "peak sun", 1000 W/m² of power reaches the surface of the earth. One hour of full sun provides 1000 Wh per m² = 1 kWh/m² - representing the solar energy received in one hour on a cloudless summer day on a one-square meter surface directed towards the sun.
The daily average of Peak Sun Hours is used for calculation purposes in the design of the system. To see the average Peak Sun Hours for your area in the United States, go to the solar power calculator at http://www.mysolarsecret.com/solar-power-calculator.html and select the city nearest you under the wording "Select the city nearest you for the number of hours per day of sun" about half way down the page. Follow your eyes across the webpage to the box on the right side of the screen to see the Peak Sun Hours for your area.
Components You Will Need In Your Solar Power System
The four primary components for producing electricity using solar power, which provides common 120 volt AC power for daily use are: Solar panels, charge controller, battery and inverter. Solar panels charge the battery, and the charge regulator insures proper charging of the battery. The battery provides DC voltage to the inverter, and the inverter converts the DC voltage to normal AC voltage.
Solar Panels
The output of a solar panel is usually stated in watts, and the wattage is determined by multiplying the rated voltage by the rated amperage. The formula for wattage is VOLTS times AMPS equals WATTS. So for example, a 12 volt 60 watt solar panel measuring about 20 X 44 inches has a rated voltage of 17.1 and a rated 3.5 amperage.
V x A = W
17.1 volts times 3.5 amps equals 60 watts
If an average of 6 hours of peak sun per day is available in an area, then the above solar panel can produce an average 360 watt hours of power per day; 60w times 6 hrs. = 360 watt-hours. Since the intensity of sunlight contacting the solar panel varies throughout the day, we use the term "peak sun hours" as a method to smooth out the variations into a daily average. Early morning and late-in-the-day sunlight produces less power than the mid-day sun. Naturally, cloudy days will produce less power than bright sunny days as well. When planning a system your geographical area is rated in average peak sun hours per day based on yearly sun data. Average peak sun hours for various geographical areas is listed on the solar power calculator webpage at http://www.mysolarsecret.com/solar-power-calculator.html
Solar Panels For Sale
Solar Panel 18-Watt 12-Volt Deep-Cycle Battery Charger
13 Watt General Purpose Solar Module
Bird-X - SOLPAN2-CRTTR - CritterBlaster Pro Solar Power Panel Accessory - Black - 37 L x 15 W in.
ROOF/GABLE SOLAR PANEL (Ventamatic VXSOLARPANEL)
Sunsei SE-16000 Solar 260-Watt 16.5-Volt Charger
Sunsei SE-24000 Solar 400-Watt 16.5-Volt Charger
Sunsei SE-4000 Solar 65-Watt 16.5-Volt Charger
Sunforce 15-watt Solar Charger with 7-amp Charge Controller
60 Watt Solar Panel with 7 Amp Charge Controller, Model# 37015
10 Watt Black Frame Mono-crystalline Solar Panel and Battery Charger
20 Watt Black Frame Mono-crystalline Solar Panel and Battery Charger
40 Watt Black Frame Mono-crystalline Solar Panel and Battery Charger
Learn About Wiring Solar Panels And Batteries
There are three types of wiring configurations that are relatively easy to learn. Once mastered, the job of wiring batteries or solar modules becomes easy as pie. The three configurations are:
Series wiring
Parallel wiring
And a combination of the two known simply as series/parallel wiring.
Solar panels can be wired in series or in parallel to increase voltage or amperage respectively, and they can be wired both in series and in parallel to increase both volts and amps. Series wiring refers to connecting the positive terminal of one panel to the negative terminal of another. The resulting outer positive and negative terminals will produce voltage the sum of the two panels, but the amperage stays the same as one panel. So three 12 volt/3.5 amp panels wired in series produces 36 volts at 3.5 amps. Four of these wired in series would produce 48 volts at 3.5 amps.
Wiring Solar Panels In Series
To wire any device in series you must connect the positive terminal of one device to the negative terminal of the next device.
Wiring Solar Panels In Parallel
Parallel wiring refers to connecting positive terminals to positive terminals and negative to negative. The result is that voltage stays the same, but amperage becomes the sum of the number of panels. So three 12 volt/3.5 amp panels wired in parallel would produce 12 volts at 10.5 amps. Four panels would produce 12 volts at 14 amps.
Wiring Solar Panels In Series and Parallel
Series/parallel wiring refers to doing both of the above - increasing volts and amps to achieve the desired voltage as in 24 or 48 volt systems.
