All AC power and voltage registers return zero. What is wrong?

The REFUstore88k may not be in grid-connected operating state. Check the st register (40108) for the current SunSpec state code and the st_vnd register (40109) for vendor detail. If the inverter is in standby or fault, AC measurements will read zero. Resolve any active faults shown in evt_vnd_1 through evt_vnd_4 first.

Scaled readings look like unreasonable large integers. What should I do?

All measurement registers in SunSpec model 103 use paired scale-factor registers (a_sf, v_sf, w_sf, hz_sf, va_sf, va_r_sf, wh_sf, dca_sf, dcv_sf, dcw_sf, tmp_sf). Apply the corresponding signed scale factor as a power of 10 to the raw value. Ignoring scale factors produces readings that are orders of magnitude off.

The Gateway connects but register reads time out intermittently.

The REFUstore88k Modbus TCP server accepts one client connection at a time. If the REFUcontrol BC-10 EMS or another client is polling simultaneously, the Gateway will experience timeouts. Ensure only one Modbus TCP client polls the inverter at a time, or increase the polling interval to reduce contention.

Is it safe to write to the power control and battery current registers?

Write registers such as conn (40186), w_max_lim_pct (40187), pcs_set_operation (40231), max_bat_a_cha (40232), and max_bat_a_discha (40233) directly affect inverter operation and battery current limits. Incorrect values can disconnect the AC output, exceed battery protection limits, or trigger protective shutdowns. Always verify scale factors, confirm the intended value in a test environment, and consult the REFUstore88k documentation before writing to these registers in a live installation.

Free Modbus template: Refu REFUstore88k

Name: Refu REFUstore88k
Brand: Refu
SKU: 153e716b-3fd2-45a0-a223-27bc0809fd39

The Refu REFUstore88k is an 88 kVA bidirectional battery inverter designed for commercial energy storage applications, including self-consumption optimisation and peak shaving. Via Modbus TCP, this template reads the full SunSpec model 103 three-phase AC stack (active power, apparent power, reactive power, per-phase voltages and currents, grid frequency, DC voltage, DC current, DC power), cabinet and heat-sink temperatures, inverter state, and vendor event flags. Write registers let you control the AC connection, cap active power output, adjust power factor, set reactive power, switch local or remote mode, command PCS operating state, and constrain battery charge and discharge current. Connecting the REFUstore88k to your ModbusCloud Gateway gives you full operational visibility and closed-loop control from a single dashboard.

Registers (116)

