Designing Multi-Tenant and Multi-Home Developments with Enphase Microinverters

Transcription

1 TECHNICAL BRIEF Designing Multi-Tenant and Multi-Home Developments with Enphase Microinverters Overview Enphase Energy s Microinverter system is the ideal solar electric solution for new home developments, existing retrofit developments, and multi-tenant housing projects. Due to the flexibility in design that Enphase Microinverters offer, they are particularly suited for these applications. This document discusses the design considerations that are particular to using Enphase in applications with multiple Envoy Communication Gateways installed on a common utility transformer, such as new home developments, multi-tenant projects, and high density retrofit construction projects. The Enphase system is unique from other systems because all of the wiring is 240VAC or 208VAC, which can be installed by any competent electrician without additional special training. The microinverters convert DC power to AC power with high efficiency. The system also enables module-level monitoring of the production from the Enphase Enlighten website. The system is reliable and easy to install but requires a few special considerations to ensure a successful project with robust communications between the microinverters and the Envoy. The purpose of this document is to give an overview of the design, installation, and commissioning processes for homebuilders, developers, and integrators to use when installing Enphase in new and existing communities. General Considerations for All Applications Keys to Success AC power distribution Locating the Envoy Commissioning multiple Envoys Mounting the Envoy outdoors Network configurations of the Envoy Activating the system in Enlighten Specific Applications Covered New home developments Multiple homes on a common transformer Typical multi-tenant buildings with distributed interconnection points Multi-tenant buildings with a common point of interconnection Multi-tenant projects with more than 500 microinverters For commercial scale, multi-tenant systems that feed a single electric meter, best practices are detailed in a separate document, Enphase Application Note: Commercial System Design for M215, available at: 1

2 Sample Electrical Schematic for a Typical Installation Keys to Success Observe the following key considerations to ensure project success. We will come back to these two concepts throughout the document. 1. Install a dedicated Envoy receptacle on a dedicated branch circuit. While not required, this will help to ensure robust Power Line Communications (PLC) between the Envoy and the microinverters. This dedicated Envoy branch circuit should be wired directly from the solar load center or at the load center that contains the microinverter output circuits. 2. Turn on each system individually and disable the Device Scan before commissioning another system on the same utility transformer. When multiple Envoys are located on a single utility transformer, take precautions to ensure that each Envoy s database is populated only with the microinverter serial numbers in that communication domain. You can best do this by commissioning each Envoy and it s associated system separately. After commissioning each system, be sure to use the Envoy to Disable the Device Scan before commissioning another system. (See the step-by-step procedure in Commissioning Multiple Envoys on page 12 for more details.) 2

3 AC Power Distribution The AC wiring and components required for an Enphase system are readily available from hardware stores and electrical supply houses. The microinverter output circuits will generally terminate in the resident service panel, but for systems with multiple branch circuits, a solar subpanel can be used to combine the circuits first. If a solar load center is used, it can be installed near the main service panel but it may be advantageous for PLC signal strength to install it in a location near the Envoy and/or network enclosure. Locating the Envoy In most applications, the PLC can work reliably for distances up to 250 feet. However, when the PV system and the Envoy are isolated from the site loads, the Envoy and microinverters can communicate at distances greater than 500 feet. Site loads can affect the impedance of the wiring and can add electrical noise. These factors can have a significant impact on PLC. To ensure quality PLC between the Enphase microinverters and the Envoy, we recommend installing a dedicated circuit to feed the Envoy. This simple step can greatly improve the PLC by separating the communication signals from the site loads. An arc fault (AFCI) breaker can feed this receptacle. The dedicated Envoy receptacle can be installed by the broadband router or at another convenient location. The Envoy can be installed in the residence or in an outdoor-rated box. If the Envoy is not located near the router, then an alternate network connection must be made between the Envoy and the router. To do this, you can use a hardwired CAT5/CAT6 connection, an Ethernet bridge, or aftermarket wireless components. A variety of networking solutions are discussed later in this document. (See Network Configuration of the Envoy Gateway on page 14.) 3