You might be asking why in the world would someone want to put them self through wiring both in series and in parallel? Let's say that you want to increase the Amp hour rating of a battery pack so that you could run your appliances longer but you needed to wire the pack in such a way as to keep the battery pack at 12 volts, or you want to increase the charging capacity of your solar array but you needed to wire the solar modules in such a way as to keep the solar array at 34 volts, well, series/parallel wiring is the only way to do that.
Charge Controller
A charge controller monitors the battery's state-of-charge to insure that when the battery needs charge-current it gets it, and also protects the battery from being over-charged. Connecting a solar panel to a battery without a regulator seriously risks damaging the battery and can cause a hazard.
Charge controllers (or often called charge regulator) are rated based on the amount of amperage they can process from a solar array. If a controller is rated at 20 amps it means that you can connect up to 20 amps of solar panel output current to this one controller. The most advanced charge controllers utilize a charging principal referred to as Pulse-Width-Modulation (PWM) - which insures the most efficient battery charging and extends the life of the battery. Even more advanced controllers also include Maximum Power Point Tracking (MPPT) which maximizes the amount of current going into the battery from the solar array by lowering the panel's output voltage, which increases the charging amps to the battery - because if a panel can produce 60 watts with 17.2 volts and 3.5 amps, then if the voltage is lowered to say 14 volts then the amperage increases to 4.28 (14v X 4.28 amps = 60 watts) resulting in a 19% increase in charging amps for this example.
Many charge controllers also offer Low Voltage Disconnect (LVD) and Battery Temperature Compensation (BTC) as an optional feature. The LVD feature permits connecting loads to the LVD terminals which are then voltage sensitive. If the battery voltage drops too far the loads are disconnected - preventing potential damage to both the battery and the loads. BTC adjusts the charge rate based on the temperature of the battery since batteries are sensitive to temperature variations above and below about 75 F degrees.
Charge Controllers For Sale
Solar Charge Controller for solar/wind generator/Wind Turbine - 45 amps
Solar Charge Controller for solar/wind generators - 60 amps
Solar Controller 12-Volt Battery Charge Monitor
10 Amp Solar Charge Controller
15-watt Solar Charger with 7-amp Charge Controller
4.5 amp 12 volt Solar Charge Controller Regulator by Morningstar
4 Amp solar charge controller - CDT-C4 regulator 12V #35004
20 Amp Solar Charge Controller with Digital Display
Sunsei SE-CC25000 25 Amp Solar Charge Controller
60 Watt Solar Panel with 7 Amp Charge Controller, Model# 37015
Sunforce Digital Charge Controller - 10 Amp, Model# 600311
Xantrex Charge Controller for DC Charging Sources - 40 Amp, Model# C40
Xantrex Charge Controller for DC Charging Sources - 35 Amp, Model# C35
Xantrex Charge Controller for DC Charging Sources - 60 Amp, Model# C60
I hope you are well on your way to designing your own homemade solar power system from reading this article. If you need additional help in the form of an easy, step-by-step guide on exactly what parts you need to buy and how to connect the parts together see the top two solar panel how to guides that I reviewed at http://www.mysolarsecret.com
Battery
The Deep Cycle batteries used are designed to be discharged and then re-charged hundreds or thousands of times. These batteries are rated in Amp Hours (ah) - usually at 20 hours and 100 hours. Amp hours refers to the amount of current - in amps - which can be supplied by the battery over the period of hours. For example, a 350ah battery could supply 17.5 continuous amps over 20 hours or 35 continuous amps for 10 hours. To quickly express the total watts potentially available in a 6 volt 360ah battery; 360ah times the nominal 6 volts equals 2160 watts or 2.16kWh (kilowatt-hours). Like solar panels, batteries are wired in series and/or parallel to increase voltage to the desired level and increase amp hours.
The battery should have sufficient amp hour capacity to supply needed power during the longest expected period "no sun" or extremely cloudy conditions. A lead-acid battery should be sized at least 20% larger than this amount. If there is a source of back-up power, such as a standby generator along with a battery charger, the battery bank does not have to be sized for worst case weather conditions.
The size of the battery bank required will depend on the storage capacity required, the maximum discharge rate, the maximum charge rate, and the minimum temperature at which the batteries will be used. During planning, all of these factors are looked at, and the one requiring the largest capacity will dictate the battery size.
