A solar electrical generating system consists of solar panels, charge controllers, batteries or some form to store electrical energy, and inverters that convert low DC voltage to AC voltages that can be used by you the consumer. We will discuss each one of these below.
There are a number of types of solar panels, but the two main types are monocrystalline and polycrystalline. There are also thin film technologies and multilevel panels that are being developed.
I have a flexible multi teared panel and due to the multiple waves lengths of light it excepts it generates almost the same power on a cloudy day as a sunny day. Very impressive but also very expensive per watt in cost.
These days the monocrystalline and the polycrystalline panels are about the same. There was a time when monocrystalline was a better product but also more expensive, but polycrystalline panels have come a long way and will give you the same service but at a better price.
The life time in years is what should be taken into account. This has less to do with the material the solar cell is made of but rather the quality and material of the encasing of the solar cells. About 25 years is what most vendors are touting.
I have a 50 watt monocrystalline panel going on 25 years and it still produces 50 watts as rated but that puppy cost me 400 American dollars.
Solar Panel Charge Controllers 'Whats that?'
Consumer solar panels typically come in two voltage ratings, 12 & 24 volts. These are designed to work with 12 or 24 volt battery systems and inverters. But the voltage that comes off the panels are around 20 volts for a 12 volt system and 40 volts for a 24 volt system. Your batteries are not going to last too long being hit with these voltages for any period of time. So you need something that will take what comes off the solar panel and feed the correct voltage and current that the battery need at its current state of charge.
This is what a solar charge controller does, it feed the correct voltage and current to the batteries to maintain the best state of charge. Most charge controllers have computer software that figures out what the battery need to maintain optimum health and charge.
There are three types of charge controllers, MPPT, PWM, and controllers for connecting to the grid.
MPPT controllers track the voltage from the panel and play with it to give you the maximum power for your situation. But are very expensive. MPPT stands for maximum power point tracking.
PWM controllers are less expensive but they won't play with the voltage and current to give you the maximum power for your situation. Compared to an MPPT controller you could be losing hundreds of watts of power. I use them for my cloudy day panels which works out fine. PWM stands for pulse width modulation. It hits your battery with pulses to control the amount of current your battery receives.
Batteries are the most important link in the chain of any home powered, off grid, system. Batteries are where your hard earned power is stored to be used when needed most. Batteries are also the most expensive part of any off grid solar system.
There are many types of batteries but for solar, as of this writing, flooded and sealed lead acid batteries are the most common. They are slow to charge and how they are charged and used will determine their life. Dealing with lead acid batteries is complex – If you want max life out of them. Which can be tens of years – but they are still the best bang for your buck.
Once you have harvested your power and stored that power in your batteries you now need to convert that power to, what called, usable energy. That is energy that's going to run your electrical gadgets.
Now every time you change power from one form to another or one place to another there are losses. When the power from your panels goes through the charge controller to the batteries there are losses at every step. There are losses even when you go from your panels to the wires the bring the power to the charge controller. So having the least amount of steps your harvested power has to go through translates into more power in your pocket.
So setting up your situation to use the 12 or 24 volts right out of the battery is best, but that can get expensive changing out everything you want to use to run on 12 or 24 volts. The solution is to install inverters.
Inverters change 12 or 24 DC volts into ~115 AC volts that can be used by most everything that can run off of the grid. But there is a cost, it takes power to run the inverter and that cost goes up the more power you suck out of your inverter. That is the cost of the unit your running plus increased losses from the inverter the more power the inverter converts. So running as much as you can off of 12 or 24 volts DC will save you more stored power. I say stored power because in the day time you should have enough panels to go hog wild, power wise. Panels are cheap these days (90 cents a watt can be found) and last for many years. Batteries are still very expensive and if not treated right can last for just a few months at best, but if treated right can also last for many years.
Why Go Solar?
Well thousands of small business in California wish they had. Thousands of small business went out of businesses when the cost of electrical power went through the roof a few years ago.
I was personally effected when my meat place, that offered meat at a great price well below the super market price, was forced out of business when their freezer electrical costs went from a few hundred dollars a month to a few thousand a month.
Energy is the life blood to life as we know it, get into a position of power and secure your energy source.
How to Build an Off Grid Solar Power Plant
Links to Mathematics and Calculators
More Links to Alternative Energy Information
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