FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Solar Charge Controller System for Supplying Load and Method Therefor"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & TOUBRO LIMITED,
L&T House, Ballard Estate, P. 0. Box: 278, Mumbai 400 001, India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Solar Charge Controller System for Supplying Load and Method Therefor
Field of the invention
The present invention generally relates to a charge controller for power supply devices including UPS/ inverter applications, and more particularly, to a smart solar charge controller for charging UPS/ inverter batteries in the circuit directly from solar power.
Background of the invention
Photovoltaic panel generates electrical energy by direct conversion of incident sunlight. The resulting electrical energy can be accumulated in a storage battery. However, it is necessary to regulate the electrical charge provided to the storage battery so as to protect against excessive voltage and various problems related thereto.
Nowadays, UPS (Uninterrupted Power Supply) unit has become a necessity for providing a backup for loads in case of power failure. UPS and inverters are essential for most of the computer networks and personal computers also due to power shortages. For UPS or on-line inverters, AC is converted into DC and then DC is converted into required AC. The same principle is followed even when input supply to the UPS/inverter is coming from solar power based system. The solar output is essentially DC output. However, conversion of the DC supply into AC and then into DC and again into AC leads to inefficiency and loss of power.
Energy consumption is increasing day by day, so it is imperative to save as much power as possible to save society from power crises.
Accordingly, there exists a need to provide solar charge controller which addresses the aforesaid issues.
Objects of the invention

An object of the present invention is to provide more efficient utilization of solar power to charge the batteries directly, by avoiding the need of multiple conversions from DC into AC and again into DC.
Another object of the present invention is to detect source of available power for smart utilization of available resources.
Summary of the invention
Accordingly, the present invention provides a solar charge controller system for power '
supply devices including UPS (Un-interrupted Power Supply) units and inverters. The solar charge controller system includes a solar array junction box coupled to a solar photovoltaic system. The solar array junction box is capable of accumulating electrical energy from the solar photovoltaic system. Further, the solar charge controller system includes a charge controller being capable of controlling an electrical input from the solar array junction box to batteries of the UPS unit for charging the batteries. The charge controller includes a sensor unit being capable of sensing availability of sunlight, a battery charge monitoring unit for monitoring voltage of the batteries, a load switching unit capable of connecting/disconnecting the loads to the solar array junction box based on voltage of the batteries, a power path selection unit capable of prioritising and selecting the source of power from any one solar photovoltaic system and grid power for charging the batteries, and a central control unit controlling and monitoring the sensor unit, the battery charge monitoring unit, the load switching unit and the power path selection unit; wherein, the power path selection unit diverts the input of the batteries from the solar array junction box to grid power upon receiving a signal of nonavailability of sunlight from the sensor unit.
Brief description of the drawings
Figure 1 shows a schematic drawing of conventional system for using UPS (uninterrupted power supply) unit supplying power to the load in case of grid power interruptions; and

Figure 2 shows a block diagram of a solar charge controller system, in accordance with the present invention.
Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The present invention provides a solar charge controller system. The solar charge controller system provides better utilization of solar power to charge the batteries directly. Further, the solar charge controller system detects available sources of power and effects smart utilization thereof, by preferential selection. When the sunlight is bright, the solar cells produce more voltage and this excessive voltage may damage the batteries. The charge controller of the present invention is used to maintain the proper charging voltage on the batteries. As the input voltage from the solar array rises, the charge controller regulates the charge to the batteries preventing any overcharging so as to extend the battery life. The function of the charge controller is to disconnect the solar panel when the battery becomes charged and re-connect the solar panel when the battery needs recharging.
Referring to figure 2, there is shown a schematic drawing of the solar charge controller system (100) (hereinafter 'the system (100)') in accordance with the present invention. The system (100) is shown to include a solar photovoltaic system (10), a solar array junction box (20), a charge controller (30), AC to DC converter (40), and UPS (Uninterrupted Power Supply) unit (50).
The solar photovoltaic system (10) includes a plurality of photovoltaic cells (not shown) that convert solar energy directly into electricity by the photovoltaic effect. The electricity generated by the solar photovoltaic system (10) is supplied to the solar array junction box (20). The solar array junction box (20) is capable of collecting and

