MUST PV1800 register map
Derived from the manufacturer protocol document
PH1800 PV1800 EP1800 PV3500 EP3500 RS485 Modbus RTU communication Protocol 1.4.15.xlsx
shipped in the taHC81/MUST-ESPhome
GitHub repo. Only the registers this monitor reads are listed here;
the full document covers hundreds more.
All values are Modbus RTU holding registers (function code 0x03),
unless otherwise noted. RO = read-only, RW = read/write.
CHARGER block (start at 15201)
| Addr |
RO/RW |
Name |
Unit |
Notes |
| 15201 |
RO |
Charger workstate |
— |
0=Init, 1=Standby, 2=Charging, 3=Fault, 4=Flash |
| 15202 |
RO |
MPPT state |
— |
0=Stop, 1=Start, 2=Normal, 3=MPPT limit, 4=Float |
| 15203 |
RO |
Charging state |
— |
0=Stop, 1=Precharge, 2=CC, 3=CV, 4=Float, 5=Current derating |
| 15204 |
RO |
reserved |
— |
|
| 15205 |
RO |
PV voltage |
0.1 V |
|
| 15206 |
RO |
Battery voltage (charger side) |
0.1 V |
|
| 15207 |
RO |
Charger current |
0.1 A |
|
| 15208 |
RO |
Charger power |
W |
|
When you ask for register 15201 with count=1 the inverter dumps the
entire block (49 registers, addresses 15201..15249). The registers
listed here are 15201..15208.
INVERTER block (start at 25201)
| Addr |
RO/RW |
Name |
Unit |
Notes |
| 25201 |
RO |
Work state |
— |
0=PowerOn, 1=SelfTest, 2=OffGrid, 3=GridTie, 4=ByPass, 5=Stop, 6=GridCharging |
| 25202 |
RO |
AC voltage grade |
V |
230=230V variant, 120=120V variant |
| 25203 |
RO |
Rated power |
VA |
|
| 25204 |
RO |
reserved |
|
|
| 25205 |
RO |
Battery voltage |
0.1 V |
|
| 25206 |
RO |
Inverter voltage |
0.1 V |
|
| 25207 |
RO |
Grid voltage |
0.1 V |
|
| 25208 |
RO |
BUS voltage |
0.1 V |
|
| 25209 |
RO |
Control current |
0.1 A |
|
| 25210 |
RO |
Inverter current |
0.1 A |
|
| 25211 |
RO |
Grid current |
0.1 A |
|
| 25212 |
RO |
Load current |
0.1 A |
|
| 25213 |
RO |
PInverter |
W |
signed in this script; protocol says unsigned 1W |
| 25214 |
RO |
PGrid |
W |
signed (negative = exporting to grid) |
| 25215 |
RO |
PLoad |
W |
signed (negative = ??? on this firmware) |
| 25216 |
RO |
Load percent |
% |
unit is percent (raw integer, NOT ×0.01) |
| 25217 |
RO |
SInverter |
VA |
|
| ... |
|
(more S/Q regs, frequencies, temps, relays, accumulators) |
|
|
| 25233 |
RO |
AC radiator temperature |
°C |
|
| 25234 |
RO |
Transformer temperature |
°C |
|
| 25235 |
RO |
DC radiator temperature |
°C |
often 0 on units without that sensor |
| ... |
|
|
|
|
| 25273 |
RO |
Batt power |
W |
signed |
| 25274 |
RO |
Batt current |
0.1 A |
signed |
| 25275 |
RO |
Batt voltage grade |
V |
12, 24, or 48 |
This monitor polls 25201..25274 (74 registers). The inverter returns
all of them in one response when asked.
SETTINGS blocks (split into two ranges)
10103..10104
| Addr |
RO/RW |
Name |
Unit |
| 10103 |
RW |
Float voltage |
0.1 V |
| 10104 |
RW |
Absorb voltage |
0.1 V |
20118..20132
| Addr |
RO/RW |
Name |
Unit |
| 20118 |
RW |
Battery stop discharging voltage |
0.1 V |
| 20119 |
RW |
Battery stop charging voltage |
0.1 V |
| 20127 |
RW |
Battery low voltage |
0.1 V |
| 20128 |
RW |
Battery high voltage |
0.1 V |
| 20132 |
RW |
Max combine charger current |
0.1 A |
Decoded state values
Charger workstate (15201)
| Value |
Meaning |
| 0 |
Initialization mode |
| 1 |
Standby |
| 2 |
Charging |
| 3 |
Fault |
| 4 |
Flash |
MPPT state (15202)
| Value |
Meaning |
| 0 |
Stop |
| 1 |
Start |
| 2 |
Normal work |
| 3 |
MPPT limit |
| 4 |
Float |
Charging state (15203)
| Value |
Meaning |
| 0 |
Stop |
| 1 |
Precharge |
| 2 |
CC (constant current) |
| 3 |
CV (constant voltage) |
| 4 |
Float |
| 5 |
Current derating |
Inverter workstate (25201)
| Value |
Meaning |
| 0 |
PowerOn |
| 1 |
SelfTest |
| 2 |
OffGrid |
| 3 |
Grid-Tie |
| 4 |
ByPass |
| 5 |
Stop |
| 6 |
GridCharging |
Notes on this unit
- Battery voltage grade is 24 V (24V battery system).
- AC voltage grade is 120 V (120V variant, not the 230V default).
- Confirmed against live readings:
Battery voltage = 28.2 V,
Inverter voltage = 115.7 V, Grid voltage = 117.0 V.
