On mini-grid: Some questions

The write-up on renewable energy by Dr. Ahmed published in your daily on 7 February 2015, is thought-provoking. The write-up has some novelty about it, although a few questions about solar mini-grids can be pertinently raised. The technology has been in use for quite sometime and I first read about it a few years ago.

I doubt if the technology is ultra-modern as termed by the writer. The only new thing about it is about payment for power consumption by card. If we adopt this method of payment, the problem of unpaid electric bills may be solved and the cost and hassle of snapping connections can be avoided. It also makes the user more conscious about power conservation and can encourage power saving.

The picture of panels shown in the article, are all photovoltaic panels that are actually activated by sunlight and not solar heat. In some places, lenses with mirrors and reflectors are used that provide steam and set electric turbo-generator to producing electricity. The electricity generated by the photo-voltaic panels is DC which has to be converted to AC by inverters. Usually the DC can also charge storage batteries and through an inverter, converts it to AC, which many of us may be using at home and offices, given the poor reliability of power supply in the country.  

The same principles can be used on a large scale with back-up DC batteries. The panels can directly power the mini-grid during daylight and also have enough capacity for charging batteries, so that the need for night time power is met. Conceptually it is a mega battery inverter set that has been in use in Bangladesh for some years now.

The only difference in this case is, instead of connecting it selectively to the house wiring, it is connected to a rural mini-grid, that supplies power to a number of households and irrigation pumps, small rice mills and machine shops.

I appreciate the writer for presenting a rare topic on newspaper pages.

Engr. S.A.Mansoor

Dhaka.