Cheap Electricity for Everyone? Micro Inverters Are Making Solar Affordable for Everyone

Tuesday | Filed in: Solar Install Technology

Solar micro inverters are taking the solar home energy market by storm. A homeowner with some basic handyman skills can now purchase solar starter kits, install himself (mostly), and add additional solar panels as the budget will permit.

Small solar systems are dramatically easy to design and install. Well maybe not dramatically, but doable for the handyman. You should use a licensed electrician to hook up the system, but other than that, if you can fix shingles on your roof, there is a good chance you can now install your own solar system, a few solar panels at a time.

If you’re just getting familiar with solar electric technology, you probably know at this point that there are two major components necessary to produce usable electricity from the sun. Simply slapping solar panels up on your roof and running wire down to your home won’t do a lot of good unless you plan on vaporizing your spouse. To convert that direct current from the solar panels into usable electricity, what is required is a pretty bulky box called an inverter.

Inverters are the device in a solar system that converts DC (direct current) electricity that the solar panels product to AC (alternating current) that your home appliances use. So, you might imagine that a “solar micro-inverter” would simply be a smaller version of this box, right? The short answer is, “uh-huh”. In sum, the micro-technology is coming on strong for many reason. To understand why though, let’s get a little more familiar with “regular” inverters and how they work with solar panels.

In a conventional solar power system, interdependent strings of solar panels are placed on roofs and are wired in series or Christmas tree fashion. (One light goes out, the string goes down.) By the same token, if one solar panel gets obstructed even by just a bit by a big leaf, bird poop, or lovely tree shade, the entire string of solar panels suffers, sending significantly less or even no raw power down the line. Each solar panel needs to work with other panels in the string to get raw power to the inverter.

When using solar micro inverters, the micro inverter is attached to every solar panel in the system and each one is capable of converting direct current from its solar panel into usable electricity, independent of other solar panels on the string. This means that even if one solar panel gets shaded a little bit by dust, bird poop, or a tree, the other panels are still capable of feeding usable electricity into your home or business. (Source, Solar Power Rocks).

Solar starter kits are becoming very popular now. A major advantage to solar micro inverters are modularity and scalability. Let’s say you want to add an electric car in two years, but you don’t want to oversize your system now because you won’t get a check from the utility for excess production (or even a thank you.) Due to the nature of microinverters, you can almost always just slap on another solar panel, micro inverter. Ideally you’d want to get it sized right the first time to avoid having to increase the racking system and number of roof penetrations, but this is still more scalable than a string inverter.

With string inverters you have to adhere to a regimented solar string design, and an upgrade would require a number of things from a different inverter to a large wing of panels to fit the string configurations.

Up to 16 micro-inverters can be linked in parallel per solar AC branch. That does not mean you can only have 16 max solar panels, you can have literally any number of them from one to whatever your electrical service will accommodate. It is just good because you can fit more per branch than most solar string inverters which may cap out at 11 or 12 per string. This isn’t a giant advantage but it’s nice for the solar installers wiring small systems.

No clunky box downstairs. These solar inverters go on the back of each panel, on the roof, so there’s no need for a big string inverter downstairs by your meter. That eliminates concerns about string inverter placement and clearance issues, conduit run eyesores, keeping the inverter out of the sun, etc. Also no need for DC switching points.

Shading of your solar panels is another problem that is reduced. This is the big one. If you shade enough solar panels in a row, you can bring the broken voltage of the entire string low enough so that the inverter just stops, creating zero power output. However, if you have say, 5 solar panels shaded on an 8 solar panel array, those 3 solar panels just keep kicking with micro inverters, each one creating maximum power.

Furthermore, if dust, grime, or bird poop are getting on solar panels disproportionately, they can drag down the power of the whole solar string, much like stepping only a small portion of a water hose. Remember: the solar string inverter maximizes power output for the whole string, not each solar panel, so if some solar panels are suboptimal, so is the whole string.

Single point of failure. This is really up for debate. Some would argue that no single point of solar panel failure is better because if one inverter goes out you still have power production while you’re waiting to get fixed up. Others would argue that you have simply multiplied the possibility of failure dozens of times.

Here is where solar micro inverter get sexy. Residential homeowners with some basic home improvement skills can install most of their own solar systems. Electricians do not need to be there all day wiring, they simply perform the connection at the main panel.

All things being equal, the fact that you can buy small solar systems and add panels as your budget allows. That by itself is enough to consider using small solar systems. Use as many or as few modules as you want or need on different surfaces of your roof. Solar panels can now be installed a panel at a time. Solar installers and homeowners can now create a solar panel system of almost any size.

Credit Source; Solar Power Rocks.

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