# US 10,312,857 B2 · Systems and methods for an enhanced watchdog in solar module installations

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- Number: US 10,312,857 B2
- Document ID: US10312857B2
- Status: Granted
- Kind: B2
- Application number: 14/572,458
- Filed: 2014-12-16
- Published: 2015-04-16
- Granted: 2019-06-04
- Earliest claimed: 2009-09-03
- Assignees: Tigo Energy, Inc.
- Applicants: Tigo Energy, Inc.
- Inventors: Ron Hadar; Shmuel Arditi
- Web page: https://patentgrep.com/patent/US10312857B2

## CPC

- H02S 50/10: Testing of PV devices, e.g. of PV modules or single PV cells (testing of semiconductor devices during manufacturing {H10P74/00})
- H02S 40/32: comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
- H02S 40/34: comprising specially adapted electrical connection means to be structurally associated with the PV module, e.g. junction boxes
- H10F 77/63: Arrangements for cooling directly associated or integrated with photovoltaic cells, e.g. heat sinks directly associated with the photovoltaic cells or integrated Peltier elements for active cooling
- H10F 77/955: {for photovoltaic devices}
- H02S 50/00: Monitoring or testing of PV systems, e.g. load balancing or fault identification
- H02S 50/15: using optical means, e.g. using electroluminescence
- Y02E 10/50: Photovoltaic [PV] energy
- H02S: GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES (obtaining electrical energy from radioactive sources G21H1/12; light sensitive inorganic semiconductor devices H10F; light sensitive organic semiconductor devices H10K30/00; thermoelectric devices H10N10/00; pyroelectric devices H10N15/00)
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Systems and methods for automatically or remotely rendering a solar array safe during an emergency or maintenance. A watchdog unit is disclosed for monitoring a signal from a central controller. If the signal is lost, interrupted, or becomes irregular, or if a shutdown signal is received, then the watchdog unit can shut down one or more solar modules. Shutting down a solar module can mean disconnecting it from a power bus of the solar array or lowering the solar module voltage to a safe level.

## Claims

### Claim 1

A photovoltaic system, comprising:
a power bus;
a central controller;
an inverter coupled between the power bus and a power grid; and
a plurality of photovoltaic modules, each respective photovoltaic module of the photovoltaic modules having a watchdog unit coupled between the respective photovoltaic module and the power bus, the watchdog unit comprising:
a converter configured to convert power generated by the respective photovoltaic module for the power bus;
a communication connection to the central controller;
a local controller; and
at least one switch coupled between photovoltaic cells of the respective photovoltaic module and the power bus;
wherein the local controller is configured via hardware, or software, or combination of hardware and software to:
receive, over the communication connection, a communication from the central controller;
determine whether the communication connection containing a shutdown command;
control the at least one switch to disconnect the converter from the power bus, in response to the communication containing a shutdown command;
determine whether the communication from the central controller has been interrupted for a time period longer than a predetermined number of allowed skips, when the communication contains no shutdown command;
control the at least one switch to connect the converter to the power bus, in absence of a determination by the local controller that the communication from the central controller has been interrupted for a time period longer than the predetermined number of allowed skips; and
control the converter to lower an output of the converter to the power bus to below a predetermine threshold in response to a determination by the local controller that the communication from the central controller has been interrupted for a time period longer than the predetermined number of allowed skips.

### Claim 2 (depends on 1)

The photovoltaic system of claim 1, wherein the communication from the central controller is via a wired connection.

### Claim 3 (depends on 1)

The photovoltaic system of claim 1, wherein the communication from the central controller is via a wireless connection.

### Claim 4 (depends on 1)

The photovoltaic system of claim 1, wherein the local controller controls a duty cycle of the at least one switch to control an output voltage of the respective photovoltaic module.

### Claim 5 (depends on 2)

The photovoltaic system of claim 2, wherein the local controller is powered by the respective photovoltaic module.