84 read / 32 write

Name	Address	Function	Type	Unit	Access
id_1 SunSpec model identifier for the Common block.	40002	FC03	uint16		R
l_1 Length of the SunSpec Common block in registers.	40003	FC03	uint16		R
mn Manufacturer name string reported by the device.	40004	FC03	string		R
md Device model name string reported by the device.	40020	FC03	string		R
opt Optional firmware or hardware options string.	40036	FC03	string		R
vr Firmware version string of the device.	40044	FC03	string		R
sn Device serial number string.	40052	FC03	string		R
da Modbus unit address assigned to this device.	40068	FC03	uint16		R
pad_1 Padding register to align the Common block boundary.	40069	FC03	uint16		R
id_103 SunSpec model identifier for the three-phase inverter block.	40070	FC03	uint16		R
l_103 Length of the SunSpec model 103 block in registers.	40071	FC03	uint16		R
a Total AC output current, all phases combined.	40072	FC03	uint16	A	R
aph_a AC output current on phase A.	40073	FC03	uint16	A	R
aph_b AC output current on phase B.	40074	FC03	uint16	A	R
aph_c AC output current on phase C.	40075	FC03	uint16	A	R
a_sf Scale factor applied to all current readings.	40076	FC03	uint16		R
pp_vph_ab Phase-to-phase voltage between phases A and B.	40077	FC03	uint16	V	R
pp_vph_bc Phase-to-phase voltage between phases B and C.	40078	FC03	uint16	V	R
pp_vph_ca Phase-to-phase voltage between phases C and A.	40079	FC03	uint16	V	R
ph_vph_a Phase-to-neutral voltage on phase A.	40080	FC03	uint16	V	R
ph_vph_b Phase-to-neutral voltage on phase B.	40081	FC03	uint16	V	R
ph_vph_c Phase-to-neutral voltage on phase C.	40082	FC03	uint16	V	R
v_sf Scale factor applied to all voltage readings.	40083	FC03	uint16		R
active_power Total AC active power output, watts, signed.	40084	FC03	int16	W	R
w_sf Scale factor applied to active power reading.	40085	FC03	int16		R
hz AC grid frequency, signed raw value.	40086	FC03	int16	Hz	R
hz_sf Scale factor applied to frequency reading.	40087	FC03	int16		R
apparent_power Total AC apparent power, volt-amperes, signed.	40088	FC03	int16	VA	R
va_sf Scale factor applied to apparent power reading.	40089	FC03	int16		R
reactive_power Total AC reactive power, var, signed.	40090	FC03	int16	var	R
va_r_sf Scale factor applied to reactive power reading.	40091	FC03	int16		R
wh Cumulative AC energy throughput, raw watt-hour count.	40094	FC03	uint32	Wh	R
wh_sf Scale factor applied to cumulative energy reading.	40096	FC03	uint16		R
dca DC battery current, signed raw value.	40097	FC03	int16	A	R
dca_sf Scale factor applied to DC current reading.	40098	FC03	uint16		R
dcv DC battery bus voltage, raw value.	40099	FC03	uint16	V	R
dcv_sf Scale factor applied to DC voltage reading.	40100	FC03	uint16		R
dcw DC battery power, signed raw value.	40101	FC03	int16	W	R
dcw_sf Scale factor applied to DC power reading.	40102	FC03	int16		R
tmp_cab Cabinet internal temperature, signed raw value.	40103	FC03	int16	°C	R
tmp_snk Heat-sink temperature, signed raw value.	40104	FC03	int16	°C	R
tmp_sf Scale factor applied to temperature readings.	40107	FC03	uint16		R
st Inverter operating state code per SunSpec definition.	40108	FC03	uint16		R
st_vnd Vendor-specific inverter state code.	40109	FC03	uint16		R
evt_2 SunSpec event flags register 2, bitmask.	40112	FC03	uint32		R
evt_vnd_1 Vendor-specific event flags, word 1, bitmask.	40114	FC03	uint32		R
evt_vnd_2 Vendor-specific event flags, word 2, bitmask.	40116	FC03	uint32		R
evt_vnd_3 Vendor-specific event flags, word 3, bitmask.	40118	FC03	uint32		R
evt_vnd_4 Vendor-specific event flags, word 4, bitmask.	40120	FC03	uint32		R
id_120 SunSpec model identifier for the Nameplate block (120).	40122	FC03	uint16		R
l_120 Length of the SunSpec Nameplate block in registers.	40123	FC03	uint16		R
der_typ DER type code identifying the inverter category.	40124	FC03	uint16		R
w_rtg Rated continuous AC power output, raw value.	40125	FC03	uint16	W	R
w_rtg_sf Scale factor applied to rated power reading.	40126	FC03	uint16		R
va_rtg_sf Scale factor applied to rated apparent power reading.	40128	FC03	uint16		R
var_rtg_q1 Rated reactive power capability in quadrant 1.	40129	FC03	int16	var	R
var_rtg_q2 Rated reactive power capability in quadrant 2.	40130	FC03	int16	var	R
var_rtg_q3 Rated reactive power capability in quadrant 3.	40131	FC03	int16	var	R
var_rtg_q4 Rated reactive power capability in quadrant 4.	40132	FC03	int16	var	R
var_rtg_sf Scale factor applied to rated reactive power readings.	40133	FC03	int16		R
a_rtg Rated maximum AC current output, raw value.	40134	FC03	uint16	A	R
a_rtg_sf Scale factor applied to rated current reading.	40135	FC03	int16		R
pf_rtg_q1 Rated power factor in quadrant 1.	40136	FC03	int16		R
