Let’s dive into solar inverters – the rather bland looking electronics that unlock your solar array’s superpower.
If you think about solar panels as the body of your solar energy system, then you can imagine the inverter is its brain. Panels and inverters work together to ensure your system is generating the maximum amount of electricity it can.
We are all familiar with solar panels, as they are the most visible part of a solar energy system. However, the inverter is an equally important component to know about, as it allows energy captured by your panels from the sun to be converted into usable electricity for your home.
ReVision Energy installs inverters from SolarEdge and Enphase, two long-standing companies in the solar industry that have set the standard for innovative, high quality inverter technology. The inverters we use for our projects meet rigorous safety and efficiency standards, and allow us to design, install, and monitor our customers’ systems for continuous, maximum output.
Other than solar panels, the other major component of a solar electric installation is the solar inverter. Solar energy doesn’t create electricity in a form that can power your refrigerator or charge your computer. Inverters transform the power generated by solar panels into a form of electricity you can actually use in your home.
An inverter is a piece of electrical equipment that generates grid-compliant alternating current (AC) electricity from the raw direct current (DC) electricity produced by your solar panels. It is responsible for allowing the electricity from the solar modules to flow and ensures that power is clean (from an electrical perspective) and able to interact with the grid. A solar project can have on or several inverters, depending on the design, as well as power optimizers that work with inverters (more on that below).
The graphic above illustrates how the flow of electricity generated by your panels moves through the inverter technology and into your home.
A solar project can have multiple inverters, depending on the size of the system. They are very important pieces of equipment in a rooftop or ground mount solar system, which means ReVision Energy has spent a lot of time and energy deciding on which types of inverters to install for our solar customers.
There are three options available: string inverters, microinverters, and power optimizers.
There are several differences between the three types of inverters, and each has its own set of pros and cons. Let's dive into the details of string inverters, microinverters, and power optimizers, and how they work in a solar power system.
String inverters, which are the standard inverter style, have one centralized inverter — one central exchange station. This design works well when solar panel outputs are closely matched, and to this day they're our preferred choice for exterior ground-mounted arrays in open fields with full solar access. However, they are not necessarily resilient in situations with partial shading. Sort of like old school Christmas lights, where if a single bulb went out, the entire set of lights would stop working - if a single solar panel is shaded in an array with a string inverter system, it significantly reduces the output of the entire string.
Modern string inverters actually deal with this issue much better than older models thanks to a technology that includes multiple Maximum Power Point Tracking (MPPT) inputs per inverter, but we'll save that for the topic of another day.
String inverters are standard in the industry, and they’re the least expensive.
Microinverters are small, individual converting units built into each solar panel. Rather than have the 'add up the string into one whole' model like with String inverters, each solar panel was essentially its own independent system. Hence the 'micro' name.
The motivation for building this type of inverter technology was to solve for a situation when the array experiences mixed lighting (for example, during the day a large tree casts a shadow across of your solar panels). Microinverters allow for the entire array to be more consistent and continue to generate energy while one or several inverters are not working.
Unfortunately, the promise of microinverters was also severely impacted by equipment failures in the early generations. Sort of obviously - with a string inverter, though it may seem like "hmm you have one inverter if that goes down your whole system turns off" - it actually proves that putting a single piece of equipment in an accessible location protected from extreme temperatures is far easier on the equipment than having them be installed on the bottom-side of solar panels, where temperatures can exceed 140 degrees Fahrenheit, as microinverters are.
While microinverters have gotten better since the early generations (and to their credit Enphase has stood behind their product and helped us help our customers who were affected by early warranty claims), the basic logic remains that having more equipment on your roof means your solar array has more points of failure.
Microinverters tend to be more expensive than other inverter options.
Power optimizers are somewhere in between string inverters and micro-inverters both in how they function and in price. They are essentially string inverters with module-level electronics.
A Power Optimizer system allows for panel-level monitoring and power regulation as with a microinverter, but the transition of energy from DC to AC still happens at a central SolarEdge string inverter. This is accomplished with individual power optimizers that are attached to each panel via the racking, as seen in the photo.
Around 2011, new fire codes were adopted across Maine, New Hampshire, and Massachusetts that created a 'rapid shutdown' requirement, meaning that a solar array that is turned off during a fire event needs to discharge power within 10 seconds. String inverters, by design, took longer than 10 seconds to shut down and thus were essentially disqualified from the North American market. The module-level electronics in SolarEdge overcomes this.
The system has all the same advantages of a string inverter (overall more efficient and the 'guts' of the system protected by being in an electronics-friendly environment) with some of the same advantages of microinverters - the optimizers attach to each panel, and each panel can communicate to the whole for data monitoring purposes as well as fire code compliance. Unlike microinverters, there is less 'stuff to break' with a power optimizer design.
Cost wise, Power Optimzers fall somewhere in between String Inverters and Microinverters.
It is a no-brainer that we install primarily SolarEdge Power Optimizers as our inverters (more on that below).
ReVision Energy mainly installs SolarEdge Inverters with Power Optimizers. There are three significant benefits to this combined system:
You might be wondering why systems with Power Optimizers are so much more efficient than other inverter options? Great question. They are able to avoid loss of power caused by individual panel shading or malfunctioning, which can happen with string inverter systems.
They are more also effective than microinverters for larger systems because they are not limited by the cap of 21 microinverter panels, due to voltage regulations.
If panels are shaded, SolarEdge power optimizers reconfigure their output and combined voltage, so that an output drop in one or more panels does not impact the overall effectiveness of the entire system.
(A photo of solar array with an inverter and power optimizers on the bottom of the panels)
Additionally, SolarEdge inverters are designed to include responsive temperature and safety features, which are always important for the efficiency and longevity of any solar energy equipment (as well as the comfort and peace-of-mind of the homeowner).
Solar inverters function at full capacity in cooler temperatures. When the surrounding environment gets too warm, SolarEdge inverters decrease their current output to protect the equipment, prolonging the efficiency and lifetime of the equipment. It’s also a crucial safety feature that prevents your system from overloading.
SolarEdge inverters also include SolarEdge SafeDC™, a safety feature that automatically turns off your solar panels during a grid outage. This removes the risk of a voltage surge, electrocution, or damage to your home.
Another advantage of SolarEdge inverters is their ability to be added to, making it possible to expand your solar energy system with more solar or additional energy efficient technologies. In addition to having the option to put panels on different parts of your roof, homeowners can add another array much more easily in the future if energy needs increase.
SolarEdge inverters are also battery-ready and fully integrated with Tesla’s Powerwall, which ReVision installs for our customers’ battery storage solutions (we happen to be a Certified PowerWall Installer).
SolarEdge inverters come with a 12-year warranty, and their optimizers come with a 25-year warranty. You can also choose to extend the warranty for your inverter to 25 years at a low cost. Both warranties are on the higher end of industry standards, which generally fall between 5 and 12 years on average.
ReVision also installs microinverters from Enphase, which has led the development and roll out of top-of-line microinverters in the solar industry for years. Depending on the system and the customer's needs, we will consider Enphase for particular projects.
Our expert Solar Design team will work with you to determine the best inverter for you home energy project. Reach out to our team today to start your solar journey!