4 Special Considerations for New Home Developments In new construction projects, homebuilders will frequently install a dedicated Envoy receptacle near the network distribution system at a convenient location for mounting the Envoy. If a solar load center is installed, the Envoy receptacle can be wired directly from that load center. In a new construction project, there is the advantage of being able to run the networking and electrical wiring in the walls while they are still open. This makes it very practical to run Type NM cables (non-metallic cable, i.e., Romex) in the walls and attic for the microinverter output circuits and for a dedicated Envoy receptacle. SolaDeck rooftop combiner boxes can provide for a quick transition from the Enphase cabling to the nonmetallic cabling. Sample Electrical Schematic for Residential New Construction 4

5 Considerations for High Density Retrofit Projects Multiple Homes on a Common Transformer When installing multiple Enphase systems and multiple Envoys in a single neighborhood and on a common utility transformer, you must make sure that the systems are commissioned individually and that the Envoy s seven-day device scan is disabled after commissioning. This is because the communications signals can travel between residences being fed by a common utility transformer. Disabling the device scan prevents neighboring microinverter serial numbers from populating the Envoy s database. (See the step-by-step procedure in Mounting the Envoy Outdoors in a Custom Enclosure on page 13 for more details.) For retrofit construction, it is most common to run the conduit on outside of the house. For these applications, most integrators will install the Envoy at the broadband router. When the Envoy is first plugged in to a receptacle, it reports the communication strength within a few minutes. If the communication strength shows two bars or fewer, another location should be tried. If it is difficult to find a good location, a dedicated Envoy in an outdoor rated enclosure will generally ensure good PLC between the Envoy and the microinverters. (See the step-by-step procedure in Commissioning Multiple Envoys on page 12 for more details.) Sample Electrical Schematic for High Density Residential Retrofits 5

6 Multi-Tenant Developments up to 100kW With Distributed Points of Interconnection This section discusses the best practices for installing a multi-tenant photovoltaic generation system that feeds multiple residence service meters or subpanels. In addition, these meters or subpanels are distributed across the project at each tenant residence. In this scenario, the modules can be installed as one large array or multiple smaller arrays, but the microinverter output circuits feed the distributed meters or tenant subpanels as multiple smaller systems. In these applications, it is best practice to terminate the microinverter output circuits at the tenant subpanels. This reduces the amount of wiring needed to interconnect the systems to the existing electrical system. A separate Envoy should be installed at each residence subpanel. If the microinverter output circuits are tied to the existing tenant load centers, a separate Envoy or LCF must used at each tenant load center. 6

7 Sample Electrical Schematic for Multi-Tenant Installations with Multiple Systems Back-Feeding Multiple Service Meters at Distributed Locations 7

8 Multi-Tenant Developments up to 100kW With the Microinverter Output Circuits all Terminating at a Common Location This section discusses the best practices for installing a multi-tenant photovoltaic generation system that feeds multiple residence service meters at a single location. In this scenario, separate sub-arrays feed the multiple tenant meters. In these systems, a single Envoy may be able to monitor the entire multi-tenant building or a cluster of meters that are co-located. One case where this can work is when the microinverter output circuits are all terminated at a common meter location, as shown in the following image. If the meters are installed on a common utility transformer, the communication signals will likely pass between the meters, and a single Envoy can be used to monitor multiple systems. This will work best when the Envoy is co-located at the meters location and all the systems microinverters are located with 200 ft. of wire length from the Envoy. A single Envoy can monitor up to 500 microinverters. If multiple Envoys are used on a common utility transformer, it is important to turn on each Envoy and its related system individually and to disable the device scan before commissioning another Envoy and system. (See the step-by-step procedure in Commissioning Multiple Envoys on page 12 for more details.) 8

9 Sample Electrical Schematic for Multi-Tenant Developments Up to 100kW with Multiple Systems Terminating at a Common Point of Interconnection 9

10 Multi-Tenant Developments over 100kW This section discusses the best practices for installing a multi-tenant photovoltaic generation system with more than 500 microinverters on a common utility transformer. Some special considerations must be taken into account to ensure reliable communications. A single Envoy can monitor up to 500 microinverters. With more than 500, monitoring is adversely affected. In systems with more than 500 microinverters, separate communication domains must be set up. The separate Envoy communication domains must be equipped with Line Communication Filters (LCFs) or with transformers. Since using transformers is not practical in most multi-tenant applications, LCFs are the best solution. Designing with Line Communication Filters The LCF isolates the communication domains from each other. The LCF includes an Envoy inside and is rated for outdoor installations. The Envoy is powered directly by the LCF s utility input, removing the need to install a dedicated receptacle for the Envoy. Installing an LCF requires that the PV system microinverters are wired into the PV input side of the LCF (on the right side). The LCF is rated for a maximum of 100A of continuous current and can be fed by a 125A circuit breaker or over-current protective device (OCPD). The 125A rating is a limiting factor when designing systems with LCFs. The LCFs 125A rating impacts where it is located and how many microinverters can be installed on it. See the following table for details on the number of microinverters that can be installed on an LCF. Multi-tenant systems greater than 100kW may require a separate LCF for each electric service meter. Enphase offers free design review services to assist you in designing commercial and multitenant projects. Reach out to your Enphase account representative or contact Enphase at Microinverter Model Maximum Number of Microinverters per 125A LCF Microinverter Watts System Voltage Microinverters per LCF M at M at M M M M AC System Size in kw 10

