A 12V, 2.4W battery less solar power controller (BLSPC), capable of driving load at constant low power, has been proposed, designed and practically implemented with minimal efficiency sacrifice irrespective of solar radiance variation. This device utilizes power electronic circuits, more specifically a Buck-Boost DC-DC converter along with Maximum Power Point Tracking (MPPT) algorithm to perform the desired task. Starting from 100w/solar radiation the controller can provide constant power 2.4 watts at 12V without using any storage facilities. The output voltage can be adjusted to any desired level from 0V to 12V DC depending on the application at consumer premises. In this work, efficiency up to 90% at shadow weather phenomenon has been achieved. Moreover, this power controller can be used in consumer premises for direct-coupled system with solar panel irrespective of solar radiation variance.

1. 1/18/2019 1
Battery Less Solar Power Controller to Drive Load
at Constant Power Irrespective of Solar Radiation
Presenter
Sajib Sen

2. Outlines:
• Objectives
• Background
• Proposed Prototype of a Battery Less Solar Power Controller
• Power Controller Operation
• Results and Discussion
• Advantages
• Conclusion
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3. • To implement a solar power controller prototype which has fixed
output power with varying voltage and current according to load
demand at consumer premises.
• Maximum efficiency of the controller during abrupt weather or
shadow condition.
Objectives
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4. • World energy demand will increase up to 53% by
2035(source:U.S. Energy Information Administration).
• Special legislation on energy for carbon emission,
which came into effect in 2003, forces energy
producers to look at cleaner forms of generating
electricity in order to combat global warming caused
by green house gases.
• Most rural areas do not have access to electricity, and
to provide electricity in these areas by increasing the
scope of the electrical grid is often costly and has
challenges .
• Thus stand-alone renewable energy system (like as PV
system) is very suitable for remote areas as well as
clean source of energy.
Background
Fig. 1. World 𝐶𝑂2 emissions from fuel combustion.
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5. Stand-alone Conventional PV system:
Storage system(Battery)
Background(Continued..)
Fig.2: Stand-alone conventional PV system
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6. Standalone PV system without storage facility:
• Battery cost has been saved.
Fig.3: Solar driven water pump (SDWP)
Fig.4: Solar powered electric vehicle (SPEV)
Fig.5: Solar powered rice mill (SPRM)
Background(Continued..)
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7. Assume, suddenly the Sun is covered by some clouds for some moments which
caused less penetrating of solar radiance for battery less solar driven water pumps
(SDWP), solar powered electric vehicles (SPEV), solar powered rice mills
(SPRM) etc. than before.
Effects:
• Cause stability of these system by several levels of voltage fluctuation.
• May cause permanent failure for some critical loads also.
A controller which can handle this situation can only make the PV system without
storage facility stable as well as more cost effective than the conventional.
Background(Continued..)
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8. Fig.6: Block diagram of the proposed Battery Less Solar Power Controller (BLSPC)
Proposed Prototype of a Battery Less Solar Power Controller
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9. • For simplicity, a load as DC 12V,2.4W had been assumed to be drive.
• To keep power constant at the load end when solar panel voltage fall below
12V a trade-off between panel voltage and current had been made.
• This tradeoff was performed by a microcontroller and a DC-DC converter.
• For this prototype a voltage variation of 7V to 25V for solar panel had been
considered.
Proposed Prototype of a Battery Less Solar Power Controller(Continued..)
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10. Fig.7: Flow chart for microcontroller operation of the proposed BLSPC.
Proposed Prototype of a Battery Less Solar Power Controller(Continued..)
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11. :
PV power
generation
Boost Circuit
Status
Buck Circuit
Status
𝐕 𝑃𝑉 > 𝐕𝐿𝑂𝐴𝐷 Idle Operating
𝐕 𝑃𝑉 < 𝐕𝐿𝑂𝐴𝐷 Operating Idle
𝐕 𝑃𝑉 = 𝐕𝐿𝑂𝐴𝐷 Idle Operating
Power Controller Operation
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12. The solar panel used here has the following parameters: 𝑃𝑚𝑎𝑥 = 20W, 𝑉𝑜𝑐= 22.16V, 𝐼𝑠𝑐=
1.21A, voltage at 𝑃𝑚𝑎𝑥 (𝑉𝑚𝑝) = 18.35V, and current at 𝑃𝑚𝑎𝑥 (𝐼 𝑚𝑝) = 1.09A for standard
operating condition 1000W/𝑚2at 250C.
Result for 12V, 2.5W DC load when solar panel output voltage is less than the requirements
of the load:
Solar
radiation
(W/m2)
Solar
Voltage
(V)
Solar
Current
(A)
Solar
Power
(P)
Load
Voltage
(V)
Load
Current
(A)
Load
Power
(P)
Efficiency (%)
100 8.8 0.30 2.64 12.0 0.20 2.40 90.9
210 9.2 0.32 2.94 12.0 0.20 2.40 81.6
320 10.1 0.34 3.43 12.0 0.20 2.40 70
405 11.0 0.41 4.5 12.1 0.20 2.42 53.3
535 11.9 0.48 5.71 12.2 0.20 2.44 42.03
Results and Discussion (Continued..)
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13. Solar
radiation
(W/m2)
Solar
Voltage
(V)
Solar
Current
(A)
Solar
Power (P)
Load
Voltage
(V)
Load
Current
(A)
Load
Power
(P)
Efficiency
(%)
600 12.5 0.53 6.625 12.0 0.20 2.40 36.2
745 13.8 0.61 8.418 12.0 0.20 2.40 28.5
890 14.7 0.69 10.1 12.1 0.20 2.42 23.8
Results and Discussion (Continued..)
Result for 2.5W DC load when solar panel output voltage is more than the
requirements of the load:
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14. 8.8 9.2
10.1
11
11.9
12.5
13.8
14.7
0.3 0.32 0.34 0.41 0.48 0.53 0.61 0.69
0
2
4
6
8
10
12
14
16
0 100 200 300 400 500 600 700 800 900 1000
Solar Radiation(W/𝑚^2)
Solar Voltage (v) Solar Current(I)
Fig. 8: Panel power dependency with solar radiation
Results and Discussion (Continued..)
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15. 2.4 2.4 2.4 2.42 2.44 2.4 2.4 2.42
90.9
81.6
70
53.7
42.7336.2
28.5 23.8
0
20
40
60
80
100
0 100 200 300 400 500 600 700 800 900 1000
Solar Radiation(W/𝑚^2)
Load Power(w) Efficiency(%)
Fig. 9: Proposed controller efficiency with solar radiation
Results and Discussion(Continued..)
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16. • It can ensure to continue operation in a small clinic of remote costal or island area having critical
load (like as 12V,2.4W DC) which are sensitive to voltage fluctuation.
• It can provide stability for robust integration between renewable energy sources in remote areas.
• This type of power controller can be used directly for hybrid grid tied power system, providing
stability and cost effectiveness than conventional hybrid grid tied power system.
• This controller utilizes minimum generation and maintenance cost.
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Advantages

17. • This Prototype is used in the laboratory to drive a 12V 2.5W DC load without using battery
irrespective of solar radiance variation from 100 W/𝑚2 to 900 W/𝑚2.
• Some efficiency has been sacrificed for higher solar radiation to maintain constant power at the
load end.
• Though conventional PV system shows more efficiency than battery less PV system, it’s
stability and performance changes in different conditions.
•
• Inclusion of solid-state switching devices such as MOSFET instead of relay, may provide faster
load switching to supply uninterruptable power to desired load.
• Using inverter and Step up Transformer, this controller can provide constant power to the
National Grid.
Conclusion
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18. Questions?
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