Enphase make micro-inverters (and associated cable and monitoring equipment) that convert the DC generated by PV panels into AC hydro power that we can use in our homes. They publish a series of technical bulletins describing the various components of their systems.The most important technical brief describes methods for calculating the AC line voltage drop (or voltage rise) and presents voltage rise guidelines for dedicated PV branch circuits using M215/M250 micro-inverters and Engage cable.
The application of proper voltage rise calculations in your site plan will help to prevent nuisance trip issues due to high line voltage conditions. Moreover, less resistance in the wiring results in less heat at the terminals, less power loss, and improved performance of the PV system.
These calculations are commonly called voltage drop (VDrop) calculations, but PV systems generate electricity and voltage actually rises at the AC terminals of microinverters. Voltage rises because microinverters are a current source rather than a voltage source or a load. This brief refers to these calculations as voltage rise (VRise).
The full document, which you should make sure your electrician reads if they are not an Enphase certified installer, can be downloaded from: EnphaseTechBrief_Vdrop_M215
I have prepared a quick summary at: http://www.solarinstalls.info/cable-sizing-and-length/
Apart from this, there are many other documents that users of Enphase systems and components might find of use, all are in .pdf format. They used to be accessed from the Enphase site, but I can no longer find them there, so I have uploaded copies I downloaded and saved some years ago. Please note there may well be more up to date versions, if you know of any please let us know!
Since the inverters ‘talk’ to the Envoy through the power cables, it is possible that other items in your house, such as motors, dimmers, intercoms that ‘talk’ through the house wiring, etc could introduce enough interference onto the power line that the inverter-envoy communication link fails. It is possible to cure this by placing filters on the lines that are generating the interference. More on the subject can be found at: here.
NEW! Sept 2016
Enphase Energy Inc. has unveiled its Enphase home energy solution with IQ, which combines solar, storage and energy management.
The solution features the company’s sixth-generation Enphase IQ micro-inverter system, integrates with upcoming AC modules from LG and SolarWorld, and offers installers faster and simpler installations, according to Enphase.
The Enphase IQ 6+ Micro supports 60- and 72-cell modules up to 400 W DC, and the Enphase IQ 6 Micro pairs with modules up to 330 W DC. The company says they are 30% lighter than Enphase S-Series micro-inverters and 40% lighter than similar micro-inverters on the market – partly due to their double-insulated, non-corroding polymeric enclosure.
The company says its two-wire Enphase Q cable is 50% lighter than the previous generation of the Enphase trunk cable. The Enphase Q aggregator offers a plug-and-play connection for up to three branches on the roof, and the Enphase Q combiner provides further installation and commissioning efficiency.
In addition, says Enphase, its IQ 6 micro-inverters comply with fixed power factor, voltage and frequency ride-through requirements and meet current and known future requirements for distributed solar on utility networks, including Rule 21 in California and Hawaiian Electric Co. Rule 14H.
The IQ family, like all previous Enphase micro-inverters, is fully compliant with NEC 2014 and 2017 rapid shutdown requirements. Unlike string inverters, this capability is built-in and requires no additional equipment, the company says.
The Enphase IQ 6 micro-inverter system is expected to be available in North America in the first quarter of 2017.