Installation Guide

Planning
900-0168-01-00 Rev C 13
EXAMPLE #2
A. Backup loads: 720 W)
B. Hours of use: 3
C. Days of autonomy: 2
D. Off-grid system (VFXR3024E inverter)
E. Conductor efficiency: 97% (0.97)
F. Inverter efficiency: 92% (0.9)
G. System voltage: 24 Vdc
H. Batteries: OutBack EnergyCell 200RE (12 Vdc)
I. Capacity at 8-hour rate: 167.5 Ahr
J. Maximum DoD: 50% (0.5)
Generator

FXR inverters can accept power from a single-phase generator that delivers clean AC power in the range of
voltage and frequency specified for that model.
~ Inverters stacked for three-phase output can work with three-phase generators.

The inverter/charger can provide a start signal to control an automatic start generator. If automatic generator
starting is required, the generator must be an electric-start model with automatic choke. It should have
two-wire start capability. For other configurations, additional equipment may be required.

In any configuration, the inverter may need to be specifically programmed using the system display.
Perform all programming according to the specifications of the generator and the required operation of the
inverter. Parameters to be program med may include generator size, automatic starting requirements, and
potential fluctuations in generator AC voltage.

A generator that is to be installed in a building usually should
not
have a bond between the neutral and
ground connections. The generator should only be bonded if there is a specific need. Local or national
codes may require the neutral and ground to be bonded at the main electrical panel. See page 18 for more
information on neutral-ground bonding.
Generator Sizing
A generator should be sized to provide enough power for all the loads and the battery charger. The
generator size should assume maximum loads and maximum charging at the same time.

Available generator power may be limited by ratings for circuit breakers and/or generator connectors.

The generator must be able to provide current to all inverters on a given phase or output. Minimum
generator size
2
is recommended to be twice the power of the inverter system. For example, a 2 kVA inverter
should have a 4 kVA generator. Many generators may not be able to maintain AC voltage or frequency for
long periods of time if they are loaded more than 80% of rated capacity.
2 This is the generator size after derating for environment, use, and other factors.
1) A ÷ [E x F] 720 ÷ (0.97 x 0.9) = 801.8 W
2) 1 ÷ G 824.7 ÷ 24 = 34.4 Adc
3) 2 x B 34.4 x 3 = 103.1 Ahr
4) [3 x C] ÷ J [103.1 x 2] ÷ 0.5 = 412.4 Ahr
5) 4 ÷ I 412.4 ÷ 167.5 = 2.5 (rounded to 3)
6) [G ÷ H] x 5 [24 ÷ 12] x 3 strings = 6 batteries