Growatt helps Guam build green energy to make "Made in China" more powerful

Guam is located at 13°26′N and 144°43′E. It is an island at the southern end of the Mariana Islands in the Pacific Ocean. It has an area of ​​549 square kilometers and a population of 158,000 (2002). Guam has a tropical monsoon climate with pleasant weather all year round and an average temperature of 27 degrees Celsius. Similar to many Pacific islands, Guam has no fossil energy and must be transported by sea. The island lacks electricity supply and electricity is expensive. Ordinary residents have a tiered electricity price, and normal electricity consumption is about US$0.25 per kilowatt-hour, equivalent to RMB 1.75 per kilowatt-hour. Building solar energy projects not only has high returns, but also reduces Guam's dependence on imported fuel.

★Guam is an overseas territory of the United States. Its power grid structure is the same as that of the United States. There are two low-voltage power grid voltage systems:

1. Split Phase system, single phase three wire, voltage is 120/240V; 2. Delta 3 Phase system 480/277V and 240/120V three phase four wire system, frequency is 60Hz.

Guam has very strict product certification. All accessories, including photovoltaic modules, inverters, cables, connectors and other products that need to be installed on site, must have US UL certification regulations. The standard for photovoltaic modules in the United States is UL1703, and the US safety standard for grid-connected inverters is UL1741. Unlike China and Europe, Guam's photovoltaic inverters are not allowed to use quick connectors such as DC MC4 and AC aviation plugs. A junction box is required, and the wiring terminals are used with screws to install and fix the cables. The photovoltaic system also needs to be equipped with a quick shutdown device.

The general voltage for household appliances in Guam is 120V, but most of the distribution boxes entering the house use the Split Phase system, which means there are two live wires, and the voltage between them is 240V.

▲240V Split Phase System

The above picture shows the connection method between Growatt single-phase inverter and Guam Split Phase system power grid. The inverter models include Growatt 1.5-3K-US, Growatt3.6-5K MTL-US, Growatt4-7.6K MTLP-US, Growatt8-11K MTL-US, etc. These products have passed UL1741, UL1998, IEEE1547, CSA C222 No107 1-1, FCC Part 15 (Class A&B), UL 1699B and other certifications, and can be sold in the US and North American markets.

▲How to connect single-phase inverter to Guam three-phase 240V power grid

Guam's three-phase power grid has two voltages: 240V and 480V. Small-scale industrial and commercial enterprises generally use a three-phase 240V power grid structure, which can be combined with a single-phase inverter, as shown in the figure above; medium and large-scale industrial and commercial enterprises generally use a three-phase 480V power grid structure, which can be matched with the Growatt 10-40KTL3-US model, as shown in the figure below.

▲How to connect the three-phase inverter to the US three-phase 480V grid

In October 2019, three rooftops of shopping malls in Guam, including two 100kW three-phase 240V projects and one 200kW three-phase 480kW project, were successfully connected to the grid. Growatt provided technical solutions and inverters, which have been accepted by the Guam Power Authority (GPA).

Guam has very good lighting resources. After being connected to the grid, a 100kW power station can generate more than 500 kWh of electricity per day. It is estimated that the annual power generation of 100kW can reach 140,000 kWh. Calculated at a cost of RMB 7 per watt, 100kW requires an investment of RMB 700,000. Guam has no photovoltaic subsidy policy, but the electricity price is high. The self-use electricity fee is equivalent to RMB 1.75 per kWh. If the electricity is not used up during the day, the photovoltaic electricity sent to the grid can also be offset against the user's grid electricity consumption. The annual electricity bill income of 140,000 kWh is about RMB 250,000, so the cost can be recovered in less than 3 years.

▲Growatt Guam Project

Although Guam has good sunlight resources and high electricity rates, the Guam Power Authority (GPA) has very high requirements for projects, and local material and labor costs are also high. Almost all equipment and materials for photovoltaic systems (including photovoltaic modules, inverters, cables, distribution cabinets, brackets, cable trays, etc.) are shipped in from outside the island and all require UL certification, which places high demands on construction.