11 Sample Electrical Schematic for Multi-Tenant Installations Greater than 100kW with Line Communication Filters on each Electric Service Meter 11

12 Commissioning Multiple Envoys Properly commissioning the Envoys is critical to the success of the project. The Envoy should be installed and connected to the Internet about an hour before the installation is completed and before the microinverters are producing power. If multiple Enphase systems are being installed in the same neighborhood and on the same utility transformer, take care to ensure that only one system is commissioned at a time. Follow these steps to commission the Envoy in a multi-envoy environment: 1. Plug in the Envoy to a standard, 120Vac receptacle 2. Plug in the Local Area Network connection to the Envoy and verify that the green link light on the back of the Envoy is illuminated. 3. The Envoy should display +Web after four or five minutes. 4. Once the Envoy has connected to the Web, it will automatically update its software. Do not unplug the Envoy during this time. The Envoy display will display Upgrading Do Not Unplug. The software update will last for 30 minutes or longer, depending on the connection speed and software version. The Envoy will display -Web for about two minutes after the new software has been updated, but should quickly return to +Web. 5. Upon startup, the Envoy will begin a seven-day device scan for new devices. If it detects any devices in the first hour before the solar array is powered on, they have been "poached" from a neighboring system. Use a laptop to access the Envoy Device Conditions and Controls menu and delete them, or contact Enphase Customer Support at support@enphaseenergy.com. 6. Once the installation is complete and all electrical panels and junction boxes have been properly closed and covered, turn on the photovoltaic system that is associated with this Envoy. The Envoy should now begin to populate its database with the microinverters on site. This generally takes about 20 minutes, but can take longer. This will not work at night as the microinverters operate only during daylight hours. (They are powered on by DC solar power.) 7. Once the Envoy has populated its database with all of the microinverters at the site, hold down the menu button on the right side of the Envoy until the display reads Disable New Device Scan. A new device scan should never be allowed to run for the default seven days, because it will be able to poach neighboring microinverters when they first power-up each morning. Once the device scan has been disabled, you can now move to commissioning another Envoy in the community. 8. As an additional precaution, you can send a request to Enphase Customer Support at support@enphaseenergy.com to Inhibit Device Scanning at the site so that no further device scans can be run by the site owner. 12

13 Mounting the Envoy Outdoors in a Custom Enclosure When mounting an Envoy in an outdoor location, use an LCF or a custom enclosure. When installing the Envoy in an outdoor location, use an outdoor rated electrical enclosure. This custom enclosure must be large enough to house the Envoy and a dedicated receptacle to power the Envoy. The enclosure can be metal or PVC. You can also locate an Ethernet bridge, wireless bridge, or other networking components in this enclosure. The Envoy s outdoor enclosure must meet the following requirements: NEMA 4 outdoor rated enclosure, metal or PVC. One possible solution would be a Cantex Enclosure, Part# Minimum recommended dimensions of 12 x 12 x 4 Contains a GFCI receptacle, installed in a 1-gang metal box and with a cover. The GFCI should be fed by a 15A OCPD and minimum #14 conductors (as per NEC). Ideally, the enclosure should be in a location that is shaded from midday sun. However, the Envoy is rated for environments up to 65 C / 149 F. 13

14 Network Configuration of the Envoy Gateway With all Enphase installations, communication between the array and the Envoy is key to system monitoring and maintenance. The Envoy communicates with the microinverters in the solar array via the premises power line wiring. The Envoy also communicates with Enlighten site via its LAN (Local Area Network) cable, connected to the premises broadband Internet connection. The Envoy, in this sense, acts just like another computer in the house or business, connecting through a standard Ethernet LAN cable and using standard TCP/IP protocols. While it is a trivial task to make this connection in a single residence, a multi-residence installation requires additional considerations. 14

