My Solar Energy Harvesting Begins to Bear Fruits

After a few months of Solar harvesting, my electricity usage has began to come down for the past 3 months. I recon that I am able to save about 100 kWh of electricity per month (Refer to my own record of actual electricity usage).
Based on current tariff of S$0.28 or 28 cents (inclusive of 7% GST), I estimate that I would be able to save S$28 per month which means I am able to recover my cost within 4 years.

But part of the reason for the electricity usage to come down could be because of the cold weather we experienced in Singapore these 2 months. The cold weather has resulted in lower usage of air conditioning. I would have to monitor the usage during hotter months, but for now I am quite happy with the result.

The higher gas and water usage shows that I am not on holiday during this period. I still wonder why my gas usage shoots up so high ??

Month	Amount	Est (*)	Own record	Electricity (kWh)	Gas (kWh)	Water (Cu M)
Jul-13	$152.85	*		372	49	13.3
Aug-13	$202.92			515	65	17.3
Sep-13	$180.03	*	413	451	58	15.6
Oct-13	$145.71		399	347	50	13.5
Nov-13	$151.29	*	349	367	50	13.4
Dec-13	$141.01		306	280	80	17.1

Update:
My electricity consumption has dropped to 73kWh in Feb, believe it or not?
Of course not. The actual reading is 170kWh, they had over estimated in Jan and made adjustment in Feb. I think it will stabilized to around 200kWh. That's a saving of 200kWh per month or $56 per month or $672 per year, which is 100% more saving than I expected.