Solar Equipment Innovations: Page 3 of 5

Intermediate

Inside this Article

Larger PV module can mean less installation time and expense
While a little more difficult to handle because of its physical size, a larger PV module can mean less installation time and expense.
Glass-on-glass modules
Some glass-on-glass modules allow light to pass through or between cells, creating a pleasant ambience beneath and the possibility of collecting more light reflecting up from below.
Glass-on-glass module from Trina Solar
This glass-on-glass module from Trina Solar offers a Class A fire rating.
SolarWorld’s Sunmodule Protect glass-on-glass module
SolarWorld’s Sunmodule Protect glass-on-glass module offers improved reliability (it’s less prone to water intrusion and cell breakage) and a 30-year linear performance guarantee.
Enphase Energy Microinverter
Microinverters offer module-level multiple power point tracking, monitoring, and simplified array design.
Power-One's Aurora Microinverter
Microinverters offer module-level multiple power point tracking, monitoring, and simplified array design.
AC modules
AC modules have microinverters pre-attached, providing the same benefits as microinverter installations, but reducing installation time and complexity.
Transformerless inverter
Transformerless inverters offer more safety features, as well as higher efficiency and lower weight.
SMA America’s Sunny Boy TL series
SMA America’s Sunny Boy TL series with Secure Power Supply is the first grid-tied inverter that can provide limited PV-direct power during a grid outage—without battery backup.
High-voltage charge controller
High-voltage charge controllers enable the use of smaller-diameter wire from the array to the controller, and the ability to use a wider range of higher-voltage modules in the system.
Railless mounting
Railless mounting decreases the time, materials, and cost of mounting PV arrays,
Auto-ground solutions
Auto-ground solutions - like the dimpled disk which scratches through the anodization on the aluminum module frame to electrically bond it to the adjacent module via the disk - decreases the time, materials, and cost of mounting PV arrays.
Fronius IG Plus inverter
Some inverters, such as this Fronius IG Plus, now provide arc-fault protection, as required by the 2011 NEC.
Screening underneath an array provides an additional measure of system protection.
Screening or mesh that keeps critters out from underneath an array provides an additional measure of system protection.
Wire management solutions
Proper wire management is key to professional-looking installations, and helps ensure that wiring stays safe and secure.
Wire management solutions
Proper wire management is key to professional-looking installations, and helps ensure that wiring stays safe and secure.
Larger PV module can mean less installation time and expense
Glass-on-glass modules
Glass-on-glass module from Trina Solar
SolarWorld’s Sunmodule Protect glass-on-glass module
Enphase Energy Microinverter
Power-One's Aurora Microinverter
AC modules
Transformerless inverter
SMA America’s Sunny Boy TL series
High-voltage charge controller
Railless mounting
Auto-ground solutions
Fronius IG Plus inverter
Screening underneath an array provides an additional measure of system protection.
Wire management solutions
Wire management solutions

AC modules and microinverters share many characteristics, but they are different from both an National Electrical Code (NEC) and an installation perspective. Microinverters are field-installed, one inverter per module, while AC modules have factory-integrated inverters and have one warranty for the complete assembly. AC modules are listed to both UL standard 1741 (for inverters) and UL 1703 (for PV modules). AC modules generally have a standard 25-year performance warranty, like PV modules, while microinverter warranties vary from 10 to 25 years.

There are only a few microinverters currently available in the United States. Those include Enecsys’ Gen 240/300-60-MP, in 240 and 300 W AC output power versions, that can be paired with 60-cell modules; Enphase Energy’s M215 and M250 models, producing 215 W or 250 W AC output power, which are also compatible with 60-cell modules; PowerOne’s Aurora microinverter (250 W or 300 W versions, which accommodate 60-, 72-, and 96-cell modules); and SMA America’s Sunny Boy 240-US (used with 60-cell modules; see “Gear” in this issue).

AC modules are available from Canadian Solar, ET Solar, Mage Solar, SunPower, Talesun, and Westinghouse Solar. The microinverter that is part of an AC module is usually made by a third party (like SolarBridge Technologies) but is typically sold under the module manufacturer’s label. For information about AC modules and the NEC, see “Code Corner” in this issue.

Inverter Innovations

Higher-Efficiency Inverters

Grid-tied string inverters are more efficient than ever. Go Solar California’s eligible equipment list (gosolarcalifornia.org) includes more than 30 models with a weighted efficiency value of 98% or greater. Inverters operate more or less efficiently at different power output levels, so weighted efficiency is an average across a range of power, with estimated percentage of time spent in a given power range factored into the equation. Model specification sheets list “peak efficiency” as a higher value than weighted efficiency, as peak efficiency is the highest efficiency an inverter can reach, regardless of power output. 

One technological development that helps increase efficiencies is the move to transformerless inverters (also called nonisolated inverters). Instead of relying on an iron-core or high-efficiency transformer, transformerless inverters convert DC to AC through rapid electronic switching, with no isolation between the DC and AC conductors. These inverters are not only more efficient, but weigh less and feature superior ground-fault protection that detects faults more reliably and at lower current levels. Some can be enabled to check the insulation resistance of DC conductors each day before beginning operation—helping reduce the potential of fires due to undetected ground faults. Some, including SMA America’s transformerless inverters, include DC arc-fault protection, as required in the 2011 NEC.

Many inverter manufacturers are offering these inverters, often distinguished by “TL” in the model number. Although neither current-carrying conductor on the DC side is bonded to ground (there’s no DC system ground or DC grounding electrode conductor necessary), they still must have all of the equipment grounding required of any PV array (see “Ungrounded PV Systems” in HP150). The fourth-generation Enphase M250 is an ungrounded microinverter and does not require a DC-grounding electrode conductor.

Daytime Solar Backup

SMA America’s new Secure Power Supply (SPS) feature is available on SB 3000, 4000, and 5000 TL-US inverters. In the past, capturing power from a utility-interactive array during a power outage was only possible if the system had a battery bank and inverter with stand-alone capabilities. While SMA’s SPS-enabled inverters are primarily utility-interactive, each includes a manually switched outlet that allows stand-alone daytime power during utility outages. When the sun is shining at a high-enough irradiance level, the inverter can provide up to 1,500 watts through the outlet. The power supply can be used for small appliances or to charge cellphones or computers, but there is no energy storage for use at night or during cloudy weather. The amount of power available will fluctuate based on the sun’s intensity on the array.

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