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Topics: Off-Grid Solar PV systems on Solar Energy
Start by
Sanjayan Marat
01-01-2014 10:33 PM

Off-Grid Solar PV systems

Is 1 KWp off-Grid Solar PV systems (1000 Wp Solar PV Modules, 1 KW Mppt built in PCU and 7200 Whr capacity batteries) can save money (based on the Indian - Kerala state electricity tariff) or not? In Kerala the house owners consume less than 3 KWhr/day charges are average Rs 3/- per KWhr
Proposed system sizes 1000 Wp Poly crystalline Modules (25 Years Warranty), 1 KW - MPPT built in Power Conditioning Unit (5 Years warranty) and batteries to store 7200 Whr (5 Years warranty)
Approximate cost is Rs 180,000 and government provide 50% subsidy upfront
According to the present market costing I believe, the user need to spend Rs 128,298/- at the end of every 5 years until the PV panels life time of 25 Years
So the user need to spend Rs 128,298 x 4 = 513,190/-
(the assumptions are after 5 years the battery and PCU can fail any time and need replacement, as per current market rate PCU minimum cost is Rs 30,000/- and Battery 60,000/-)
Please share your expertise opinions in this matter
01-02-2014 01:00 AM
Top #2
K. Sobhan Babu
01-02-2014 01:00 AM
hi sir,
what's with the 1,28,298 money.. Are you planning to change the panels every 5 years ??
For every 5 years only batteries need to changed. As you have warranty you shouldnot worry about problems within that period.
01-02-2014 03:20 AM
Top #3
Michael Brown
01-02-2014 03:20 AM
Bad stand alone design. Minimum 3 times the daily consumed kw should be the pv size. Minimum 4 times the daily consumed kw should be the storage size. Go smaller and the batteries will never make it much more than a year.
01-02-2014 05:33 AM
Top #4
Michael Brown
01-02-2014 05:33 AM
Bad stand alone design. Minimum 3 times the daily consumed kw should be the pv size. Minimum 4 times the daily consumed kw should be the storage size. Go smaller and the batteries will never make it much more than a year.
01-02-2014 08:01 AM
Top #5
Michael Brown
01-02-2014 08:01 AM
As far as warranties are concerned, you will quickly go poor doing service and ruining your reputation if your job breaks down all the time.
01-02-2014 10:49 AM
Top #6
Sanjayan Marat
01-02-2014 10:49 AM
Hi Sobhan Babu,
Thanks for responding, I need more people to discuss this matter in order to avoid the mistakes in future programs
The project is from ANERT (Kerala Govt's Renewable Energy Authority) and MNRE subsidized Program
My intention is to illustrate the reality of tax payers money and time wasted (in my opinion) and generating the bad remarks within public about RE especially PV systems and this will add fuel to the present solar scams happened in Kerala

Here follows the calculations:

24 Companies are empaneled (only 2 from Kerala) and authorized to supply, Install and maintain the system. The key conditions are as follows:
1. The solar panels and the BOS must have the with MNRE specified approvals and guaranteed 25 years according to STC criteria (I have noticed some installations used painted mild steel structures! will this last 25 years?)
2. PCU is guarantee - 5 Years, after 5 year any time it can fail and may be repairable or may not be, so consider minimum Rs 30,000 for replacement or else need to consider 10% as AMC / year (I agree with you and not considering any maintenance charge by assuming it will serve 25 years!!)
3. Battery guaranteed for 5 year (first of all this is wrong, battery cannot be guaranteed for years, the life of the battery must be calculated by charging and discharging cycles) it is 100% sure the batteries will not last more than the warranty period so 7200 Whr capacity battery will cost 60,000
4. The suppliers are pretending / as per ANERT guidance only 5 visits required during the 5 year period, it is mandatory to use the system minimum 5 years as per ANERT guidance! after 5 years what???!!!

Let us calculate:
As greed by the empaneled companies the total charge customer pay to the supplier are in the range of Rs 85000 - 110000, let us average it to Rs100,000 plu ANERT Subsidy 39,000 plus MNRE Subsidy 53262/- which in total Rs 92262/-

Companies receive total (average) - 192262/- for the 1000 Wp Polycrystalline Panels, 1 KW PCU, 7200 Whr (24 V, 300 Ah) batteries and BOS which are fixtures, cables connectors, earthing etc.

Customer spend Rs. 100000/-

First 5 years - No other expense except (if everything normal) the bank interest of the initial amount - Let us calculate the nationalized bank term deposit interest 9%

Initial expense interest = Rs 45000/-
First 5 year daily expense = 365 x 5 = 1825 days, 45000/1825 = Rs 24.66 per day

Second 5 year - assume PCU OK, but battery has to change, because it will complete the charge discharge cycle
12 V/150 Ah- C10 battery - 4 nos = minimum Rs 60000/-

= 60000/1825 = Rs 32.90 - per day, so 32.90 + 24.66 = Rs 57.56/- per day
This will follow the 3rd, 4th and 5th five years
So 20 years (7300 days) need to spend a total of = Rs 420,188 and the first five year 45000/- = total Rs 465,188/- (provided the Inverter did not give any trouble)

The generated energy is maximum 3.6 KWh / day and total (25 year x 365 = 9125 x 3.6 = 32850 Kwhr
Per unit (Kwhr) cost = 465188 / 32850 = is Rs 14.17 Rs - for the customer and + almost the same through the subsidy (tax payers amount), so total spending > Rs 28/- per unit!!

This if the authorities provide grid tied Roof top SPV power plant by spending the subsidy money for net-metering and the distribution facility enhancement, the yield will be more
The total amount anticipated to spend for subsidy is = Rs 92,26,20,000/- !!!

Please correct me if I made any mistake in the calculation and any wrong understanding about the program
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