By Keira Ray

Solar power is booming. The US solar market grew by 95% during 2016.1 While the potential of this renewable energy source is indisputable, learning the basics of residential solar power can be a stressful undertaking for potential customers. The truth is, it’s really much more straightforward than most people imagine. Solar panels are fairly simple systems, and are also customizable. This enable homeowners to tailor their solar investment to suit their unique energy needs. For homeowners looking to get a little more juice out of their solar setup, a solar power optimizer may be just the solution.

Microinverter during solar panel installation

Inverters can be installed at the system- or the module-level.

Inverters are an essential component of the home solar power system. These nifty little devices are far more powerful than they appear. Inverters are responsible for converting the energy solar panels produce from direct current (DC) electricity into alternating current (AC) electricity. Because of inverters, an entire household can run on naturally sourced electricity.

Until recently, string (or centralinverters and microinverters were the two main options for home solar customers. Central and string inverters are the most established technology. A string inverter converts electricity from multiple panels within an array. While simple in design, string inverters have power limitations and are prone to decreases in efficiency.2 Microinverters are a more recent addition to the solar power landscape, and are installed on individual panels in an array. These inverters boast improved shade intolerance issues and overall performance, but are more expensive in terms of up-front costs.3

Power optimizers are a next generation technology, and the most recent addition to high-powered solar inverters. While the functions of microinverters and power optimizers are similar, optimizers offer benefits many solar customers shouldn’t ignore.

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Power optimizers combine the benefits of microinverters with the simplicity of a string inverter.

Power optimizers are a good way to improve the efficiency of a residential solar system. Optimizers are installed at each individual panel, similar to a microinverter. However, the job of an optimizer is not to convert power from DC to AC—rather, optimizers treat the direct current so that it’s more efficiently converted by a string inverter. DC power optimizers operate at 98% efficiency, which makes them slightly more efficient than microinverters (which typically lose around 4% of their energy as heat).4

Power optimizers also help address an issue known as power clipping, or inverter saturation. Clipping happens when the solar panels send too much DC electricity to an inverter at one time. In response to this overload, the “saturated” inverter adjusts the incoming electricity in order to reduce the power of the direct current.5 While power clipping helps preserve the integrity of the solar system components, it also results in lost energy that may otherwise have used to power a home.6

Compared to central and string inverters, Module Level Power Electronics (MLPEs) like microinverters and power optimizers are safer, harvest more energy, and offer the flexibility essential for efficient repair and replacement needs.7 Power optimizers, however, are less expensive than microinverters and make an excellent addition to a string inverter setup.8

solar power optimizer cables
Rooftop solar panels on tile roof

Power optimizers help homeowners get the most out of their solar panel system.

If a solar setup has a hard time delivering enough power to a household, it may be an issue of Maximum Power Point Tracking (MPPT). A power optimizer can be a simple solution to this problem.

A solar panel’s maximum power point (MPP) is the highest power output that a panel is able to produce under various conditions.9 At the MPP, the solar electricity’s voltage and current are working in tandem at their most effective rate, and generate the most power. Voltage is a term for the attraction and repulsion forces inherent in electrical energy,10 whereas a current is the movement of electricity through a circuit (measured in amps).11 Power optimizers help panels operate at their MPP by steadily monitoring the resistance in the electric current, and adjusting the voltage and amperage in order to reach optimum power output.12

Power optimizers give residential solar arrays a major power boost.

Microinverters and power optimizers are currently competitive as far as upfront market cost. The long-term value of each module-level technology, however, depends on a homeowner’s unique system requirements and financial goals. The truth about home solar is that a qualified solar installer can help homeowners determine which type of electric conversion component will be best-suited to the situation. For solar customers looking to get every last drop of electric potential from their panels, power optimizers are a valuable addition to a solar setup.

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Bibliography

  1. Munsell, Mike. “US Solar Market Grows 95% in 2016, Smashes Records.” Greentech Media. Wood Mackenzie, 15 Feb. 2017. Web. 21 Feb. 2017.
  2. Green, Dino. “Micro-inverters vs. String Inverters – Which Is Better?” Renewable Green Energy Power. RGEP, 30 Mar. 2013. Web. 21 Feb. 2017.
  3. Maehlum, Mathias Aarre. “Micro-Inverters vs. Central Inverters.” Energy Informative. Energy Informative, 12 Sept. 2014. Web. 21 Feb. 2017.
  4. Clover, Ian. “Microinverters vs. Optimizers.” PV Magazine 1 Oct. 2014: n. pag. PV-Magazine.com. PV Magazine International. Web. 21 Feb. 2017.
  5. Sandia Corporation. “Inverter Saturation or “Clipping”.” PV Performance Modeling Collaborative. United States Department of Energy, n.d. Web. 21 Feb. 2017.
  6. Grana, Paul. “Solar Inverters and Clipping: What DC/AC Inverter Load Ratio Is Ideal?” Solar Power World Online. WTWH Media, LLC, 18 Aug. 2016. Web. 21 Feb. 2017.
  7. Clover, Ian. “Microinverters vs. Optimizers.” PV Magazine 1 Oct. 2014: n. pag. PV-Magazine.com. PV Magazine International. Web. 21 Feb. 2017.
  8. Clover, Ian. “Microinverters vs. Optimizers.” PV Magazine 1 Oct. 2014: n. pag. PV-Magazine.com. PV Magazine International. Web. 21 Feb. 2017.
  9. College of Engineering and Applied Science. “Maximum Power Point – Lesson.” TeachEngineering.org. University of Colorado Boulder, n.d. Web. 22 Feb. 2017
  10. Beaty, William J. “What Is Voltage?” Amasci.com. Bill Beaty, 1998. Web. 22 Feb. 2017.
  11. Lucas, Jim. “What Is Electric Current?” LiveScience. Purch Media, 29 Feb. 2016. Web. 22 Feb. 2017.
  12. Zipp, Kathie. “How Do Power Optimizers Help Harvest More Energy from Solar Projects?” Solar Power World. WTWH Media, LLC, 07 Jan. 2016. Web. 22 Feb. 2017.

Editor: Kelsey Tollefson

Executive Editor: John Lenker