The basics of solar systems

For those of you who are interested but need a primer on the different types of solar systems that are used to generate power for your house, here is the basic information:

There are three commonly used types of solar power systems

1 – Grid Tie Solar

2 – Off Grid Solar Systems

3 – Grid Tie Systems with Battery backup

Each of these three types of systems work well for power generation but, are generally applied under different circumstances.


Grid Tie solar systems are the most common.

With this type of system, you use your solar panels to generate power when the sun is up. This power goes through an inverter and is converted from DC power (like your car or boat runs on) to AC power (the power you use in your house). Since AC power cannot be stored, you either use it or lose it. When the sun is down or it is too cloudy to activate your panels, you draw power through the grid from CFE.


With the solar system installed using a grid tie method, your power production is used first by you, and any excess you produce during the day is fed back into the grid, for use by other people. In order to do this, CFE supplies you with a bi-directional meter (the thingy at the end of your property where the power lines come into your house that the CFE guys come by every two months to read.) Currently, yours is only one direction. It reads the power being fed into your house and CFE charges you for this power based on how much you use. The bi-directional meter is important because it reads both the power you use from CFE and the power you are putting back into the grid. The power you put into the grid is a credit for you with CFE.

With a grid tie solar system, CFE comes around as normal and reads your meter but now, they read two sets of numbers. The first is the power you have used during the previous two months. The second, is the amount of power you have sent back into the grid. The difference between these two numbers is either the kilowatts you will have to pay CFE for, or the kilowatt credit you have with CFE. Please note: CFE has a minimum charge, even if you have a kilowatt credit. Currently, $43.00 pesos per billing cycle or, $21.50 pesos per month.

This is by far the most common system in use today worldwide. It is the least expensive to both install and maintain, and is the least hazardous. It also ensures that every kilowatt of power you produce is being used, thereby maximizing your contribution to lessening the damage to our environment.

The major drawback to this system is that, when the grid loses power, you do as well. This is a worldwide safety standard that prevents your system from feeding power to the grid during a power outage, so as not to injure or kill workers during their work to restore power.

Off Grid Solar Systems are less common.

These systems are used mostly where there is no power grid (hence the name), such as the Australian outback or (closer to home), rural areas up around the biosphere that have no power grid.

Off grid systems use batteries to store the power produced by the solar system, which is then run through an inverter to convert the power from DC to AC. These systems are much more complicated to install and require a lot more maintenance. Also, the battery life is not great, 3 – 5 years based on use and climate conditions.

The basic function works like this: Your solar panels produce DC power. This power is then sent to the batteries for storage and later use and/or directly to your house through an inverter for conversion to AC power. Once the sun goes down, or it is too cloudy for the solar panels to produce enough power to meet your needs, the batteries send their power through the inverter where it is converted to AC power and is then used by your house.


The advantage to this system is you are free from dependence on CFE to supply you with power.


     The disadvantages are many and include:

     A hugely higher initial cost for the system and set up

     Higher maintenance costs

     High battery turnover and a high cost for battery replacement

     A more dangerous system

Grid Tie with a battery backup least common and most expensive:

Many people have been looking at this as the best solution. However, it has major drawbacks as well.

This system is a combination of the two previous systems. You are connected to the grid and deal with power usage and power credit the same way as a normal grid tie system and you have a battery system that comes into operation when there is a power outage to the grid. Sounds like a perfect solution, right?

Unfortunately, you will have a far more complicated system requiring more ongoing maintenance and then there is that problem of battery replacement because, even when not using batteries they wear out. This system can double the cost of a normal grid tie system and when weighing the benefits, it is (in my opinion) cost prohibitive.

While those of us who live on the Emerald Coast and even Merida do still suffer from power outages, they are not lengthy and not nearly as often. My suggestion to anyone considering this type of system, is to install a generator instead. For a fraction of the cost, you can install a generator system that can power your whole house and will come on automatically in the event of power failure. Or, you could go with a portable generator wired directly to your breaker panel that will take care of your critical items and even run an AC unit or two.

Let’s face it, the reason we consider solar systems is mainly so we can save money. For most people, the benefits for the environment  are a nice bonus. So, why even consider a system that can cost you as much or more than what you are already spending on power through CFE?

Do yourself a favor and get a solar system installed for your home or business. It is the best investment you can make. Just make sure you get the system that is right for you.

   Emerald Coast Solar

Putting the power of the sun to work for you