Wind and solar energy generations only depend on natural conditions, therefore only provide must run units such that one could not only depend on them, but considered them as additional units that are especially important as peak units (risky for base load consideration), while hydro energy generations provide huge capacity and can be highly increased in times of favourable weather conditions and technological advancements. Therefore, the consideration of supply is based on merit order, which is first, the supply of hydro energy generation capacity (very cheap and provide huge capacity), then if additional capacities are demanded/needed in the market, wind energy capacity comes in and if it's capacity exhausted then solar (NB: for arid regions the scenario will show another situation in the merit orders). However, wind and solar energy generations are only politically driven by none-specialists that have only market interests that is why more research and innovation are taken to this direction that could not supply the whole capacity needed by the market (more 50% is none renewable energy and will still dominate the market for the next 50 years, if the behaviour still remain the same). While hydro energy generation is cheap and the capacity can be greatly increased through research and innovation (but it requires huge investments), but very little is down in this direction to increase the efficiency and reduce cost of construction (technological innovations) as the other two sources are more prefered and had being attracting investments. This is one of the argueements that one can put forward for political discussions on higher electrical energy prices and the continuous use of high capacity of none renewable energy sources like coal and lignite as well as the problems of climate change potentials. Also dangerious sources of energy generations like nuclear. In competitive markets of electric energy production (not natural monopoly market like many less developed countries), smart investors in the electricity energy production markets can take advantage of hybid systems and favour technological development in hydro power generations as water entergements is also being a potential for use of hydrogen cells for green energy generation and spinning of water using less energy to produce more with increasing efficiencies.

Wind and Solar systems generate electricity with no associated air pollution emission emit some air pollutants uses two energy sources with a variable output that depends on weather conditions. Renewable energy electricity gives importance on technical feasibility of increasing contributions of solar- generated and wind-generated electricity to grids. These resources provide intermittent power which can challenge the stability of electric grids.

wind energy and solar energy cannot be considered substitute to hydropower mainly

• hydro power cover wide range of large scale power network with much higher power capacity above 1000 MW
• hydro power network have vast and major power break down from grid station to primary stations, to substation with mulitiple wider network break down till consumer level and proven to be more efficient that wind and solar
• wind and solar are covered mainly for specific areas, location and with certain distance limits
• hydro involves full functional power generation units with converters, rectifiers, power transformers, primemovers, governor which are high tech power units for power generation functional areas.,,.....

Is has to be a combination of wind, solar and hydro. Neither of the three is able to provide our full energy needs. In addition we shall have to continue the search for safe renewable energy sources.

Simple answer is solar is generally available across most geographic areas, especially populated areas, whereas wind and hydro are geographic specific. Solar is also more adaptable for distributed energy applications such as rooftop solar. That said, wind and hydro are both significant and important energy resources at utility scale. Hydro is probably the most economical and reliable power generation resource where available. Most of the desirable hydro resources (excluding less developed countries) have been harnessed so for new generation we must look to untapped renewable resources such as solar, wind, and other as we address climate change and load growth. Energy storage is the next lynch pin.

Wind and Solar energy are more towards environmental protection. However these energies can not replace Hydro.

Between solar and wind, solar is popular because solar is easily available and no pre-requisition required other than sunlight. For wind one should have good wind speed which is not the case for many areas. Also solar batteries are portable and can be used easily in less space.

Unlike the "one size fits all" solutions of the fossil fuel era (coal fired power plants), the zero carbon future that mankind must embrace to survive will require large scale adoption of a balance of complimentary technologies. Wind, solar and hydro all have a role in this mix, for good reasons already discussed in this forum above.

There's another: Hydrogen. A great energy carrier, and way to balance out the excesses that doing this right will generate.

Up until now, the energy infrastructure to power our homes and businesses was completely different (and based on different fossil fuels), than the transportation system (coal vs oil). In the future, it will be all electric, and the electricity generation needs to be as close to carbon free as possible. There is a huge opportunity in the electrification of everything.

Here's the big vision. You overbuild wind and solar by a large margin, let's say by 2X. Hydro is pretty much built-out in the developed world, but you add more every place you can. And you co-locate solar and wind where the environment allows to save on transmission system costs.

Do this at big enough scale and the economics of mass production will drive the cost of wind and solar to well below the current wholesale cost of electricity. You have a two-tier price system for that electricity. A relatively high price for power that is available when you need it (more or less the current wholesale price of "dispatchable" power) that recovers all of the cost including amortization of the capital assets. And a much lower price for electricity that's available when you don't need it, sufficient to cover O&M (operations and maintenance) plus profit.

You use the low cost energy to electrolyze hydrogen from water which you use to fuel the part of the transportation system that doesn't lend itself to battery power (think planes, trains, ships and about half the autos, trucks and buses).

And, you build a few nuclear plants for baseload. The system I just described doesn't really need baseload power in the conventional sense, but those nukes will set the floor price of electricity high enough that everything else works just fine.

The upfront capital cost of this will be stunning. Might crowd out war as a sink for excess tax revenue. But the long term running costs will be very low, much lower than what we experience today. All up, a good deal for everyone.

Renewable energy has got importance due to low cost expansive, Good for environment, good for health it will be available easily.

With the new efficient and affordable battery storage, both solar and wind are much more viable replacements than before. It's important to remember that even our renewable energy sources have environmental drawbacks. Hydro and wind both affect species migration--hydro affects fish migration while wind affects birds and bats. Wind has relatively high metals use while solar includes rare earth metals which are, of course, rare, which means they can be used up. Overall, all three have a much smaller footprint than any fossil fuel.

We should also remember that not all renewables are effective in all locations. Although both wind and solar are becoming more tolerant to less then ideal conditions, you still need sun for solar power and wind for wind power. As to which is better, that really depends on how much wind or sun you get in a particular area.

Remember Solyndra

Solyndra was a manufacturer of cylindrical panels of copper indium gallium selenide thin film solar cells based in Fremont, California.

Although the company was once touted for its unusual technology, plummeting silicon prices led to the company's being unable to compete with conventional solar panels made of crystalline silicon.

The company filed for bankruptcy on September 1, 2011.
Government subsidies [tax payer funds] lost.

Any thoughts?