All USA households use 120 AND 240Vac SIMULTANEOUSLY, aka Split Phase (SP). If you buy non-SP, your inverter can only supply 120Vac OR 240Vac but not both simultaneously, that this inverter can. If you have many/high inductive loads like aircon, fridge, water pumps, and motors that demand high starting peak power then you want industrial-grade low-frequency and not high-frequency inverters. This inverter is industrial-grade, using torrondial transformer. Non-industrial grade inverters will fail after a few years if used with inductive loads.

The ST3000W-OGSP is an off-grid industrial-grade inverter that is powered by any one of, or a combination of 3 power sources: the utility grid (or generator), battery, and solar energy, hence termed hybrid inverter. It is a split-phase inverter, a common wiring standard in USA households.. The inverter output has 120Vac (tapped from L1 + N or L2 + N) and 240Vac (L1 + L2), and a 120Vac universal socket. Low-frequency inverters, like this ST3000W-OGSP, are more robust, have longer lifespan than high-frequency inverters, especially so when used with inductive loads (e.g., well pumps, fridge, motors, aircon). The battery for ST3000W-OGSP must be 48Vdc. Its peak power is 9000W.

Advantages over competitors:

Features

Modes of Operation

All 3 modes can have grid, solar, and battery connected simultaneously. But each mode varies in behavior. This inverter can run with solar alone (see solar fluctuations/limitations below).

1. Utility/Mains/Generator Priority - aka UPS (uninterrupted power supply), if grid fails battery kicks in automatically
   This is the default and recommended mode. Utility wiring is connected to the inverter's AC INPUT terminals (L-L = 240Vac only) and the utility is used to charge the battery and power the load, i.e., household appliances. If the utility fails (or not available), e.g., in a power blackout, the battery kicks in (within 8ms) to power the inverter, which convert battery's DC voltage to inverter's output in AC OUTPUT terminals (split phase = 120Vac [N + L1 or N + L] and 240Vac [L1 + L2]). Mode#1 sees a 55.2V at the battery terminal, which is within charging voltage range for 48V Lead Acid, Gel, or AGM. So, for lithium, you need to lower the charging voltage (see User Manual for how).
   
   
2. Energy Saving Mode (detect any load every 10 seconds, no load = go to sleep for 10 seconds)
   This is same as Mode#1 but the battery operation is set to energy saving mode. In energy saving mode, the inverter goes into sleep mode and wakes every 10 seconds to check what is the load demand. If the load demand is less than 10% of the inverter's rated power (10% of 3000W = 300W), the inverter will not supply power to the load. For example, if your load totaled 200W (e.g., a lamp and radio), inverter will not awake to power it. If your load is a water heater (e.g., 2000W), when the inverter awakes at the 10 seconds cycle it will stay awake to power the water heater. Powering an offgrid shed that has frequent long offs duration of its loads, is a likely working scenario suitable for Mode2.
   
   
3. Inverter/Solar Priority
   This is similar to mode#1 but grid is not use (thus saving on electricity bill) to charge the battery, solar panels charge the batteries. If grid is connected but solar not connected, battery terminal at inverter is 35V, so won't charge a 48V battery, as designed. If battery and solar are at least 90%, solar directly power loads (hence improving battery lifespan), and connected grid is for backup if solar/battery become deficient (i.e., solar below 70Vdc or battery dips to set low-voltage threshold).
   

In a site where there is no utility power, mode#1 is what you would most likely use. Mode#2 is useful if the whole household load has frequent long offs duration, for example. This is an unlikely situation, so pure off-grid sites would likely be using mode#1. Mode#1 is useful for a site with grid but has frequent power blackouts, so the power source automatically transitions to battery power on blackouts.

Operational Notes

When powered by solar alone, solar voltage must be 70-180Vdc (both PV and Battery switches must be in the On-position). With solar-only input, battery terminal measures about 48Vdc, which can charge your 48Vac battery. However, solar voltage fluctuates with the weather and if during operation the solar voltage dips below the minimum, connected appliances might be shut down. Therefore a solar voltage of about 100V might give a safer margin from weather fluctuations and give an above 48V at battery terminal to charge 48V battery. Appliances like lights might be alright with random on/off but desktop computer will not be and should never be connected when any inverter brand is on solar only.

For offgrid inverters with other wattages, please take a look at our 6000W