pf_rtg_q2 Rated power factor in quadrant 2.	40137	FC03	int16		R
pf_rtg_q3 Rated power factor in quadrant 3.	40138	FC03	int16		R
pf_rtg_q4 Rated power factor in quadrant 4.	40139	FC03	int16		R
pf_rtg_sf Scale factor applied to rated power factor readings.	40140	FC03	int16		R
pad_120 Padding register to align the Nameplate block boundary.	40149	FC03	int16		R
id_121 SunSpec model identifier for the Basic Settings block (121).	40150	FC03	uint16		R
l_121 Length of the SunSpec Basic Settings block in registers.	40151	FC03	uint16		R
w_max_sf Scale factor applied to maximum power setting.	40172	FC03	uint16		R
v_ref_sf Scale factor applied to voltage reference setting.	40173	FC03	uint16		R
v_ref_ofs_sf Scale factor applied to voltage reference offset setting.	40174	FC03	uint16		R
w_max Maximum AC power output setpoint, write to limit power.	40152	FC16	uint16	W	W
v_ref Voltage reference setpoint for grid voltage regulation.	40153	FC16	uint16	V	W
v_ref_ofs Voltage reference offset setpoint, adjusts nominal voltage.	40154	FC16	uint16	V	W
id_123 SunSpec model identifier for the Immediate Controls block (123).	40182	FC03	uint16		R
l_123 Length of the SunSpec Immediate Controls block in registers.	40183	FC03	uint16		R
w_max_lim_pct_sf Scale factor applied to active power limit percentage.	40205	FC03	uint16		R
out_pf_set_sf Scale factor applied to output power factor setpoint.	40206	FC03	uint16		R
var_pct_sf Scale factor applied to reactive power percentage setpoint.	40207	FC03	uint16		R
conn Connect or disconnect the inverter AC output, write to control.	40186	FC16	uint16		W
w_max_lim_pct Active power output limit as percentage of rated power.	40187	FC16	int16	%	W
w_max_lim_ena Enable flag to activate the active power limit setpoint.	40191	FC16	uint16		W
out_pf_set Output power factor setpoint, write to control power factor.	40192	FC16	int16		W
out_pf_set_ena Enable flag to activate the power factor setpoint.	40196	FC16	uint16		W
var_w_max_pct Reactive power setpoint as percentage of rated power.	40197	FC16	int16	%	W
var_pct_ena Enable flag to activate the reactive power percentage setpoint.	40204	FC16	uint16		W
id_64040 SunSpec model identifier for vendor block 64040.	40208	FC03	uint16		R
l_64040 Length of vendor block 64040 in registers.	40209	FC03	uint16		R
read_write_param_id Parameter ID for the vendor read/write parameter interface.	40210	FC16	uint32		W
read_write_param_index Index for the vendor read/write parameter interface.	40212	FC16	uint32		W
id_64041 SunSpec model identifier for vendor block 64041.	40213	FC03	uint16		R
l_64041 Length of vendor block 64041 in registers.	40214	FC03	uint16		R
read_write_param_value_u32 Parameter value slot, unsigned 32-bit, for vendor interface.	40215	FC16	uint32		W
read_write_param_value_s32 Parameter value slot, signed 32-bit, for vendor interface.	40217	FC16	int32		W
read_write_param_value_f32 Parameter value slot, 32-bit float encoded, for vendor interface.	40219	FC16	int32		W
read_write_param_value_u16 Parameter value slot, unsigned 16-bit, for vendor interface.	40221	FC16	uint16		W
read_write_param_value_s16 Parameter value slot, signed 16-bit, for vendor interface.	40222	FC16	int16		W
read_write_param_value_u8 Parameter value slot, unsigned 8-bit stored as uint16.	40223	FC16	uint16		W
read_write_param_value_s8 Parameter value slot, signed 8-bit stored as int16.	40224	FC16	int16		W
id_64800 Model identifier for the Refu vendor control block 64800.	40225	FC16	uint16		W
l_64800 Length of Refu vendor control block 64800 in registers.	40226	FC16	uint16		W
loc_rem_ctl Local or remote control mode selector, write to switch modes.	40227	FC16	int16		W
pcs_hb Power conversion system heartbeat counter, read to verify comms.	40228	FC03	int16		R
controller_hb EMS controller heartbeat counter, read to verify controller comms.	40229	FC03	int16		R
pcs_set_operation PCS operation mode setpoint, write to command operating state.	40231	FC16	int16		W
max_bat_a_cha Maximum battery charge current limit setpoint.	40232	FC16	uint16	A	W
max_bat_a_discha Maximum battery discharge current limit setpoint.	40233	FC16	uint16	A	W
max_a Maximum AC current limit setpoint.	40234	FC16	uint16	A	W
max_a_cur Maximum AC current curtailment setpoint.	40235	FC16	uint16	A	W
max_bat_a_sf Scale factor applied to battery current limit setpoints.	40236	FC16	int16		W
max_a_sf Scale factor applied to maximum AC current setpoint.	40237	FC16	int16		W
max_a_cur_sf Scale factor applied to AC current curtailment setpoint.	40238	FC16	int16		W
padding_1 Padding register, no operational value.	40239	FC16	int16		W
padding_2 Padding register, no operational value.	40240	FC16	int16		W