Solar Energy

My cousin Venkatesh dropped in almost without a warning a couple of days ago. We were meeting after about 15 years. He deals with solar energy devices. So some observations while I remember them.

1. In TN, the Govt buys back power generated by wind mills which are all owned by private parties. Because of the recent cyclone and the resultant wind, for a few days there was no powercut in TN.

2. Stability of grid - Ideally all the power generated by windmills (renewable) should be absorbed, but in practice fear of grid tripping has resulted in wind power being turned off.

3. Threat to grid stability is there in Germany also when electricity generated by solar power is pumped into it.
4. About going off grid. I was interested in the applications in the agriculture sector. There are solar panels which are somewhat transparent. They can be the roofs of greenhouses, and the power generated can be used to run a low power water pump + drip irrigation.

5. I was just exploring the possibilities of going off grid at home.The cost is determined by the inverter required which is related to the connected load. That is, the solar dc is converted to 220V AC. Then we can use the existing wiring and devices. Then I realized that major component of the connected load in my case is  from induction cooker, microwave oven, oven and hot plate (I cook on electricity. For a single working woman, it is a big headache to get replacement for gas cylinders.)

6. Theoretically, it is more efficient to use the dc solar power as dc for lighting at least, using LED. If I remember what Venkatesh told me, the storage battery has emf 12V and the solar power output can be designed around 13.8V. So power loss while charging is less. But one would require separate line for the lights. I forgot to ask him, but one would require really thick copper wires to minimize transmission loss from terrace to home & also because of no skin effect, we need to use solid thick wire?

7. Solar cookers- box type, not very efficient and parabolic ones with trackers. The parabolic ones are very good and food can get charred if left unattended.Anyway I have no terrace, but I have a northern wall without any window, but I need a southern wall. OK even if I manage with the society, then there is another cooking system. The parabolic mirrors focus sun light at a point where (....I forget the technical term) is kept which has water and is onnected to a system of copper pipes. So steam is produced under pressure and is piped indoors and can be used for cooking and has been done in the case of some office canteens and hostels. Venkatesh was surprised by my willingness to splurge money, but he doesn't know with what idiocy I lost lot of money trying agriculture. At least it is my own money.

8. There are fans which run on dc, but they have carbon brushes in them which may need frequent replacement. I am willing to learn their mechanism and how to service them. Induction cookers need AC. So in my future farm house, I shall have an open terrace from the kitchen.

9. Then of course there is the less glamorous water heater.