APsystems Microinverters, ECU-R & APsmart RSD

APsystems DS3 and QT2 microinverters, ECU-R gateway and APsmart rapid shutdown equipment at CSE Solar USA

Microinverters
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APsmart Rapid Shutdown
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APsystems Microinverters and System Components at CSE Solar USA

APsystems builds module-level power electronics: dual-module DS3 microinverters for homes, the native three-phase QT2 for commercial roofs, the ECU gateways that commission and monitor them, and the cabling that ties a branch together. CSE Solar USA lists APsystems microinverters with the matching gateway, AC bus cable and accessories so a complete, compatible system can be ordered in one place.

APsmart is the company's separate rapid shutdown line for string and hybrid inverters. It is listed here as its own section because APsystems microinverters do not need it.

Shop APsystems Microinverters

DS3 Series: single-phase, two modules per inverter

The DS3 family is APsystems' third-generation dual-module microinverter for 240 V split-phase (and 208 V) systems. Each unit has two independent MPPT inputs, a 60 V maximum input, Staubli MC4 DC connectors, a Type 6 enclosure and encrypted ZigBee communication to the ECU. The three models differ in output, so the inverter can be matched to the module.

APsystems DS3-L 768VA dual-module microinverter

APsystems DS3-L 768VA Microinverter

768 VA, two modules with independent MPPT, up to 5 units per 20 A branch at 240 V.

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APsystems DS3 880VA dual-module microinverter

APsystems DS3 880VA Microinverter

880 VA for high-output modules, up to 4 units per 20 A branch at 240 V.

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APsystems DS3-S 640VA dual-module microinverter

APsystems DS3-S 640VA Microinverter

640 VA, up to 6 units per 20 A branch at 240 V. Currently out of stock.

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QT2 Series: native three-phase, four modules per inverter

The QT2 connects four modules to one three-phase microinverter: 1,728 VA at 208 V or 1,800 VA at 480 V, for Delta or Wye grids. It uses its own 5-wire AC bus cable and accessories. QT2 supply is limited; CSE confirms availability when your order request is reviewed, before any payment is taken.

APsystems QT2 three-phase quad microinverter

APsystems QT2-208 Three-Phase Microinverter

Native three-phase, four modules per unit, 1,728 VA at 208 V. Currently out of stock.

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APsystems Monitoring and Communication

The ECU-R (Energy Communication Unit) is the gateway between the microinverters and APsystems' EMA monitoring platform. It talks to the inverters over ZigBee, connects to the internet by Wi-Fi or Ethernet, supports up to 100 microinverters (APsystems recommends 80 or fewer per ECU) and works with DS3 and QT2 series. Installers register each microinverter and set the grid profile through the ECU, and owners see module-level production in the EMA app.

APsystems ECU-R energy communication unit gateway

APsystems ECU-R Gateway

ZigBee gateway for up to 100 microinverters with Wi-Fi and Ethernet uplink.

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APsystems Y3 AC Bus Cable

12 AWG Y3 AC bus cable, one connector drop per microinverter.

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APsmart Rapid Shutdown Solutions

For string and hybrid inverter arrays, not for APsystems microinverters. APsystems states that its microinverter systems meet the NEC 690.12 rapid shutdown requirement without additional equipment. APsmart devices add module-level rapid shutdown to arrays built on string or hybrid inverters.

An APsmart system has two parts. Module-level devices sit on the roof: one RSD-S-PLC per module, or one RSD-D per two modules. A Transmitter-PLC at the inverter sends the keep-alive signal over the DC lines; when AC power is cut, the signal stops and the array shuts down. The transmitter needs a 12 V supply and an enclosure, or the Outdoor Kit, which includes both. APsmart devices are SunSpec rapid shutdown certified; if your inverter already has a SunSpec-certified transmitter built in, an external transmitter is not used.

APsmart RSD-S-PLC module-level rapid shutdown device

APsmart RSD-S-PLC Rapid Shutdown Device

One device per module, SunSpec rapid shutdown certified, for string and hybrid inverter arrays.

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APsmart Transmitter-PLC Outdoor Kit

Single-core transmitter, IP65 enclosure and 85-264 VAC power supply in one kit.

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Build Your APsystems System

This is the bill of materials APsystems' own manuals and accessories summary describe for a residential DS3 system.

Component	How many	Why
DS3-S, DS3-L or DS3 microinverter	1 per 2 modules	Converts DC to grid AC at the module; size with the APsystems module compatibility calculator
Y3 AC bus cable	1 connector drop per microinverter	Links the microinverters of a branch into one AC output
3-wire bus cable end cap	1 per branch end	Seals the open end of the bus cable
ECU-R gateway	1 per system (up to 100 inverters)	Commissioning, grid profile, monitoring and the connection the warranty terms call for
Bus connector unlock tool	1 per job	Releases the AC connectors without damage
Y-CONN caps, DC extension cables	As needed	Cap unused cable drops; reach modules that sit farther from the inverter
2-pole branch breakers, AC junction box, racking hardware, rapid shutdown placard	Per design	Required for the installation; not made by APsystems

Rapid shutdown devices are not on this list: they are not required with APsystems microinverters.

