FIELD OF INVENTION
The invention relates to a load priority system for solar photovoltaic
applications, which aims at efficient use of solar energy.
BACKGROUND OF THE INVENTION
There is a growing interest in using environment friendly energy
sources. Solar photovoltaic is one of the attractive options among
them. However, due to high cost of solar modules, it is not yet
affordable by general public. Moreover, the solar light is available in
the daytime and that too varies from very low to high level of
radiation depending on the time of the day and condition of the
weather. Hence, the batteries become the second costlier component
for smoothening these variations and provide electric power in the
hours when sunlight is not available. Batteries create recurring
expenditure in the system and increase the requirement of regular
maintenance. Hitherto, a stand-alone system is designed keeping in
view of the average load in which the batteries are usually over
designed to take care of the non-sunny days in mind requiring large
capacity batteries.

However, in offices, schools and health centers, the requirement of
the electric power is mostly in the daytime. Leaving aside some very
critical loads such as emergency lights, a small refrigerator for
preserving medicines etc., other loads like fans etc. are less critical
and can be switched off when generation of solar photovoltaic power
is not enough. These loads can be prioritized and can be controlled
automatically through a load priority system. This way, a load priority
system can reduce the requirement of the batteries to a great extent
'and therefore reduces the recurring expenditure and improves
reliability of the system.
OBJECTS OF THE INVENTION
It is therefore an object of this invention to propose a load priority
system for solar photovoltaic applications, which ensures an optimum

utilization of solar energy for domestic and medium commercial load.
Another object of this invention is to propose a load priority system
for solar photovoltaic applications, which reduces the cost of
recurring expenditure towards battery by automatic control and load
prioritization.

A further object of this invention is to propose a load priority system
for solar photovoltaic applications, which is capable of maximizing the
use of solar energy during day-time when solar power is available.
Still another object of this invention is to propose a load priority
system for solar photovoltaic applications,which is capable of
switching loads depending on intensity of solar energy and priority of
load.
Yet another object of this invention is to propose a load priority
system for solar photovoltaic applications, which automatically
transfers load to the mains (if available) when solar radiation
becomes very low or not available.
A still further object of the invention is to propose a load priority
system for solar photovoltaic applications which adapts environment-
friendly and renewable energy source and thus cheaper.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1- a schematic representation of the load priority system with
load priority controller according to the invention.

Fig. 2- circuit diagram of the load priority system and control circuit
of switching according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF
THE INVENTION
As shown in Figs. 1 and 2, the present invention provides a load
priority system basically configured with the following specifications
of components.
1. SPV Module (4): 24V, 600 W
2. Regulator circuit (3)
3. Load priority control module (1) comprising-:
i) Sensor Module (5): 4 watt
ii) Inverter (2): 12-24V, 625VA
iii) Sensing switching circuitry
iv) Relays (R3, R4, R5) for connecting and disconnecting
loads,
v) Meters (not shown) for displaying the inverter voltage,
current, load voltage and current,
vi) Indicators (not shown) for charging status of batteries.

4. Three sets of load (I, II & III).
As per block diagram illustrated in Fig. (1) the loads (L1, L2, L3) are
segregated in three groups depending on priorities, e.g. Load 1 (high
priority, supported by low capacity battery) having two emergency
fluorescent lights (120 watt),
Load 2 (medium priority) and Load 3 (Lowest priority) having lights
and fans (300 watt)
The system operates depending on the intensity of the sun from
morning to evening. The loads are switched on sequentially, and at
peak hours at noon, preferably all the three loads are on.
Similarly, in the evening-, the loads are switched off sequentially
depending on the priority. The load with highest priority is kept
always on during daytime and supported by batteries. During clouds
depending on the amount of shading, the loads are selected
accordingly.
As per the circuit diagram illustrated in Fig. (2), the sensor module
(5) monitors the solar intensity and based on the data, the controller
(1) switches on the inverter (2) through a relay R1, and a timer R2
and the regulator circuit (3) for utilization of the solar photovoltaic
source of energy (4) till the solar energy is stable and sufficient to
support at least one load (L1, L2, L3) with highest priority.

SUMMARY OF THE INVENTION
A load priority controller has been developed. The lighting and fan
loads have been segregated in various priorities and a critical load
(emergency lights) is given highest priority. The solar modules and
the loads are designed such that at noontime, all the loads are
supported by the generation of electricity by the solar modules. A
sensor module keeps on monitoring the sun radiation, and depending
on the intensity of the sun from morning to noontime; the loads are
switched on sequentially so that at noontime all the loads are on. In
the afternoon, the loads are switched off in the reverse sequence.
The system works fully in automatic mode.
The load priority system of the invention couples SPV directly to the
load and provides better efficiency. The controller is fully automatic.
The system requires no batteries or minimal batteries for supporting

the emergency load with highest priority. Hence both initial and
recurring expenditure on the batteries is reduced significantly. The
usage of power generated is optimal. The system controller with
batteries, occupies lesser space than prior art stand alone solar
photovoltaic system.

WE CLAIM :
1. A load priority system for solar application, comprising:
- a solar photovoltaic module (4) acquiring solar radiation to produce solar
energy;
- a sensor module (5) for sensing and monitoring intensity of solar
radiation;
- an inverter (2) connectable or disconnectable to the solar photovoltaic
module (4) via a regulator circuit (3) the inverter (2) converting solar
energy to electrical energy, the regulator circuit (3) comprising at least
one relay (R1) and one timer (R2); and
- a control module (1) having at least three relays (R3, R4, R5) with
corresponding contacts for switching on or switching off a plurality of
loads (I, II, III) connected to the inverter (2) based on the intensity data
of solar radiation including generation of solar energy wherein the relays
R3, R4, and R5 are enabled to switch on or switch off the power supply
from the inverter (2) to said loads L3, U and L5 depending on solar
radiation intensity and priority of load.

2. The system as claimed in claim 1, wherein the sensor module (5) is
configured to sense and monitor the intensity of solar radiation, and
wherein the control module (1) on the basis of data received from the
sensor module (5) issues instructions to switch on or switch off the loads
individually and sequentially.
3. The system as claimed in claim 1 or 2, wherein the at least one relay (R1)
and one timer (R2) is provided to switch on the inverter (2) by connecting
directly to the solar power source (4).

ABSTRACT

TITLE : 'A LOAD PRIORITY SYSTEM FOR SOLAR APPLICATION.
The invention relates to the load priority system for solar application comprising: a solar photovoltaic module (4) acquiring solar radiation to produce
solar energy; a sensor module (5) for sensing and monitoring intensity of solar
radiation; an inverter (2) connectable or disconnectable to the solar photovoltaic
module (4) via a regulator circuit (3) the inverter (2) converting solar energy to
electrical energy, the regulator circuit (3) comprising at least one relay (R1) and
one timer (R2); and a control module (1) having at least three relays (R3, R4, R5)
with corresponding contacts for switching on or switching off a plurality of loads
(I, II, III) connected to the inverter (2) based on the intensity data of solar
radiation including generation of solar energy wherein the relays R3, R4, and R5
are enabled to switch on or switch off the power supply from the inverter (2) to
said loads L3, U and L5 depending on solar radiation intensity and priority of
load.