Drainback solar hot water systems are not as flexible as pressurized systems, but still work very well in both residential and business applications. They are very efficient if they are planned and installed carefully.
These systems have many advantages:
It's also important to consider these disadvantages:
Drainback installations use three tanks to heat the domestic water supply. The two main tanks are just like those used in pressurized solar thermal systems. However, the third is specialised – the drainback tank, which is installed on the solar loop.
The two main tanks are installed in standard fashion: the one heated by solar energy is piped in series before the backup grid-tied tank, so that the sun-heated supply is topped up with heat in the second tank if necessary.
As soon as you start looking into a solar thermal installation, you will run into certain terms and principles that may be unfamiliar. It is essential that you understand these ideas, so that you can see what is needed and make intelligent decisions when offered choices by professional installers.
One of the advantages of a pressurized solar hot water system is that the solar loop is always full. This means that the pump has no static head pressure to overcome (just friction head), so low-head, slow-starting pumps can be used effectively. And those pumps can be run on power from a PV array, eliminating your grid-tied power costs for operation.
Energy, pollution and climate change are familiar terms to most people, but what do you really know about smog, greenhouse gas emissions, and climate change?
Hydro-electric Power Stations
One of the more widely used renewable energy sources used today is hydro-electricity. The hydro-electric power plant gives off very little emissions and no direct waste. Hydropower currently generates 20 percent of electricity globally, accounting for almost 88 percent of the electricity that comes from renewable sources.
Gas fired power plants
Power stations using gas have a much smaller carbon footprint than that of coal. Moreover, the gas is piped straight to the power stations, lowering secondary carbon emissions because no transportation is involved in its delivery.
Of all of the methods for generating electricity, the one responsible for emitting the highest amount of pollutants into the air is the method employed by coal fired power stations. Still, coal fired power stations are used to generate about 41 percent of the electricity used globally. In the U.S., about 49 percent of electricity is generated by coal.
Every country uses various types of fuel in their power stations to generate electricity for power. America, India and Australia depend heavily on coal, while France depends on nuclear power, and Sweden and Norway use hydro-electric to power most of their electricity.
This variance in types of generation results in many different volumes of emissions, the amount of which are significant in their quantum according to each country’s production of electricity.