15 Typical Network Setups Typical Ethernet Network Topology: Type 1 with Enphase Envoy In a typical residential networking setup, the LAN (Local Area Network) portion is what is on the inside of the local network. In the diagram below, that would encompass Computer-A, Computer-B, the Envoy and the router. The WAN (Wide Area Network) portion is what is on the outside of the local network. In the diagram above, that would encompass the WAN port of the router and the DSL/cable modem. The WAN is the upstream connection to the Internet. The router may also include wireless (WiFi) services, and there may be one or more laptop computers in the residence that access that router via WiFi. 15

16 Typical Ethernet Network Topology: Type 2 The typical LAN/WAN setup is a little more involved, but the components are the same. The diagram below reflects a typical small network design. The computers are connected to the Network Switch via standard Ethernet cables. The computers with wireless (WiFi) capability access the LAN via a separate wireless access point, which itself is connected to the network switch. The network switch is connected upstream to the router. The router then plugs into the wall plate where the business has a DSL or T1 connection to the Internet. 16

17 Using Ethernet Bridges with the Enphase Envoy Envoy-to-LAN In the event that wired LAN connectivity is not available in the room where the Envoy is placed (to maximize Envoy-to-microinverter communications) then a pair of Ethernet Bridges can be used. These are commonly referred to as home plugs. The pair of home plugs allows the Envoy to connect back to the broadband router without the need for additional Ethernet cabling. Making the Connection 1. Place the Envoy in a location that is near the load center. Plug the Envoy s power cord directly into an electrical wall socket. (Do not use a UPS battery backup or a power strip.) 2. Plug one of the home plug devices into the same wall socket as the Envoy s power cord. 3. Connect one end of the Ethernet LAN cable into the network connection on the Envoy. Connect the other end of that LAN cable into the home plug. 4. Plug the other home plug into a wall-socket near the broadband router. 5. Connect one end of a second Ethernet LAN cable into that second home plug. Connect the other end of that LAN cable into the broadband router. Reference the diagram: 17

18 Typical Enphase Energy Multi-Tenant Deployment: Multiple LCFs For large multi-tenant and commercial projects, use multiple LCFs to isolate the Envoys from each other. In this scenario, each of the Envoys communicates (via the power lines) with its own collection of microinverters. Each collection of microinverters is called a communications domain. The following diagram shows two LCFs, each with their own microinverters and attached photovoltaic (PV) modules. This model can scale as large as you need. For another collection of fewer than 500 microinverters, add another LCF with built-in Envoy to build discrete groups (LCF+Envoy+Microinverters) each in their own communications domain. Using the filtering mechanism of the LCF, the power line communications from one communications domain is isolated and separated from any others. 18

19 Multi-Tenant Deployment with an Ethernet Network using a Wireless LAN The installer may want to use a wireless access point to provide Internet connectivity to one or more of the Envoys and/or LCFs. In this scenario, only the wireless access point needs the hard-wired connection to an Internet switch/router. In turn, it provides WiFi services to each of the Envoys. The Envoy does not have wireless capability built in, so each requires its own wireless Ethernet bridge to pass data from the Envoy to the wireless access point as shown in the following diagram. 19

20 Wireless Technologies Consumer-grade WiFi devices have varying ranges of operation. Not all WiFi vendors specify the unobstructed distance for which their product will provide wireless coverage. Wireless specification g is the current standard, with n recently ratified. Check vendor specifications for claims of distance/coverage, and remember to factor in obstructions, such as buildings, walls, etc. Wireless Vendors: Linksys: Netgear: Ubiquity Networks: Meraki: Wireless Routers WiFi routers provide a wireless gateway to the Internet. Wireless vendors Linksys and Netgear produce WiFi routers that are installed in large numbers and that are solid and reliable. Units come with installation DVDs and software for easy setup, have excellent documentation, and come with phone or online technical support. Wireless Ethernet Bridges A wireless Ethernet bridge converts a wired Ethernet device for use on a wireless network. (Think of it as an external wireless network card). The Linksys WET610N and Netgear WNCE2001 are often recommended. 20

