All voltage and power values look wrong or too small. Why?

SunSpec Model 64111 uses signed scale-factor registers (v_sf, a_sf, p_sf, ah_sf, kwh_sf). Raw register values must be multiplied by 10 raised to the power of the corresponding scale factor. If your client ignores these registers, all measurements will be off by a fixed power of ten. Ensure your integration reads and applies each scale factor before displaying values.

The gateway connects but all registers return zero or NaN. What now?

Verify the Modbus unit ID configured in the portal matches the device or gateway unit ID exactly. SunSpec devices may use a non-default unit ID such as 1 or a vendor-assigned value. Also confirm the controller's Modbus TCP service is running and reachable on port 502 from the Gateway's network segment.

The chargerst register shows a number. How do I interpret it?

The chargerst field is an enumerated state code. Typical values represent charging stages such as off, bulk, absorption, float, or equalize. Consult the specific controller's Modbus documentation for the exact enumeration table, as values vary by manufacturer implementing this vendor-specific model.

Lifetime counters like lifetimekwhout seem stuck at zero. Is something broken?

Lifetime accumulation registers are uint16 and may have rolled over or may only be updated at defined intervals by the controller firmware. Cross-check with the kwh_sf scale factor to ensure the value is not being misread as zero due to scaling. If the controller has been in service for a long time, the uint16 range may also have overflowed.

Free Modbus template: SunSpec Model 64111 — Basic Charge Controller

Name: SunSpec Model 64111 — Basic Charge Controller
Brand: SunSpec
SKU: 287cc6ef-e1c5-4d6f-b6e7-913eff6861aa

SunSpec Model 64111 is a vendor-specific Modbus TCP model defining the Basic Charge Controller data block, used in off-grid and hybrid solar installations where a MPPT charge controller manages power flow between a PV array and a battery bank. The template reads real-time measurements including battery voltage, array voltage, output power, charge current, and charger state, alongside daily totals for kilowatt-hours and amp-hours output. Lifetime peak records for power, battery voltage, and PV open-circuit voltage are also accessible. Each physical measurement is scaled by a corresponding scale-factor register per the SunSpec standard. Connecting this template in ModbusCloud gives installers continuous visibility into charge controller performance without manual polling.

Registers (25)

25 read / 0 write

Name	Address	Function	Type	Unit	Access
id SunSpec model ID, identifies this as model 64111.	0	FC03	uint16		R
l Model block length in registers, excluding id and l.	1	FC03	uint16		R
port Port or device index within the SunSpec map.	2	FC03	uint16		R
v_sf Scale factor applied to all voltage readings.	3	FC03	int16		R
a_sf Scale factor applied to all current readings.	4	FC03	int16		R
p_sf Scale factor applied to all power readings.	5	FC03	int16		R
ah_sf Scale factor applied to ampere-hour accumulations.	6	FC03	int16		R
kwh_sf Scale factor applied to kilowatt-hour accumulations.	7	FC03	int16		R
battv DC battery bank voltage, scaled by v_sf.	8	FC03	uint16	V	R
arrayv PV array input voltage at the charge controller, scaled by v_sf.	9	FC03	uint16	V	R
outputa Charge current delivered to the battery bank, scaled by a_sf.	10	FC03	uint16	A	R
inputa Current drawn from the PV array input, scaled by a_sf.	11	FC03	uint16	A	R
chargerst Enumerated charger operating state, such as bulk or float.	12	FC03	uint16		R
outputw Instantaneous DC power delivered to the battery, scaled by p_sf.	13	FC03	uint16	W	R
todayminbatv Minimum battery voltage recorded since midnight, scaled by v_sf.	14	FC03	uint16	V	R
todaymaxbatv Maximum battery voltage recorded since midnight, scaled by v_sf.	15	FC03	uint16	V	R
vocv Current PV array open-circuit voltage, scaled by v_sf.	16	FC03	uint16	V	R
todaymaxvoc Maximum PV open-circuit voltage recorded since midnight, scaled by v_sf.	17	FC03	uint16	V	R
todaykwhoutput Energy delivered to the battery today in kilowatt-hours, scaled by kwh_sf.	18	FC03	uint16	kWh	R
todayahoutput Amp-hours delivered to the battery today, scaled by ah_sf.	19	FC03	uint16	AH	R
lifetimekwhout Cumulative energy delivered to the battery over device lifetime.	20	FC03	uint16	kWh	R
lifetimeahout Cumulative amp-hours delivered to the battery over device lifetime, in kAH.	21	FC03	uint16	kAH	R
lifetimemaxout Highest output power ever recorded by the charge controller.	22	FC03	uint16	W	R
lifetimemaxbatt Highest battery voltage ever recorded by the charge controller.	23	FC03	uint16	V	R
lifetimemaxvoc Highest PV open-circuit voltage ever recorded by the charge controller.	24	FC03	uint16	V	R