Installation Guide

Planning
900-0144-01-01 Rev B 9
EXAMPLE #2
A. Backup loads: 1.75 kW (1750 W)
B. Hours of use: 8
C. Days of autonomy: 2
D. Off-grid system (GS3548E inverter)
E. Conductor efficiency: 97% (0.97)
F. Inverter efficiency: 92% (0.92)
G. System voltage: 48 Vdc
H. Batteries: OutBack EnergyCell 200RE (12 Vdc)
I. Capacity at 8-hour rate: 167.5 Ahr
J. Maximum DoD: 50% (0.5)
Generator
These Radian models can work with any single-phase generator that delivers reliable AC power at the
appropriate voltage and frequency. These models can work with three-phase generators when
stacked for three-phase output.

The Radian 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 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 programmed may include generator size, automatic starting requirements, and potential
fluctuations in generator AC voltage.
Generator Sizing
A generator should be sized to provide enough power for all the loads and the battery charger.

Available generator power may be limited by ratings for circuit breakers and/or generator connectors.
The maximum allowed AC circuit breaker size is 50 Aac per Radian inverter/charger.

The generator must be able to provide current to all inverters. Minimum generator wattage
1
is usually
recommended to be twice the wattage of the inverter system. 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.

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
electric codes may require the neutral and ground to be bonded at the main electrical panel. See page 22
for more information on neutral-ground bonding.
1
This is the wattage value after deratings for the following: peak versus continuous power, load power factor considerations,
fuel type, altitude, and ambient temperature.
1) A ÷ [E x F] 1750 ÷ (0.97 x 0.92) = 1961.0 W
2) 1 ÷ G 1961.0 ÷ 48 = 40.9 Adc
3) 2 x B 40.9 x 8 = 326.8 Ahr
4) [3 x C] ÷ J [326.8 x 2] ÷ 0.5 = 1307.3 Ahr
5) 4 ÷ I 1307.3 ÷ 167.5 = 7.8 (rounded to 8)
6) [G ÷ H] x 5 [48 ÷ 12] x 8 strings = 32 batteries