There are three ways of calculating solar savings.
1) Your solar inverter should tell you the units of electricity the system generated in a day. For example, if your 4kw solar system generated 16 units of electricity in a day and each unit of electricity costs Rs. 7 then you made Rs. 112 worth of electricity in day. If you multiply that with 365 you get Rs. 40,880 which is your annual savings from solar.
2) You can also compare the cost of solar to cost of running a diesel generator. A 10kva diesel generator consumes 1.5 litres of diesel every hour. If you live in an area that gets regular long powercuts of 10 hours then you will end of spending nearly 22,500 per month on diesel as diesel costs between Rs.50-60. Whereas, a 10kw off-grid solar installation would cost much less. You will be able to recover the cost of solar installation just 5 years if you compare it with using diesel generators.
3) In the case of grid-tie solar, you can also calculate the units of solar electricity you sell to the Government through bi-directional meter. For example, in Bangalore, the electricity board pays more than Rs. 9 for every unit of electricity.
For more Details contact Ricans team for free cost analysis !!