Outback FX-R Series Technical Note on Input Modes

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Application Note

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Using Inverter Input Modes for Smart Grid Management

Some battery based grid connected inverters from OutBack Power have a unique collection of

functions designed to optimize utility power usage for OutBack customers. This application note

will show how to configure the Radian and FXR class inverters for various power conversion

applications including:

 Backup Power for Grid-Connected Systems

 Selling Excess Power to the Utility Grid

 Avoiding Expensive Time-of-Use Surcharges

 Limiting Peak Demand Charges

 Optimizing Self-Consumption

BACKUP POWER FOR GRID CONNECTED SYSTEMS

The first step in sizing a backup power application is to start with the electrical loads. The basic

backup system for most homes would include power for a refrigerator, lighting, and some

receptacles for powering small appliances and entertainment systems. Table 1 shows a

typical load profile and the amount of energy in watt-hours (Wh) required to run them over a

24-hour period.

Table 1

Calculating Average Daily AC and DC load

LOADS QTY x WATTS =

Total

WATTS x

24 Hours

AVG

Wh/Day

CF Lights 6 x 17 = 100 x 16 =

1,600

Refrigerator 1 x 1,000 = 1,000 x 6 =

6,000

Receptacle Load

Circuit 1 x 600 = 600 x 16 =

9,600

AC TOTAL WATTS

1700

AC AVG DAILY

LOAD

17,200 Wh

Summary of content (10 pages)

PAGE 1
Application Note Using Inverter Input Modes for Smart Grid Management Some battery based grid connected inverters from OutBack Power have a unique collection of functions designed to optimize utility power usage for OutBack customers.
PAGE 2
Application Note Using the 17,200 watt hours (17.2 kWh) in Table 1, and a battery depth-of-discharge (DOD) of 80%, we would need a battery bank with a capacity of 21.5 kWh to back up the loads for 24 hours. Quite often a DOD of 50% is used in battery-based off-grid systems since a shallower discharge extends the life of the battery.
PAGE 3
Application Note To size the inverter, we use the total watts column in Table 1. This is the maximum power the inverter would need to deliver to the loads if they were all running at the same time. The ambient temperature affects inverter conversion efficiency at 1% per degree C above 25°C. If the worst-case temperature is 40°C, then the inverter needs to be derated by 15%.
PAGE 4
Application Note and blending it with 10A from the AC grid-side of the inverter to meet the 30A demand from the load panel. Note that some amount of charging current will always be diverted to the batteries before going to the inverter as even a “full” battery draws about 2% of its amp hour rating when a charging voltage is applied. More details on the Offset function can be found in the Offset Functionality application note on the OutBackPower.com website.
PAGE 5
Application Note form of a feed-in tariff program that can vary widely depending on the local state and utility policies. When the grid goes down, the main load panel (to the right of the inverter in Figure 3) will also lose power but the critical loads panel (to the left of the inverter in Figure 3) will continue to power loads from energy stored in the batteries and/or from the PV array.
PAGE 6
Application Note surplus PV power being generated during this time can be stored in the OutBack grid/hybrid inverter’s battery bank for use at a later time. The OutBack MATE3 has up to three grid use timers for weekdays and one grid use timer for the weekend. The Use and Drop settings determine the actual connection times to the grid. The Use period defines the beginning time of the grid connection.
PAGE 7
Application Note Applications for full self-consumption include sites where the local utility does not allow connection agreements with PV based inverters, or where the site owner wants to become mostly off-grid, with the utility providing the occasional make-up power, acting like a backup generator for when the PV array cannot satisfy all of the site’s load demand.
PAGE 8
Application Note cycle life. So for three strings of OutBack 200RE batteries about 1500 W minimum AC load, or 30 Adc is best. 2. Be sure the RE kWh exceeds the load kWh or the batteries may be chronically undercharged as the batteries compete with the loads for power to recharge themselves. The RE kWh minus the load kWh must equal enough charging current during the RE period to properly charge the batteries. 3.
PAGE 9
Application Note Table 1 – Radian/FXR Input Mode Function Matrix Sells To Grid Charges Batteries From Grid Uses PV To Offset Power From Grid Uses PV To Charge Batteries Limits DC Discharge Through Inverter Grid Use Timers Must Have More RE kWH than Load kWh User Settable Low Battery Limit Has Maximum Current Limit From Grid Blends Grid Power With RE During Peaks ©2015 Grid Tied √ √ √ √ Support √ √ √ OutBack Power Technologies, Arlington, WA 98223 √ √ √ √ √ Grid Zero √ √ √ Mini Grid Optional √ √
PAGE 10
Application Note About OutBack Power Technologies OutBack Power Technologies is a leader in advanced energy conversion technology. OutBack products include true sine wave inverter/chargers, maximum power point tracking charge controllers, and system communication components, as well as circuit breakers, batteries, accessories, and assembled systems.