accumulating electrical energy from the solar photovoltaic system (10) for distributing further to loads (70).
Generally, the solar array junction box (20) provides an electrical contact between solar photovoltaic system (10), the grid (60) and the loads (70). The charge controller (30) senses electrical input from the solar array junction box (10) and charges batteries of the UPS (Un-interrupted Power Supply) unit (50). Since the solar array junction box (20) delivers the energy in terms of direct current (DC), batteries of the UPS unit (50) can be charged directly without voltage/current modulation device.
The charge controller (30) is electrically connected to the solar array junction box (20) which continuously delivers unregulated power. The charge controller (30) is also connected to the batteries of the UPS (Un-interrupted Power Supply) unit (50). The charge controller (30) includes a sensor unit, a battery charge monitoring unit, a load switching unit, a power path selection unit, and a central control unit.
The sensor unit senses availability of sunlight. Further, the battery charge monitoring unit (not shown) continuously monitors voltage of the batteries of the UPS unit (50). The battery charge monitoring unit measures the. battery voltage continuously with the help of a voltage divider circuit and feeds this input to the central control unit. When the battery voltage falls below a "low" set limit, the charge controller (30) disconnects the dump load and allows the battery to charge using the load switching unit. If the voltage rises above a "high" set limit, the charge controller (30) turns on a dump load and isolates the battery from further charging.
Specifically, the load switching unit (not shown) connect/disconnect the loads based on voltage of the batteries. The load switching unit employs control field-effect transistors (FETs) to trigger switching action as and when required. The gates of the control FETs are connected to the output pins of the central control unit. To enhance the current carrying capacity, thyristor based power electronic circuits are used for switching the load.

Furthermore, the power path selection unit (not shown) automatically prioritises and selects the source of power to be used for battery charging. Specifically, the power path selection unit diverts the input of the batteries from the solar array junction box to grid power upon receiving a signal of non-availability of sunlight from the sensor unit. More specifically, the power path selection unit automatically scans availability of the different power sources to start battery charging. The voltage at the output of the different power sources is measured using voltage divider circuits. This measured value is digitized and fed to the central control unit which selects the appropriate power source for battery charging, based on a priority list.
For example, for power sources A, B and C and output voltage from the power sources Va, Vb and Vc respectively, if the priority is assigned in the order A > B > C, then the charge controller (30) first checks Va and compare it with a threshold value Vth, which is the minimum value to enable charging. If Va is greater than Vth , the power source A will be selected for charging the battery. If Va is less than Vth , then source B or C will be selected for charging the battery in the same order after comparing Vb and Vc with Vth respectively.
The central control unit (not shown) controls and monitors the battery charge monitoring unit, the load switching unit and the power path selection unit. Specifically, the battery charge monitoring unit, the load switching unit and the power path selection unit are interfaced with the central control unit. In an embodiment, the central control unit is a microcontroller with analog-to-digital converter. The central control unit continuously monitors operating conditions and adjusts the charger performance based on the system's needs.
As the solar array junction box (20) delivers DC current, the charge controller (30) enables battery charging without any rectification. The charge controller (30) also has protective circuits for reverse polarity protection and inrush current control.
In the present system (100), the charge controller (30) acts as an auto input source for battery charging. The charge controller (30) takes care of overcharging and protects

from complete draining of the batteries of the UPS unit (50). There has been set a reserve level of battery. After reaching the reserve level the smart charge controller allows the grid power to enter UPS to take over load, and solar PV will charge the battery.
Advantages of the invention
1. The solar charge controller system (100) helps to charge the UPS/ inverter batteries in the circuit directly from solar, instead of first converting solar DC into AC and then AC into DC to charge the batteries.
2. The solar charge controller system (100) detects source of available power for smart utilization of available resources.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We claim
1. A solar charge controller system for power supply devices including UPS (Un-interrupted Power Supply) unit and inverter, the solar charge controller system comprising:
a solar array junction box coupled to a solar photovoltaic system, the solar array junction box being capable of accumulating electrical energy from the solar photovoltaic system; and
a charge controller being capable of controlling an electrical input from the solar array junction box to batteries of the UPS unit/inverter for charging the batteries, the charge controller having,
a sensor unit being capable of sensing availability of sunlight,
a battery charge monitoring unit for monitoring voltage of the batteries,
a load switching unit capable of connecting/disconnecting the loads to the solar array junction box based on voltage of the batteries,
a power path selection unit capable of prioritising and selecting the source of power from any one solar photovoltaic system and grid power for charging the batteries, wherein, the power path selection unit diverts the input of the batteries from the solar arrayjunction box to grid power upon receiving a signal of nonavailability of sunlight from the sensor unit, and
a central control unit controlling and monitoring the sensor unit, the battery charge monitoring unit, the load switching unit and the power path selection unit.