Outback Power Systems GFX1448E, GFX1424E, GFX1312E manual Selling

Operation

Selling

IMPORTANT:

Selling power to the utility company requires the authorization of the local electric jurisdiction. How the local utility company handles this will depend on their policies on this issue. Some may pay for power sold; others may issue credit. Some policies may prohibit the use of this mode. Please check with the utility company and obtain their permission before using this mode.

The GFX inverters are grid-interactive. This means that in addition to using power from the utility grid for charging and loads, these models can also convert excess battery power and sell it to the utility grid. This is known as the “grid-tie” or “Sell” feature. Excess battery power usually comes from renewable energy sources, such as PV arrays, hydroelectric turbines, and wind turbines.

¾The operation of the Sell feature is referenced heavily in the Battery Charging section, as it is integrally tied with the battery charger. In fact, selling is occasionally referred to as “charging in reverse”. Where the charger draws power from the AC input and puts it into the batteries, the Sell feature removes power from the batteries (or the DC system) and returns it to the AC input.

¾The Sell feature can only operate while the utility grid power is stable and within certain limits. If the AC voltage or frequency vary outside these limits, the inverter will stop selling. It may not disconnect from the utility grid. If the inverter stops selling, the system display will show the reason (page 40 has a list of reasons).

¾The inverter’s grid-interactive limits are specified on page 46. The AC source acceptance limits are specified on page 15. These numbers are often not the same.

¾Once the AC voltage and frequency become acceptable, the inverter has a minimum one-minute delay before selling will begin. Upon initial connection to the utility grid, the inverter may be required to perform a full battery charge. This may delay the operation of the sell feature.

¾In the MATE system display, the key set point is sell re volts. In the MATE3, it is Sell Voltage. (See the system display manual to change this set point.) When the charger enters the Sell stage (see pages 18 and 19), it uses sell re volts or Sell Voltage as a reference point. When a renewable source of energy raises the voltage above this point, the inverter exports power to bring the voltage back down or prevent it from rising further. The Sell feature only functions when excess DC (renewable) power is available.

∼The inverter cannot import AC power to raise the voltage to the sell re volts or Sell Voltage set point.

∼The Sell feature can use other set points than sell re volts or Sell Voltage. If the charger is in a different stage, such as Absorption or Float, it uses the Absorption or Float voltage as reference points. As long as the renewable energy exceeds the voltage for that stage, it sells exactly the same as noted above.

¾When power is returned to the utility grid, it is possible to completely reverse the utility meter. The net result would be to sell power to the utility company. However, this depends on whether there are other loads in the system. Loads on the main panel (not on the inverter’s output) may consume this power as fast as it is generated, preventing the meter from running backwards. In this case, the result of selling would be to reduce the consumption of AC power, not reverse it.

¾The maximum amount of power an inverter can sell is not equal to its specified output wattage. It can exceed the specified wattage under some conditions, usually temporarily. (Its maximum output is 30 amps.)

∼However, output will vary with inverter temperature, battery type, and other conditions. The inverter should not be expected to sell 100% of its specified output wattage continuously. Even though it may be able to do so, this may leave it too hot to perform other functions (such as starting heavy loads if they are needed during a utility outage).

∼A good guideline is that the renewable source should be sized to continuously deliver no more than 85% of the inverter’s specified wattage (per inverter, in a multi-inverter system). This recommendation is specifically for the inverter’s Sell feature. In some cases, the source may be sized larger to account for environmental conditions or the presence of DC loads. This depends on individual site requirements.

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