SolarUnplugged Direction

It’s been a while since my last post and I have been reflecting a lot on the direction of SolarUnplugged.  I originally set out to start a resource for the homeowner to learn the ins and outs of solar and be more informed.  I have spent too many years in solar as a professional and have seen too many undesirable things happen.  After a recent chat with a colleague of mine and the decline of incentives, it became clear that I need to re-engage in this pursuit and put more time in it as well.

With all the changes going on in the industry with tariffs and tax credits, it would s eem that solar is doomed.  Well, at least that is what most people would want us to think.  Sure, the incentives were great things.  They drove down the cost of solar and made it more affordable for everyone.  But those same incentives did something else- they brought more greed and bad practices as well.  I hate to say that, but it’s true.  The incentives drove a lot of companies to enter the arena who weren’t necessarily the best companies.  And then the market became quickly saturated and quality went out the window.

When the incentives came, people left the realm of energy conservation and went to the highest maximum array they could put on their house.  Please don’t get me wrong, it was a strategy that worked for the moment.  But in the long term, I am not here to teach that methodology.  My goal is to show you how to optimize your house and save as much energy and money as possible first.  Then, I can show you how to design your solar array to match your new needs.  Trust me when I say, there are ways to make all of this more affordable without the incentives.  It just takes a little bit more time.  But the result is you being more sustainable and freer. 

So why am I sharing all of this in a blog post, because I think the change is a good thing in the long run.  It will shake out a lot of unscrupulous companies and already has.  The change will also force the industry to re-employ best practices to be competitive once again.  Sometimes, incentives can cause some real negative side effects as well.

With all that said, my next blog posts are going to start really drilling down into proper system design and practices.  I plan on sharing the processes I use to develop and design the correct system size and types for my clients.  Issue like shading strategies, energy consumption/usage, site analysis and much more will be covered.  There are so many ways in which you can really optimize a system that just isn’t discussed anymore.  I also plan on speckling in some overall sustainability strategies as well. 

Bypass Diodes

Imagine you are driving down the highway.  All the sudden, all traffic comes to a stop.  There is an accident ahead.  Luckily, there is a secondary road you can take and keep moving forward.  Without this secondary pathway, you would be stuck on the highway.  Solar modules function in the same way as above.  If there is even a little bit of shade, the flow of electricity is blocked.  By adding bypass diodes, a solar module now has multiple pathways.  This allows for the electricity to flow even if there is a blockage.

Typical solar modules will have at least three bypass diodes.  These three diodes separate the solar module into three sections.  In other words, your solar module has three pathways for electrical production.  If one section of the module is shaded from the Sun, the other two sections will still produce electricity.  This does mean the module will be reduced to 2/3 of its normal production.  However, without the bypass diodes, the production would be zero.

The question now is how these sections are created.  If you look at your solar module, you will notice silver tabs at the bottom.  And typically, there will be three separate silver tabs.  This tells you how the module is divided into sections (See figure 1).  Because of the bypass diodes, each of these sections can function independently of the other two.

What does this mean for your solar array?  If you have a location for your solar array that has some shading issues, you can still optimize that array.  Let us look at two examples:

Figure 1

Example one:  You have morning shade that affects the Eastern edge of your array.

In this example, it would make sense to mount your modules in portrait.  This is just like when you print a piece of paper.  The longer side of the module faces North-South.  By mounting the solar module this way, we are allowing the bypass diode to do its work.  If the Eastern edge of the array is shaded, we may lose a few sections in our modules, but the remaining sections will still produce electricity. 

Example two:  You have morning shade that will cover the bottom edge of the array.

In this example, if we mounted our array in portrait like above, we would have zero production.  This is because we have blocked every bypass diode.  Mounting the modules in landscape would be a better idea.  By doing this, you will lose roughly 1/3 of your electrical production during the shade.  But the bypass diodes still work, and you get 2/3 production.

Remember, when it comes to off-grid arrays, our goal is maximum production.  This allows us to have a more reliable off-grid array.  And that reliability will also translate into a longer lasting system.

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.