Deep Cycle Batteries For Sale
Basement Watchdog Deep Cycle Battery (30HDC140S)
Glen Tronics B-1000 Standby Deep Cycle Battery
Glen Tronics B-2200 Standby Deep Cycle Battery
MK Deep Cycle Gel Cell 12 Volt Battery for Backup Sump Pumps
Powerstar 12V 33AH Group U1 Deep Cycle Sealed Battery
Optima Blue Top D34M High-Power Deep-Cycle Battery (870CA)
Optima Dual Post 750 CCA Deep Cycle Marine Battery
Inverter
An inverter is a device which changes DC power stored in a battery to standard 120/240 VAC electricity (also referred to as 110/220). Most solar power systems generate DC current which is stored in batteries. Nearly all lighting, appliances, motors, etc., are designed to use ac power, so it takes an inverter to make the switch from battery-stored DC to standard power (120 VAC, 60 Hz).
In an inverter, direct current (DC) is switched back and forth to produce alternating current (AC). Then it is transformed, filtered, stepped, etc. to get it to an acceptable output waveform. The more processing, the cleaner and quieter the output, but the lower the efficiency of the conversion. The goal becomes to produce a waveform that is acceptable to all loads without sacrificing too much power into the conversion process.
Inverters come in two basic output designs - sine wave and modified sine wave. Most 120VAC devices can use the modified sine wave, but there are some notable exceptions. Devices such as laser printers which use triacs and/or silicon controlled rectifiers are damaged when provided mod-sine wave power. Motors and power supplies usually run warmer and less efficiently on mod-sine wave power. Some things, like fans, amplifiers, and cheap fluorescent lights, give off an audible buzz on modified sine wave power. However, modified sine wave inverters make the conversion from DC to AC very efficiently. They are relatively inexpensive, and many of the electrical devices we use every day work fine on them.
Sine wave inverters can virtually operate anything. Your utility company provides sine wave power, so a sine wave inverter is equal to or even better than utility supplied power. A sine wave inverter can "clean up" utility or generator supplied power because of its internal processing.
Inverters are made with various internal features and many permit external equipment interface. Common internal features are internal battery chargers which can rapidly charge batteries when an AC source such as a generator or utility power is connected to the inverter's INPUT terminals. Auto-transfer switching is also a common internal feature which enables switching from either one AC source to another and/or from utility power to inverter power for designated loads. Battery temperature compensation, internal relays to control loads, automatic remote generator starting/stopping and many other programmable features are available.
Most inverters produce 120VAC, but can be equipped with a step-up transformer to produce 120/240VAC. Some inverters can be series or parallel "stacked-interfaced" to produce 120/240VAC or to increase the available amperage.
Inverters For Sale
Xantrex Technologies 851-0400 XPower Plus 400-Watt Inverter
Xantrex Technologies 851-0178 XPower 175-Watt Micro Inverter
Cobra CPI 475 400 Watt Power Inverter
Jensen JP30 300 Watt Power Inverter
Duracell DC to AC Pocket Power Source Inverter 175 Watt #813-0291-07
Cobra CPI 1575 3000 Watt 12 Volt DC to 120 Volt AC Power Inverter
Cobra CPI 875 1600 Watt 12 Volt DC to 120 Volt AC Power Inverter
Xantrex Technologies 851-0700 XPower Plus 700-Watt Inverter
Belkin F5C400-300W 2 Outlet Dc/Ac Inverter
Vector VEC024BCA 400-Watt Inverter with Case
XANTREX XPOWER POWERSOURCE MOBILE 100 852-0281
Xantrex Technologies 852-0400 XPower PowerSource 400-Watt Portable Inverter
Xantrex Technologies 851-0401 XPower Plus 400-Watt Inverter
Tripp Lite PV375 PV 375W 12V DC to AC Portable Inverter with DC Auto Power Outlet
Tripp Lite PV150 PV 150W 12V DC to AC Portable Inverter with DC Auto Power Outlet
Duracell 852-0281-07 DC to AC 100 Watt Inverter & 4.0 Amp/Hour Lithium Ion Mobile Power Source
Cobra CPI 2575 5000 Watt 12 Volt DC to 120 Volt AC Power Inverter
Solar #PI4000X - 400 W Power inverter
I hope you are well on your way to designing your own homemade solar power system from reading this article. If you need additional help in the form of an easy, step-by-step guide on exactly what parts you need to buy and how to connect the parts together see the top two solar panel how to guides that I reviewed at http://www.mysolarsecret.com
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