Growatt Off-Grid Inverters for 120V and 120/240V Systems

The SPF 12000T DVM-US MPV is a low-frequency inverter with a built-in pure-copper transformer. It weighs about 165 lb (75 kg) and has a 36kW surge rating, making it well suited to hard-starting loads such as well pumps, large air conditioners and shop tools. The SPE 12000 US is a lighter, more compact high-frequency inverter that accepts PV input up to 550VDC and supports parallel expansion.

Choose the SPF when heavy motor starting loads are the priority and a single 12kW inverter is sufficient. Choose the SPE when you want higher PV string voltage, lower inverter weight or the ability to add parallel inverters later.

Every off-grid inverter consumes power while it remains on. Low-frequency units such as the SPF 12000T generally draw more at idle than high-frequency SPE models because the large transformer stays energized. Over a long winter night, this self-consumption can use a meaningful share of the battery bank.

Include inverter self-consumption when sizing storage and confirm the exact value in the datasheet for your model. If AC power is not needed overnight, a supported schedule or power-saving mode may reduce the loss.

The models use different PV-voltage architectures, so a string designed for one should not be copied to the other.

Panel open-circuit voltage rises in cold weather. Calculate string voltage at the lowest expected site temperature, not only at 77°F (25°C). Exceeding the inverter's maximum PV voltage can cause an over-voltage fault and equipment damage. Send us the panel model and project location if you need help checking a proposed string.

The SPE series can supply loads directly from solar without a connected battery. Without a battery to buffer sudden load changes or passing clouds, output can dip or shut down, so batteryless operation is better suited to light, non-critical loads. Parallel SPE operation requires batteries. For whole-home or critical-load systems, install and commission the battery bank before normal operation.

Supported Growatt off-grid inverters use RS485 or CAN closed-loop BMS communication with Growatt ALP LV batteries and compatible third-party batteries.

1. Confirm that the exact battery and inverter models use a supported protocol.
2. Use the required communication cable and pinout.
3. Select the matching battery type and protocol in the inverter settings.

If communication fails, the inverter may fall back to voltage-based control. State-of-charge readings can then become inaccurate or unstable. Follow the battery manufacturer's Growatt integration guide for the required protocol, firmware and cable pinout.

This is usually caused by settings rather than a hardware fault. Output-source priority interacts with battery voltage or state-of-charge thresholds that determine when the inverter transfers to the AC source and when it returns to battery power. Thresholds that are too close together, or that do not match the battery's voltage curve, can cause early transfers or repeated switching.

Review the switch-to-grid and return-to-battery values in the manual. With lithium batteries, use supported closed-loop communication so decisions are based on BMS-reported state of charge rather than voltage alone.

Both the SPF 12000T DVM and SPE 12000 US provide 120/240V split-phase output: 120V from either leg to neutral and 240V across both legs. Each 120V leg can carry only about half of the inverter's total rated output. A large 120V appliance can therefore overload one leg even when total household demand remains below 12kW.

Balance 120V branch circuits across both legs and connect the largest suitable loads at 240V. Final panel wiring, neutral handling and overcurrent protection should be completed by a qualified electrician.

The SPE 12000 supports up to nine units in parallel for up to 108kW of inverter output. Use identical models with the same firmware, install the specified parallel communication and current-sharing cables, and assign each inverter's role and phase correctly.

The SPF 12000T DVM is designed as a standalone inverter and does not support parallel operation. If future expansion beyond 12kW is likely, start with the SPE platform.

The inverter checks incoming AC voltage, frequency and waveform quality before connecting. Open-frame portable generators may drift in frequency or produce distorted power, especially at light load, causing the inverter to reject the source.

• Use an inverter generator with clean sine-wave output.
• Size the generator so it does not operate continuously near its limit.
• Where supported, use the wider APL or appliance input range instead of UPS mode.

The SPF 12000T input range is 184-272VAC in UPS mode and 154-272VAC in APL mode. Confirm settings in the current manual before commissioning.

A common cause is a neutral-to-ground bond in more than one location. Off-grid inverters may manage bonding differently when passing through grid or generator power versus operating from the battery. A second fixed bond in a downstream panel can place normal return current on the equipment-grounding path, causing nuisance GFCI trips and a potential shock hazard.

The system must maintain the correct single neutral-to-ground bonding point in every operating mode. Have a licensed electrician verify grounding, bonding and transfer behavior against the inverter manual and applicable electrical code.

Some fan noise and warmth are normal, particularly with transformer-based SPF models. Install the inverter in a cool, well-ventilated location, maintain the clearances stated in the manual, and avoid enclosed closets or excessively hot garages.

Do not replace internal fans with lower-airflow aftermarket fans because this can cause over-temperature shutdowns and may affect warranty coverage. If temperature alarms continue with proper ventilation, contact us for diagnosis.

Growatt's cloud platform supports basic remote monitoring, but updates are not always real-time and internet connections can drop. Some DIY system owners add local third-party monitoring such as SolarAssistant, connected by USB or RS485 to a small computer. This can provide faster local data, historical logging and Home Assistant integration.

Third-party monitoring is not supported by Growatt. Use it cautiously, especially for remote setting changes, and retain the Growatt monitoring path needed for manufacturer support.