Solar Inverters Explained

by HE Solar LLC

black and white photo of a solar inverter and electrical switchgear on a wall

Solar inverters are the brain of a solar power system. Their main function is to take the DC Electricity output from solar panels and change it to AC electricity found in homes and businesses. They also provide production monitoring allowing you to monitor the systems production online!

HE Solar LLC has a reputation for only using premium solar inverters that have proven reliability. For this reason we do not use Micro Inverters or AC Solar Panels. This page will give insight into why we only use certain solar inverters.

Inverter Types

2 sma string inverters mounted on a concrete wall

String Inverters

Traditional solar inverters are incredibly reliable and are common in ground mounted solar systems.

split image of solar edge dc optimizers on a roof and a solar invert on the wall

String w/ DC Optimizers

DC Optimizers combine the benefits of String Inverters and Micro Inverters with a proven reliability.

Micro inverter mounted on a rail

Micro / AC Panels

Micro Inverters invert DC to AC directly under the solar panel. AC Panels come with built-in Micro Inverters.

he solar owner Derrick Hoffman standing next to sma battery inverters

Battery Inverters

Battery Inverters allow for backup power and other uses of energy storage in a home or business.

Get Pricing: Submissions go directly to the Hoffman Brothers... or call 512-921-6763
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Getting Started w/ Inverters

The role inverters play in a solar system

Solar customers don’t have to be experts in electricity but it does help to understand the difference between DC and AC Electricity:

DC Electricity: Solar Panels create Direct Current Electricity, a form of electricity that is also found in batteries. AA Batteries found in remote controls are a good example of DC electricity that you likely have experience with.

AC Electricity: Alternating Current Electricity is a form of electricity that we have in our homes and businesses.

Solar Inverters take the DC Electricity from solar panels and invert it into AC Electricity.


Grid Tied Solar: Follow the Energy

a line diagram showing the role an inverter plays in solar energy flow

Grid Tied Solar Inverters: Typical Line Diagram

HE Solar - Grid Tied Inverters

Side by Side Comparison

SMA 7.7-40 w/ Tigo SolarEdge 7600A Enphase IQ6+ SunPower 360 AC
Max Panel Output 475 400 Watts 280 Watts 320 Watts
Module Level Monitoring Optional Yes Yes No
Rapid Shutdown Optional Yes Yes Yes

Grid Tied Inverters

Detailed Features

String Inverters

The traditional inverters that accept the DC voltage from a “string” of solar panels and invert it into AC voltage. These inverters have fewer failure points than DC Optimizers and Micro Inverters but can no longer be used on homes or buildings. We still use them for arrays on barns, ground mounts and carports.

HE Solar LLC String Inverter Options:

SMA: SMA has long been the go to option for traditional string inverters. In 2014 new Electrical Codes were introduced that made traditional Inverters difficult to use on homes and businesses. HE Solar LLC uses SMA for arrays that aren’t on a rooftop of a home or business.

 


 

solaredge inverter and dc optimizer

(LEFT) DC Optimizer mounts under the Array; (RIGHT) String Inverter mounts on the wall.

String Inverters w/ DC Optimizers

Similar to traditional inverters but with an added component. DC Optimizers, also known as DC to DC converters, are a form of Module Level Power Electronics (MLPE). A DC optimizer is placed under every panel and allows for the voltage and current to be manipulated for multiple purposes.

DC Optimizer Features:

Module Level Monitoring: Module level monitoring is our favorite DC Optimizer feature. DC Optimizers allow consumers and the installer to monitor the performance of every solar panel.

String Inverter Reliability: DC Optimizers are wired similar to traditional string inverters and still utilize a wall mounted string inverter to change from DC to AC electricity. Changing from DC to AC (Inverting) creates heat. We do not use micro inverters because the failure rates are accelerated due to the high heat environment up on the roof.

Shade Tolerance: Solar Panels with shade can negatively effect traditional string inverters due to a lowered electrical current (Amps). DC Optimizers solve this issue by transforming the shaded panels output to match neighboring solar panels.

Multiple Orientation: DC Optimizers also allow for solar panels to face multiple directions on the same string. This is beneficial for custom homes with complex roofs.

Code Compliance: DC Optimizers allow for solar electricity to be shut off before it reaches the inverter. Traditional String Inverters can not shut down electricity leaving the solar panels until it reaches the inverter.

 

HE Solar DC Optimizer Options:

SolarEdge: Now leads the North American market for inverter sales. Their products have proven very reliable and now come standard with HE Solar Installations.

SMA w/ Tigo: SMA has a great reputation but was slow to introduce a DC converter option. They recently bought a portion of tenured DC converter manufacturer Tigo.


 

enphase micro inverter mounted to solar rackingMicro Inverters

Micro inverters are placed under the solar panels or come built-in to the frame (AC Solar Panels). These units have many similar benefits of DC optimizers but have an increased failure rate due to the heat generated during the inversion process. We believe that it is the harsh Texas heat that causes these failure rates as we have heard success stories from contractors in Colder Environments.

Micro Inverter Myths

The counter argument to the micro Inverter Salesman

Micro Inverters and AC Panels are becoming more common for large solar companies looking to simplify the installation process. Below are the counter-arguments to sales strategies used by micro-inverter companies:

Design and Installation

The Myth: That there is an advantage to micro inverters because they are plug-and-play and do not require advanced designs.

HE Solar LLC Says: Simplified components limit system size and creative design. HE Solar LLC guarantees a Master Electrician and NABCEP Certified Professional will design and install EVERY solar system so simplified components are not necessary.

 

Reliability

The Myth: Micro Inverters have no single point of failure.

HE Solar LLC Says: It is true that they have no single point of failure… instead they have MANY points of proven failures in hot climates. HE Solar LLC has been recommending Central Texas customers avoid Micro-Inverters for over 4 years. The few that we have installed have had moderate failure rates. We have seen very few failures from our SolarEdge and SMA installations.

 

Easier Maintenance

The Myth: Micro Inverters failures are easy to locate and can be resolved remotely.

HE Solar LLC Says: Module Level monitoring does make failures easy to identify and SolarEdge DC Optimizers have the same benefits.  However, we have never seen these units be resolved remotely and they almost always require a crew change the unit out.

 

Module Level Monitoring Importance

The Myth: This comes from AC Panel manufacturers that have module level monitoring capabilities but do not allow the consumer to see it.

HE Solar LLC Says: Module Level Monitoring is a must have for consumers with DC Optimizers or Micro Inverters. It offers transparency on solar panel production and performance guarantees.