Solar Photovoltaic ElectricityIndian Perspective-2010

• The Jawaharlal Nehru National Solar Mission, is a major initiative of the Government of India and State Governments to promote ecologically sustainable growth while addressing India’s energy security challenge.

• It will also constitute a major contribution by India to the global effort to meet the challenges of climate change.

• This is one of the several initiatives that are part of National Action Plan on Climate Change. The program was officially inaugurated in 2010 by Prime Minister of India, Manmohan Singh.

JAWAHARLAL NEHRU NATIONAL SOLAR MISSION

PV systems • are easily transportable and Installable. • can be used to generate electricity

where it will be used, • even at locations the electric grid

doesn’t reach. • PV is also modular, so installations can

be scaled to the appropriate size for a given use

Small as well as medium scale

• PV’s scalability allows it to be used for both large-scale power plants and to

• power handheld calculators, and it distinguishes PV from fossil fuel based power.

• PV can be installed on buildings, parking lots and other developed areas without interfering

with human activities.

Solar energy can be integrated into virtually every part of Indian life—• the homes we live in, • the offices where we work, • the farms and factories that produce the

products we buy, and • the schools where our children learn. • With creativity and sound public policy,

solar energy can make a major contribution to India’s energy future.

In solar photovoltaics, sunlight is converted into electricity using a device called solar cell

• A solar cell is a semiconducting device made up of silicon or other materials, which when exposed to sunlight, generates electricity.

Magnitude of the current generated depends on

The Thar Desert in India is also a promising location for a solar energy.

An example of a complete set of beam normal insolation data for a given location is shown in Figure

Capacities of SPVmodules

• SPV modules of various capacities are available, and are being used for a variety of applications. Theoretically, a PV module of any capacity (voltage and current) rating can be fabricated. However, the standard capacities available in the country range from 5 Wp to 120 Wp. The voltage output of a PV module depends on the number of solar cells connected in series inside the module.

Science & technology of solar Cells & Modules

Types of silicon solar cells

(Mono- crystalline, multi- crystalline, and Amorphous, Thin film)

Energy efficiency

Energy efficiency

• A solar cell's energy conversion efficiency (η, "eta"), is the percentage of power converted

(from absorbed light to electrical energy) and

collected, when a solar cell is connected to an

electrical circuit. This term is calculated using the

ratio of Pm, divided by the input light

irradiance under "standard" test conditions (E, in

W/m2) and the surface area of the solar

cell (Ac in m²).

Standard Current-Voltage (I-V) Curve

• The I-V Curve is an important technical aspect

of a solar module, the basis for understanding

all PV array design. It represents the possible

values of output current (I) and voltage (V)

that a solar module can deliver under specific

environmental conditions.

Standard Current-Voltage (I-V) Curve

Reading the I-V Curve

• If the module is outputting to a 12-volt battery, you can determine the watts output to the battery from the graph. Read up from 12 volts to the IV curve and then over to the

Amperes scale to find that the current output

would be about 5.9 amps. Since power (in

watts) equals voltage times current, this

means that the module would be outputting

into the battery at a rate of about 71 watts.

Inverter fundamentals

• The inverters transform the DC power from

solar modules into AC power to match the grid

and be useful for most house loads.

• The inverter is a power conditioner that creates

pure sine wave power (AC.) This power is

cleaner than the grid because it is conditioned

right on site.

Maximum Power Point Tracking (MPPT).

• Inverters also maximize the power output of the solar array in a function known as Maximum Power Point Tracking (MPPT). Solar modules produce the power at the voltage they are connected to.

• The maximum power point voltage changes as the sun moves throughout the day and the current (amps) gets higher and lower.

• This allows the inverter to produce the most amount of power at any given time without frying its circuitry.

Inverter failure

• Inverters are the one component that needs to be replaced periodically. Most systems installed today use a single inverter for the entire system, so when it fails, the whole system stops providing electricity to the home.

• Possibly with an inverter for each panel or small group of panels may be a solution. This has several advantages:

• If an inverter fails, only one panel of the system will be affected,

which will be reported in our daily monitoring.

• This allows for better scalability, in that we do not need to have

different inverter capacities for different system sizes.

• The efficiency of the system is improved, since DC loses more

energy than AC going through a wire.

Available space

• A crucial factor is having enough space in the sun with the proper orientation.

• The average home needs about a 5 kW system to offset their annual usage.

• To calculate the physical size of this system, you can use this simple rule of thumb:

• 10 W / ft2 of space

• A 5 kW system covers about 500 ft2 of roof or ground area.

• 5000 W / 10 W/ft2 = 500 ft2

Charge controllers/regulators -1

• Why do you need a controller?

• Main function is to fully charge a battery without permitting overcharge. If a solar array is connected to lead acid batteries with no overcharge protection, battery life will be compromised. Simple controllers contain a relay that opens a charging circuit terminating the charge at a pre-set high voltage and once a pre-set low voltage is reached, closes the circuit, allowing charging to continue.

Charge controllers/regulators - 2

• More sophisticated controllers have several

stages and charging sequences to assure the

battery is being fully charged. The first 70% to

80% of battery capacity is easily replaced. It is

the last 20% to 30% that requires more

attention and therefore more capacity.

Charge controllers/regulators -3

• The circuitry in a controller reads the voltage

of the battery to determine the state of

charge.

• Designs and circuits vary, but most controllers

read voltage to reduce the amount of power

flowing into the battery as the battery nears

full charge.

SPV Power Plant

solar electric generating plant

• The largest solar electric generating plant in the world produces a maximum of 354 megawatts (MW) of electricity and is located at Kramer Junction, California. It produces electricity for the grid supplying the greater Los Angeles area.

Standards for balance of system components

Located at the 19th Milestone on the Gurgaon–Faridabad road just outside the boundary of Delhi.

• Solar cell testing

• Photovoltaic module testing

• Testing of lighting systems

• SPV pump testing

• Battery testing for PV applications

• Long-term performance evaluation of PV modules

• Resource assessment

• Technology demonstration & assessment

• SPV power plant

• Research and Development

PV power output management can be achieved with battery or other electrochemical storage, pumped hydroelectric storage, or with diesel-

generator backup.

The top five in solar technology utilisation for Solar PV Grid connected are:

GermanyJapanU S ASpain France

Issues in managing solar electricity: References

• Denholm, P and R. M. Margolis, 2007, ‘Evaluating the limits of Solar Photovoltaics in Traditional Electric Power Systems’, Energy Policy, Vol 35, pp 2852 - 2861

• Denholm, P and R. M. Margolis, 2007, ‘Evaluating the limits of Solar Photovoltaics in Electric Power Systems Utilizing Energy Storage and other Enabling Technologies’, Energy Policy, Vol 35, pp 4424 – 4433

• Lamont, Alan, 2008, ‘Assessing the Long Term System Value of Intermittent Electric Generation Technologies’, Energy Economics, , Vol 39, pp 1208 –1231

Comparison of PV and Diesel-generator power

• Kolhe, Mohanlal, Sunitha Kolhe and J.C. Joshi, 2002,

“ Economic viability of stand alone photovoltaic

system in comparison with diesel powered system for

India”, Energy Economics, vol24, pp 155 – 165.

• Stand alone PV systems in remote areas of India are compared with the diesel-powered systems through sensitivity analysis. PV systems are found to be the lowest cost option for the daily energy demand of 15 kWh/day under unfavourable economic conditions and upto 68 kWh / day under favourable conditions.

An important reference book for PV Systems

• Practical Handbook of Photovoltaics: Fundamentals and Applications

Edited by: Tom Markvart and Luis Castaner

[2003]