21 Wireless Hi-Gain Antenna Systems for Long Distance Communications Wireless Hi-Gain Antenna systems are for use when the distance from the Envoy or LCF to a wireless router is over 500 feet. Ubiquity Networks directional Nanostation 2 is recommended. The system is made for outdoor use, and a variety of mounting brackets are available. Configuration is accomplished through a web interface, and a number of tools are available to verify signal strength between devices. 21

22 Wireless Mesh Network A wireless mesh network is a communications network made up of multiple wireless bridges and antennas organized in a mesh topology. This topology would be used at sites with multiple buildings, where cabling would be extremely difficult. Ubiquity Networks makes a weatherproof Nanostation 2 with PicoStation M units. Meraki Networks also makes a weatherproof unit called the OD2, which is an Omni-directional WiFi access point. The OD2 can to connect an LCF and transmit a signal to extend reach to other OD2 devices. 22

23 Network Basics and Troubleshooting DHCP and Self Assigned IP Address ( x.x) When the Envoy first boots up, it is configured to perform a DHCP (Dynamic Host Configuration Protocol) broadcast, requesting an IP address from a DHCP source. This source can be a server/computer, but almost all consumer-grade broadband routers also provide DHCP services as well, and this is the usual source of IP addresses for network hosts (computers, laptops, and the Envoy). If the LCD window of the Envoy displays an IP address beginning with , this means that the Envoy was unable to receive an IP address from a DHCP source, and so it assigned this address to itself. Check the Ethernet cabling and check that the router is providing DHCP services. DHCP versus Static IP Addressing If the site owner prefers not to use DHCP, the Envoy can be set up to use a static IP address. Use the Envoy s web-interface to navigate to the ADMINISTRATION page. The Username is admin, and password is admin. Click the Network Connectivity menu item. This allows you to see if the Envoy is using DHCP or Static-IP, and allows you to change this setting if needed. Click Check Network Connectivity to view the Envoy connections. For more information on how to use the Envoy Interface, refer to the Envoy Communications Gateway Installation and Operation Manual at WARNING: Do not change the Envoy DHCP setting to use a static IP address unless you also reserve the same IP address on your broadband router. See the section on DHCP Reservations in your router's setup manual. Failure to reserve the static IP address on the router will result in duplicate IP addresses and intermittent Internet connection problems with your Envoy. MAC Filtering Check to see if MAC Filtering is in use at the site. This has nothing to do with Apple Macintosh computers, but rather, refers to the MAC (Media Access Control) address that each individual network card possesses. The MAC Address is a 48-bit address that uniquely identifies that piece of hardware. MAC Filtering, then, is a security mechanism by which routers allow administrators to specify which devices can use the router for access to the Internet. This prevents unauthorized devices from using your router to get to the Internet. An example of a MAC address would be: 00:17:F2:D6:B1:45 MAC addresses contain six (6) pairs of characters, including any number 0-9 and letters A-F. The MAC address of the Envoy will begin with: 00:D0:69:41: You will need to identify the specific MAC address of the Envoy so that you can add it to list of authorized devices on the router. To do this, browse to the home page of the Envoy s web-service using an ordinary web-browser. The home page contains that specific Envoy s MAC address. The MAC address is also printed on a sticker on the back of the Envoy. 23

24 Firewall Settings The Envoy initiates outbound connections to Internet servers. Such connections may be restricted by firewall rules set up on the site s broadband router. Broadband routers typically allow all outbound connections but restrict any/all inbound connections. If outbound firewall rules are applied at the site, you must configure a static IP address for the Envoy and add new rules that allow outbound access as follows: Direction Source Protocol Port Destination OUT <Envoy IP address> TCP 443 reports.enphaseenergy.com OUT <Envoy IP address> TCP 443 securereports.enphaseenergy.com OUT <Envoy IP address> TCP 443 home.enphaseenergy.com OUT <Envoy IP address> UDP 123 us.pool.ntp.org The Envoy connects to these servers using their DNS names. If you add firewall rules for Envoy reporting, Enphase recommends using the DNS names rather than the underlying IP addresses. This is because the IP addresses are subject to change without notice. WARNING: Do not change the Envoy DHCP setting to use a static IP address unless you also reserve the same IP address on your broadband router. See the section on DHCP Reservations in your router's setup manual. Failure to reserve the static IP address on the router will result in duplicate IP addresses and intermittent Internet connection problems with your Envoy. 24