Residential Microinverter Solutions

Model	Max continuous output	Recommended module power	Max input current	Units per 20 A branch (240 V)	Units per 30 A branch (240 V)
DS3-S	640 VA	250 to 480 W+	16 A x 2	6	9
DS3-L	768 VA	265 to 570 W+	18 A x 2	5	7
DS3	880 VA	300 to 660 W+	20 A x 2	4	6

Figures are from the APsystems DS3 Series datasheet for the USA; branch limits may vary with local requirements. Because every pair of modules has its own inverter and MPPT, shading or a fault on one pair does not pull down the rest of the array, systems can be expanded two modules at a time, and production is visible per module in the monitoring app. The DS3 datasheet lists UL 1741, UL 1741 SB, IEEE 1547, CA Rule 21 and NEC 690.11 / 690.12 compliance.

Commercial and Three-Phase Solutions

For 208 V and 480 V three-phase services, the QT2 avoids the phase-balancing work of single-phase microinverters: each unit feeds all three phases. The QT2 datasheet lists up to 5 units per 30 A branch at 208 V and up to 11 at 480 V on a 10 AWG bus. A QT2 project needs the 5-wire three-phase bus cable, the 5-wire end cap and the matching unlock tool, which are different parts from the DS3 accessories, plus an ECU for every 80 or so inverters. Tell CSE the service voltage, module model and array size and we will confirm what can be supplied.

Monitoring

With an ECU-R online, the EMA platform shows production for each module pair, flags an under-performing module and lets the installer manage grid-profile settings remotely. The ECU-R is an indoor device powered by a 5 V adapter and connects by Wi-Fi or Ethernet. For export limiting or consumption monitoring on a split-phase home, APsystems documents a solution using the ECU-R with a compatible energy meter; the ECU-C's zero-export and relay functions are documented for single-phase and three-phase systems rather than North American split-phase.

Product Documents and Resources

APsystems microinverters

Gateways, accessories and warranty

APsmart rapid shutdown

Documents open on the manufacturer's own document library. CSE Solar USA is an independent online solar equipment retailer; product names, specifications and warranty terms on this page come from APsystems' and APsmart's published documents.

APsystems Frequently Asked Questions

Which APsystems microinverter should I choose: DS3-S, DS3-L or DS3?

All three are dual-module, single-phase microinverters with two independent MPPT inputs; they differ in output. The APsystems datasheet lists the DS3-S at 640 VA (recommended modules 250 to 480 W+), the DS3-L at 768 VA (265 to 570 W+) and the DS3 at 880 VA (300 to 660 W+). Match the inverter to your module wattage with the APsystems module compatibility calculator.

How many solar panels does one APsystems microinverter handle?

A DS3-family microinverter connects two modules. A QT2 connects four modules. Each input pair has its own MPPT, so modules are tracked independently.

How many DS3 microinverters can go on one branch circuit?

At 240 V the APsystems DS3 datasheet lists up to 6 DS3-S, 5 DS3-L or 4 DS3 units on a 12 AWG branch with a 20 A breaker, and up to 9, 7 or 6 units on a 10 AWG branch with a 30 A breaker. The datasheet notes that limits may vary and local requirements apply.

Do I need an ECU-R gateway?

In practice, yes. APsystems defines a system as microinverters plus an ECU plus the EMA monitoring platform. Microinverters are registered and the grid profile is set through the ECU, and the APsystems U.S. warranty terms depend on the system being connected to the internet through an ECU.

Do APsystems microinverters need separate rapid shutdown devices?

No. APsystems states that its microinverter systems meet the rapid shutdown requirement without additional equipment, and the DS3 and QT2 manuals identify the products as PV rapid shutdown equipment conforming to NEC 690.12 when installed as directed. APsmart RSD products are for string and hybrid inverter arrays.

What is APsmart, and when do I need it?

APsmart is the rapid shutdown product line from the same company. An APsmart system uses one RSD-S-PLC per module, or one RSD-D per two modules, plus a Transmitter-PLC at the inverter. It is used with string or hybrid inverters that do not have a SunSpec rapid shutdown transmitter built in. Check the APsmart inverter compatibility list before ordering.

Can APsystems microinverters be used on three-phase commercial systems?

The QT2 is a native three-phase microinverter: 1,728 VA at 208 V or 1,800 VA at 480 V, four modules per unit, compatible with Delta and Wye grids. It uses a dedicated 5-wire AC bus cable, not the DS3 cable. Contact CSE to confirm current availability before planning a project around it.

What warranty does APsystems publish for the United States?

The current APsystems Limited Warranty for the USA lists 25 years for DS3, QT2 and QS2 microinverters, 3 years for ECU gateways and 2 years for bus cable. The document sets conditions, including continuous internet connection through an ECU and purchase through APsystems-authorized channels. Read the warranty document and confirm eligibility for your purchase before relying on it. Warranty service is provided by APsystems under its own terms.

Can I install APsystems microinverters myself?

Microinverters are grid-interactive electrical equipment. APsystems manuals require installation by qualified professionals in line with the National Electrical Code, local permitting and utility interconnection rules.

Planning an APsystems system?

Send us your module model, the number of modules and your service voltage, and CSE will put together the matching microinverters, bus cable, end caps and gateway. Call (702) 608-8385, email info@csesolarusa.com or use our contact form.