Free Sun Power shining on Solar panels generates free energy by converting sunlight to electricity with no moving parts, zero emissions, and no maintenance Free tutorials, interactive online Design Tools and a Solar Power Simulator at

Run your own Solar Energy System! 5 Meters display charging, power, voltage, & more. Watch the power change as you turn appliances on/off.

Details of the Solar Energy System used in this small, energy efficient, earth sheltered home.

Home Page
System Simulation
About Solar Power
Easy 5 Step Guide
Example Systems
Solar Energy Home
Solar Projects
  Solar Combiner Box
  Mini Junction Box
Terms & Definitions
Basic Tutorials :
  Solar Panels
  Charge Controllers
  Power Inverters
  Storage Batteries
  AC Generators
  Wires & Cables
  Meters & Monitors
Advanced Info :
  Watts & Power
  Solar Radiation
  Battery Wiring Diagrams
Design Tools :
  System Sizing Estimator
  Battery Bank Designer
  Wire Size Calculator
Nasa Animations
Solar Domain Names
Helpful Links
Site Map

Basic Tutorials: Power Inverters
The Power Inverter
Trace (Xantrex) 2.5 KW 12 volts DC to 120 volts AC inverter Unless you plan on using battery power for everything, you will need a Power Inverter. Since the majority of modern conveniences all run on 120 volts AC, the Power Inverter will be the heart of your Solar Energy System. It not only converts the low voltage DC to the 120 volts AC that runs most appliances, but also can charge the batteries if connected to the utility grid or a AC Generator as in the case of a totally independent stand-alone solar power system.
Square Wave power inverters :
This is the least expensive and least desirable type. The square wave it produces is inefficient and is hard on many types of equipment. These inverters are usually fairly inexpensive, 500 watts or less, and use an automotive cigarette lighter plug-in. Don't even consider one of these types of power inverters for a home system.
Modified Sine Wave power inverters :
This is probably the most popular and economical type of power inverter. It produces an AC waveform somewhere between a square wave and a pure sine wave. Modified Sine Wave inverters, sometimes called Quasi-Sine Wave inverters are not real expensive and work well in all but the most demanding applications and even most computers work well with a Modified Sine Wave inverter. However, there are exceptions. Some appliances that use motor speed controls or that use timers may not work quite right with a Modified Sine Wave inverter. And since more and more consumer products are using speed controls & timers, I would only recommend this type of inverter for smaller installations such as a camping cabin.
True Sine Wave power inverters :
A True Sine Wave power inverter produces the closest to a pure sine wave of all power inverters and in many cases produces cleaner power than the utility company itself. It will run practically any type of AC equipment and is also the most expensive. Many True Sine Wave power inverters are computer controlled and will automatically turn on and off as AC loads ask for service. I believe they are well worth the extra cost. I use a True Sine Wave power inverter myself and find that its automatic capabilities makes it seem more like Utility Company power. The Xantrex 2500 watt power inverter I use has a search feature and checks every couple of seconds for anything that wants AC, then it powers up automatically. You just flick on a light switch (or whatever) and it works. When you turn off the light or the refrigerator kicks off for example, the power inverter shuts down to save battery power.
While the Modified Sine Wave inverter (sometimes called a Quasi Sine Wave inverter) is nearly half the price of a True Sine Wave inverter, I would still recommend using a True Sine Wave inverter if you want to supply automatic power to a normal home using a wide variety of electrical devices. Also, most appliances run more efficiently and use less power with a True Sine Wave inverter as opposed to a Modified Sine Wave power inverter.
Grid Tie Power Inverters
If you are connected to normal Utility company power and just want to add some Free Sun Power electricity to reduce your electric bill and you do not need a totally independent system, it is possible that a Grid Tie power inverter will suit your needs. With a Grid Tie power inverter, whatever electricity that your solar panels produce will reduce the amount supplied by the utility company, in effect lowering your bill. And, if you are producing more power than you are using, you can actually sell the extra power back to the utility company! For this type of setup a much smaller battery bank can be installed just to cover short term outages from a few minutes to an hour or two. In fact, if you don't have frequent long term power outages and don't need back-up power, then you will not need any batteries at all. (But, really, what utility company never fails? :)
Input voltages. Should I use a 12, 24, or 48 volt inverter?
The main consideration when deciding on the input voltage (from your battery bank) of your Inverter is the distance between your solar panel array and your battery bank. The higher the voltage, the lower the current and the smaller the (expensive) cables need to be. Of course, when you decide on a system voltage, the Solar Panels, Inverter, and Battery Bank all need to use the same voltage. More detailed information on voltage & current is explained in the tutorial on Power & Watts.
To help decide on which voltage to use, check out our Wire Size Calculator which can tell you what size wire is needed to connect the solar panels to your equipment area. You can try all 3 different voltages to see the change that it can make in wire size.
Inverter Stacking: Using multiple inverters.
Two inverters can be installed in a configuration known as stacking that can provide more power or higher voltage. If two compatible inverters are stacked in series you can double the output voltage. This would be the technique to use to provide 120/240 volts AC. On the other hand, if you configure them in parallel, you can double your power. Two 4000 watt inverters in parallel would give you 8000 watts (8KW) of electricity
Power Inverter considerations
The Power Inverter is connected directly to the batteries and the main AC breaker panel to supply power from the batteries to the loads (appliances). Check out Wires & Cables for more info on the necessary wire size for installing one or use our new Wire Size Calculator. The Power Inverter converts the low voltage DC to 120 volts AC. Power Inverters are available for use on 12, 24, or 48 volt battery bank configurations. Most Power Inverters can also charge the batteries if connected to the AC line. Alternatively, the AC line input could be your own AC Generator in the case of a stand-alone solar power system. When using a AC Generator to charge the batteries, the Power Inverter transfers the AC Generator power to the loads via a relay. This way the AC Generator not only charges the batteries but also supplies your AC power while it is running. If your Generator is at least 5000 watts, you can charge your batteries and have extra AC power at the same time.
How can I determine how many solar panels and batteries I'll need?
This will depend on how much electricity you are going to need and how many days you plan to be able to run on just battery power alone (no sun at all). To assist you in determining the size system you will need, our System Sizing Estimator will help you calculate the number of solar panels you'll need and what size battery bank is required. We also provide a Battery Bank Designer tool to show you how to wire your battery bank for a 12, 24, or 48 volt system.
What kind of wires or cables will I need to hook all this stuff together?
The Wires & Cables tutorial covers this question and provides a handy chart to calculate the required wire sizes based on the voltage of your system and the distances between components. Also, our new Wire Size Calculator tool will calculate wires sizes for you.

For a small system on a budget, a 2000 to 3000 watt Modified Sine Wave power inverter will do the job for around $1200 to $1500. Expect to pay up to $1000 more for a True Sine Wave power inverter if you want to be able to run anything and have the automatic features. These higher quality Power Inverters are computer controlled and once set-up, can control your 120 volts AC, battery charging, and even auto-start compatible AC Generators; all automatically.
If your goal is to provide real home power, A True Sine Wave inverter is really your best choice. The extra cost, in the long run, is a good investment in performance and reliability. For a small seasonal use cabin, a Modified Sine Wave inverter would probably do the job.

Previous Page Top of Page Next Tutorial