A (very) Basic Overview of Solar Power

Basic Solar Power System

http://www.alternative-energy-news.info/images/technical/solar-power.jpg

I have been fascinated by Solar Energy ever since I was a kid.  There was something very "space age" about it, and in fact it really was the space industry that pushed the technology to the extent that made it available to the public.  While I don't buy into much of the pseudo-scientific, "eco-friendly", modern environmentalism (I am more of an evidence-based environmentalist), it is pretty obvious that modern coal-based electricity, while more efficient, produces a lot of pollution.  Solar is much more clean since its production produces minimal waste, and a good solar panel will last and function well for 25-30 years!  It also provides another layer of self-sufficiency.

Today, I just want to give a very basic overview of a solar power set-up.  I am not going to get into the science/physics of solar power.  I will probably get more into the details in later posts, but today I'll stick to the simple basics.

There are four main components of a solar power system:

1. Solar Panels
2. Charge Controller
3. Batteries
4. Power Inverter

The basics of a photovoltaic cell.

 http://static.howstuffworks.com/gif/solar-light-cell.gif

An individual solar cell.

http://upload.wikimedia.org/wikipedia/commons/9/90/Solar_cell.png

Solar Panels
Solar panels are composed of individual solar cells.  A solar cell (aka photovoltaic or photoelectric cells) has the ability to convert light energy into electrical energy.  Certain materials are better at converting light to electricty than other materials.  Traditionally, and currently, silicon crystals are by far the most common.  This is considered a "bulk" material since the set-up is fairly thick (think of the traditional solar panels you've seen on a roof or road sign).  Scientists are continuing to develop Thin Film technologies that use much less material to still produce a current.  There are plans of "painting" buildings with solar organic dyes or coating windows with a solar polymer (that also acts like a tinting), but so far, Thin Film has not been as successful yet.  Most solar cells are about 10-25% efficient at producing electricity from sunlight.

A number of individual solar cells are connected to form a solar module (commonly called a "solar panel"), and multiple solar modules are wired together to create a solar array.

Charge Controllers
Charge Controllers are used to properly manage the voltage flowing to the batteries.  Voltage too high can damage the batteries.  The minimum charge controller for a home uses a technology called Pulse Width Modulation (PWM), but the best charge controllers use Maximum Power Point Tracking (MPPT) technology.  This technology is rapidly changing.

Batteries
Deep Cycle Batteries are needed to store energy that will be used frequently.  These batteries can be drained and recharged many times without damage.  Marine Batteries, Golf Cart Batteries, and RV batteries can be used for smaller applications, but more specialized batteries will be needed for larger applications like powering your home. 

Power Inverters
Solar power is Direct Current (aka DC).  DC is battery power.  If you are using only battery powered devices, such as a simple solar powered battery charger for things like flashlights or cell phones, then a power inverter is not required.  However, if you want to power anything that "plugs in" to the wall, then you will need to convert that DC to Alternating Current (AC).  Almost all power inverters will convert to 120 volts AC.  Again there is a variety of technologies available.  Square Wave inverters should be avoided as they are very hard on the devices they power.  Modified Sine Wave Inverters are far better, and they are really the least expensive and usable power inverters.  The best power inverters are the True Sine Wave Inverters, but they come with a higher price tag.  Finally, if you plan on using solar power for your needs, but would also like to sell back power to the electric company, then you will need a Grid Tie Power Inverter.  I'll get into how this works in future posts.

Another diagram of a basic solar power system.

http://www.small-cabin.com/pic/solar-power-setup-diagram.jpg

So that is it.  The four basic components of a Solar Power System.  Solar Power is a great addition to your Permaculture System, and it is getting more economical every year.  I plan on writing some more posts on various aspects of solar power in the next few weeks.