Wednesday, October 31, 2012

Economics of your electricity bill


Benefit in investing in your own electricity Vs investing the same amount in a fixed deposit

Let’s consider two persons A and B who are having Rs. 25,000/- monthly electricity bill. The all inclusive investment for solar electricity generation system that can wipe out this Rs. 25,000/- electricity bill is Rs. 2,200,000/- (Rs. 2.2 Million)

A invests Rs. 2.2 Million in a solar electricity generation system

B invests the same amount in a fixed deposit at a rate of 14% per annum
 
The future of A


Monthly Consumption
600
 

Monthly bill (Rs)
24998.85

New bill (Rs)
142.50

System capacity
5.00

Investment
2,150,000

Monthly Saving
24,856

Annual Increase in tariff
0.19


Year
Monthly Saving
Annual saving
Accumulated Saving
 Recover of investment

Standard Warranty Period
1
24856
298,276
298,276
-1,851,724

2
29579
354,949
653,225
-1,496,775

3
35199
422,389
1,075,614
-1,074,386

4
41887
502,643
1,578,257
-571,743

5
49845
598,145
2,176,402
26,402

6
59316
711,793
2,888,194
738,194

7
70586
847,033
3,735,227
1,585,227

8
83997
1,007,969
4,743,197
2,593,197

9
99957
1,199,484
5,942,680
3,792,680

10
118949
1,427,385
7,370,065
5,220,065

11
141549
1,698,589
9,068,654
6,918,654

12
168443
2,021,320
11,089,975
8,939,975

Extendable Warranty Period
13
200448
2,405,371
13,495,346
11,345,346

14
238533
2,862,392
16,357,738
14,207,738

15
283854
3,406,246
19,763,984
17,613,984

16
337786
4,053,433
23,817,418
21,667,418

17
401965
4,823,586
28,641,003
26,491,003

18
478339
5,740,067
34,381,070
32,231,070

19
569223
6,830,679
41,211,749
39,061,749

20
677376
8,128,509
49,340,258
47,190,258


21
806077
9,672,925
59,013,183
56,863,183

22
959232
11,510,781
70,523,964
68,373,964

23
1141486
13,697,829
84,221,793
82,071,793

24
1358368
16,300,417
100,522,210
98,372,210

25
1616458
19,397,496
119,919,707
117,769,707

  
The calculation in above table is done as follows.
  • The monthly consumption is 600kWh and that is a Rs. 24,998/- electricity bill 
  •  After installing a 5kWp solar electricity generation system, the new bill is Rs. 142/- only.  There for he will start to save his entire electricity bill 
  • The investment for the system is Rs. 2.150 Million. 
  • The annual increment in electricity tariff is taken as 19%
According to the results we can see that A will recover his invested Rs. 2.150 Million from the saving of his electricity bill in just 5 years. That means after this point he start to get free electricity and also there are no risks for the equipment because they are still under warranty.

The inverters warranty period is 12 years. At the end of inverters warranty period A have saved Rs. 8.94 Million. If A buy the inverter with extended warranty of 20 years, then at the of inverters warranty period he will save Rs. 47 Million 
 
At the end of the warranty period for solar panels, that means after 25 years later A have saved Rs. 117.77 Million. That is he invested Rs. 2.150 Million and saved Rs. 117.77 Million in 25 years. That is a gain of 55. At the end of 25 years, it will be equal to saving Rs. 392,566/- a month.

The advantage of this saving is you no need to pay any taxes to these Rs. 117.77 Million.


The Future of B

There you can see how B loses money. That is because even he gets interest for his fixed deposit, he have to spend an amount greater than that for electricity. So even he saves at the bank, he is spending greater than that at home. So the net saving is actually a lost.

There for after 12 years later B has lost Rs. 750,000/- and after 25 years later his loss is Rs. 12 Million.

If B wants to match the two investments, he must have a guaranteed interest rate of 19% per year for the next 25 years.

Therefore investing in your own electricity is beneficial than investing in fixed deposits.



Interest rate
14%

Investment (Rs)
2,150,000

Year
Investment
Interest
Accumulated Total saving in each year
The hole in saving, Electricity bill
Amount B lose in every year



1
2,150,000
301,000
2,451,000
298,276
2,724

2
2,451,000
343,140
2,794,140
354,949
-11,809

3
2,794,140
391,180
3,185,320
422,389
-31,209

4
3,185,320
445,945
3,631,264
502,643
-56,698

5
3,631,264
508,377
4,139,641
598,145
-89,768

6
4,139,641
579,550
4,719,191
711,793
-132,243

7
4,719,191
660,687
5,379,878
847,033
-186,346

8
5,379,878
753,183
6,133,061
1,007,969
-254,786

9
6,133,061
858,629
6,991,689
1,199,484
-340,855

10
6,991,689
978,837
7,970,526
1,427,385
-448,549

11
7,970,526
1,115,874
9,086,399
1,698,589
-582,715

12
9,086,399
1,272,096
10,358,495
2,021,320
-749,225

13
10,358,495
1,450,189
11,808,685
2,405,371
-955,182

14
11,808,685
1,653,216
13,461,901
2,862,392
-1,209,176

15
13,461,901
1,884,666
15,346,567
3,406,246
-1,521,580

16
15,346,567
2,148,519
17,495,086
4,053,433
-1,904,914

17
17,495,086
2,449,312
19,944,398
4,823,586
-2,374,273

18
19,944,398
2,792,216
22,736,614
5,740,067
-2,947,851

19
22,736,614
3,183,126
25,919,740
6,830,679
-3,647,554

20
25,919,740
3,628,764
29,548,503
8,128,509
-4,499,745

21
29,548,503
4,136,790
33,685,294
9,672,925
-5,536,135

22
33,685,294
4,715,941
38,401,235
11,510,781
-6,794,840

23
38,401,235
5,376,173
43,777,408
13,697,829
-8,321,657

24
43,777,408
6,128,837
49,906,245
16,300,417
-10,171,580

25
49,906,245
6,986,874
56,893,119
19,397,496
-12,410,622



For free consultation on your electricity bill and energy saving tips, please contact :
Tel. : 011 278 7564    Mobile:  077 831 4973      Website : www.jlankatech.com 


2 comments:

  1. Very impressive analysis. 70% of the CEB Domestic consumers consume less than 70 kWh/month. There are very few domestic consumers who consume like 600 kWh/month in Sri Lanka.
    Even the average consumption in High consumption Colombo Domestic consumers only consume about 200 kWh/month. The Total average consumption of all consumers in Colombo city works out to 655 kWh/month where as the same for all CEB domestic consumers is just 68 kWh/month.
    So it will be better to workout the tables with a 1 kW system for a domestic consumer to reduce his consumption just below 90 kWh/month to show the Maximum impact. These could be worked with the recent 50% reduction in price announced by JLanka to show the benefit of larger number of consumers. Best wishes.
    (All figures quoted are from CEB 2011 Statistics available in CEB web site.)

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