Micro-Inverters and the Apocalypse

For those fans of “The Walking Dead”, you may have noticed a micro inverter in last night’s episode.  Therefore, we felt that it is a good time to talk about what a micro-inverter is.

In order to use the power from your solar panels for appliances and household electronics, you have to utilize an inverter.  An inverter inverts the DC power from the solar panels into AC power.  Currently, in the residential market, there are two types of inverters.  There is the string inverter and there is the micro-inverter.  While they both serve the same function in the end, they both do it in different ways.  With a string inverter, the groups of solar panels are wired together in series to form a string.  With a micro-inverter, each solar panel is connected to one micro-inverter.

Why the two options?  Both inverters have their merits and there downfalls.  A string inverter is the most cost effective way to go solar and if the string inverter fails, it is easy to replace.  The downside to a string inverter is that any shading on one solar panel in the string can seriously hurt the power production of that string.  A micro-inverter doesn’t have the shading issues of a string inverter.  If one solar panel is shaded, only that panel and inverter are reduced in power production.  The remaining solar panels will still perform.  With this same idea, if one micro-inverter fails, it doesn’t affect the rest of the solar panels and their production.  The downside to micro-inverters is both their cost and replacement.  Since micro-inverters are installed under the solar panels, it can be difficult to replace them.

In the next article, we will discuss how shading impacts a solar array in more detail.  At least now, you know what a micro-inverter was doing in the apocalypse.

DIY Solar Panels - Fact or Fiction

In recent years there has been a surge in websites and manuals for Do-It-Yourself Solar Panels. There have been some impressive claims as well. "Say adios to your utility", "Go 100% Solar", and "Reduce Your Electricity Bill for Pennies" is probably my favorite.  As an experienced Solar professional, I can tell you all of these to-good-to-be-true claims are more fiction than fact.

In this article I will discuss what a DIY Solar module is and will help you determine when it is and isn't appropriate to use.

What is a DIY module? 

A DIY Solar module is created when solar cells are soldered together in series and parallel. The common module size you see on the market is a 36-cell configuration.  At the end of the series and paralleled cells will be two leads used to connect the module to either additional modules or a load.  At this point you will need to add glass, an encapsulant, and a frame.  This entire setup becomes your solar module. 

From this point, a basic knowledge of electricity will be required.  Some specific skills and terms you should be familiar with are: 


Ohm’s Law (Volts = Amps X Resistance)

Series vs parallel wiring

Bypass diodes

Basic carpentry or fabrication

Please keep in mind that this is strictly to create the Do-It-Yourself Solar module and not what you are going to do with it once completed.

You can use DIY solar modules only in limited situations.  When there is a building department, insurance company, or utility company involved your DIY Solar Panel will NOT be able to be used.  Solar Panels must be tested to UL1703 standards. Once you've constructed a solar module from an assembly of parts, this new assembly is not UL listed.  Since the above depicts the majority of DIY situations, for safety and legal reasons, we strongly suggest that you do not attach your DIY Solar Panels directly to your house. 

So what can you do with DIY Solar modules?  You can use them for portable power that do not involve the situations listed above (building department, utility and insurance company).  For example, you could connect your DIY solar module with a charge controller and battery bank.  Now you have what is considered a basic DC off-grid system.  This is great for remote water pumping.

Do not fall victim to the idea that DIY solar modules will slash your electrical rates.  When In fact, DIY solar modules are illegal to tie into your existing electrical system if you are connected to a Utility.