This is a very interesting question, and I'm sure there's much research being conducted as Solar PV plays a major role in India's energy policy.

MY OPINION is as follows:The key word here is 'Long Term'. Solar PV is definitely very 'sustatinable' with the decentralization strategy, especially with rural areas in India, as they usually operate on an isolated island model. However, considering the shorter technical & economical life times of available PV modules, it becomes necessary for replacements at the end of their short lifetimes. The replacement of the PV modules after a short duration of 15-20 years would defeat the economical advantage of the technology, when used in large scale.

India, especially in the tropical regions, the availabe full load hours for Solar PV power generation almost overcomes the problem with lifetimes. Thus it is advantageous to consider a hybrid system using the full potential of solar PV for a long term strategy. Micro Hydro or small hydro power plants are much more viable along with solar PV, considering their longer technical and economical life times.

Technically speaking I believe decentralized solar plants are viable solution in rural electrification. Solar pv systems set up in areas which receive adequate amount of irradiation can prove to be boon to the rural areas where they can provide electricity and probably be a part of smart grid in the future. But the problem is the complexity of setting up a solar pv system. Solar PV systems are expensive even with the subsidy the government provide. The government doesnt exactly venture into the energy sector by themselves. Here is where private companies come in. They are given contracts which are used by the company to set up a solar PV plant. But in a rural area, people would hardly be able to pay for the expensive electricity that is provided to them. This makes the private company to extend their grid to areas where there is electricity shortage which further increases the price of electricity which again becomes unaffordable. Also Solar PV systems operation and maintenance gets expensive over the years specially in the storage part. If the system is decentralized, it would require large amount of energy storage equipments which are highly expensive. Unless the government steps into the energy sector, a decentralized solar PV system would not be viable. The cost of electricity can be brought down by the usage of PV system combined with other energy sources such as hydro. But a centralized system is needed to make solar pv system viable

First, what alternatives are there? If you focus on Sustainability really long term, the only known system meeting that criterion is biological, as photosynthetic life has existed on this planet for many hundreds of millions of years. It sustains itself by constant recycling and repair. So let us now consider artificial systems. I regard the financial cost of an energy system as too misleading as it contains too many confounding variables many of which are arbitrary, such as financial interest rates, depreciation rates and so on, and which are usually set to disadvantage renewables and favour the 'cheaper' fossil alternatives. Focus instead on the net energy gain of the system (sometimes called the Energy Yield Ratio, EYR) - and you will find that solar PV isn't too bad; maybe five or ten times over its lifetime (although in its early days it was probably < 1). The other factor to consider is the turnover time, in terms of how fast the system can turn solar energy into, say, electricity. Solar PV is excellent - a few milliseconds. Hydro is probaly weeks or months and fossil fuels are - millions of years. So forget them!

Don't forget that having a government 'step in' to change the financial aspects of PV is equivalent to subsidising them with fossil fuels from which the government draws its resources to intervene in the first place.

Adding to what has been said by the respected colleagues, i think the PV electricity generator is the most appropriate solution for remote areas and later in the populated areas. When you use a distributed supply system then the cost of the transportation and distribution will be saved. You can use also DC loads directly such as lightening by LEDs. In order to save the cost of electric storage in batteries one can try to match the load with the variations of the incident solar radiation which means to concentrate the activities in the day time with mingling loads at night. This is a very important concept for successful use of the solar energy. That to build day activity oriented societies.

I think one can build electricity supply -load systems which are are highly efficient. In the sense one has to rec design the loads to be more energy utilization efficient. This will be through embedding intelligence in such devices. I estimate that it may be a must to use such sources of energy in the future.

On the other side one has to enhance the solar cells and their production cost.

I think there is already plans to intensify the use of the PV system in electricity generation. The leader of these plans are USA and China.

Best wishes

Photovoltaic power plants in Europe have been operating for more than 30 years and continue to provide electricity.

Why would change modules at 15-20 years? The manufacturer's warranty is 25 years.

The modules price is very low, $ 0.50 / Wpico.

Price of an isolated installation is $ 2-3 / Wpico (depends on the solar radiation of the place)

The cost of kWh generated with photovoltaics is lower than the cost of kWh generated with nuclear or gas.

Yes, photovoltaic installations are the ideal solution for rural areas, in India and the rest of the world

To answer your question, a lot will depend on what amount of power is required in the place you want to put the PV and what distance there will be from the panel to the point of end use. Please read my papers on my website, http://www.dcisthefuture.org/publications/ especially the paper titled “An exploration of the technical and economic feasibility of a low powered DC voltage mains power supply in the domestic arena”. It is from 2009 and a lot has changed since then. Please see all my other papers.

Solar PV is a very good option for decentralised generation for remote and rural areas. But cost can be one issue. If there are enough fundings from government, inclusion of PV in rural areas has been lot faster that it is currently. In my opinion it will be worth to consider local availability of the resources e.g. biomass, wind, geothermal and so on.

Yes. But, it causes future infrastructure loading that should be considered. Eventually, the grid will expand and absorb the distributed sources. This causes reliability issues, worker safety problems, etc. Careful planning can mitigate the problems.

It is advantageous to consider a hybrid system using the full potential of solar PV for a long term strategy. The present trend is to use compressed air, which is much viable along with solar PV, considering their longer technical and economical life times

As well as the accumulators, as one of the most important party of equipement, became less costly, the idea of using solar energy in rural territories and anothe less populated aries is considered wery atractive. And not only in India