This month of October 2016 was an extremely satisfying one a decentralised solar electricity system was installed in the Rani Kajal Jeevan Shala school in Kakrana and another along with a solar hot water system in the office in Indore.
Ever since Germany began investing in solar energy in a big way about a decade ago the efficiency and longevity of solar photovoltaic panels has increased greatly with a corresponding decrease in their cost. Moreover, the charge controller device too has evolved. Earlier charge controllers would just direct the solar direct current to the storage batteries and then an inverter would convert the direct current from the batteries into alternating current to be delivered to the load leading to a 20 per cent loss of power in the storage process. However, now there are prioritiser devices which during the day send the direct current from the panels directly to the inverter and through it to the load and only store the excess charge in the batteries for the night. Thus, there is an increase in efficiency due to these prioritisers also as even during the day solar power can be used to reduce grid power consumption without the use of batteries. 1000 watts of electricity from the panels can typically produce 5 kilowatthours (units) of electricity per day. The cost of installation for this inclusive of panels, batteries, power controlling units, electricals and set up is about Rs 100,000. Currently the going rate for retail low tension electricity supply is Rs 7 per unit inclusive of taxes and duties. Thus assuming that the inflation rate of the cost of grid power is equal to the commercial interest rate on the investment and so cancel each other out and that there is a replacement cost of batteries every five years for about Rs 35,000, it will take roughly ten years to recover the initial cost of installation of the solar system and the battery replacement. Thereafter, for the next fifteen years or so, assuming the life of the solar panels to be twentyfive years, the cost will be only that of replacing the batteries every five years.
The economics of solar power are therefore not very encouraging even now and it requires huge subsidisation to popularise it and this is what Germany has done in a big way, given the benefits in terms of climate change mitigation. In India there is talk of subsidies but it is very difficult to actually get them. The subsidies are not given to the consumer directly but to the suppliers and given the culture of corruption in this country this leads to siphoning off of the subsidy and the supply of substandard solar systems to the retail consumer. There is not much support from the government to grow the market for decentralised solar systems either and so it is difficult to find reliable suppliers. The big corporate players in solar energy are not really interested in customising systems to the needs of small users. Especially ones like the Rani Kajal School which have special needs due to their location and the abysmal quality of grid power. After several fruitless interactions with the big corporate players, we finally ferreted out a small supplier in Indore, Dynamique Electronics, being run by a young electronics engineer named Ankit Verma. He has just started out about an year ago and is very hands on and innovative. Unlike the large corporate players who only want to sell their standard systems, Ankit was open to customising for our special needs. So together we designed a custom system and ordered its components from different suppliers so as to get the best quality and efficiency suited to our needs.
As with most other technical projects over the past year or so in the Rani Kajal Jeevanshala, like buying a second hand SUV, constructing a water supply and sanitation system and setting up the internet, the solar power installation too was beset with problems which required out of the box thinking for their solution and provided a good learning experience for all concerned. The critical thing is to connect the panels properly to the batteries and the power controlling unit. Initially Ankit had not come down to do the installation as we decided to do it ourselves so that the staff and children could understand the whole set up as shown below.
However, even though everything was connected properly and electricity was being generated by the panels and sent to the power controlling unit, it was not recognising this power. The problem turned out to be the batteries. Such is the low offtake of decentralised solar systems that solar batteries are difficult to find. Solar batteries are different from the standard inverter batteries because they have to accommodate the frequent charging and discharging that takes place in a solar power system. The batteries that we got from one of the standard companies were low on water and charge. So they needed to be charged properly and so the system did not work initially. So Ankit had to come down to Kakrana and then this was diagnosed and the batteries charged and the system is now working. This just shows how difficult it is to get decentralised solar energy going in the current context.
In the office in Indore there already was an inverter backup. So 500 watts of solar panels were installed and a prioritiser added to this system to generate 2 units of solar electricity per day. However, to utilise this properly some load management is required. The heavy loads like the refrigerator and water pump can be run only during the day when there is good solar power as otherwise they drain the battery very fast. So timers have been installed to allow the running of these loads only during the day when there is solar power supply. A solar water heating system has also been installed in Indore. The technology for this too has improved considerably and it provides water at 70 degrees centigrade in just three hours and then stores it in an insulated tank for use at anytime. In this way this Diwali is going to be a climate conscious one for us in Kakrana and Indore!!