Solar Solutions for Schools
- May 7, 2016
- Posted by: Energiaa
SOLAR SOLUTIONS FOR SCHOOLS
Case: Study of Solar solutions for schools: School in Kanpur, Uttar Pradesh, India
Schools are now powering the youth of today across the face of India but the fact still remains that a lot the schools are without electric power themselves.Electricity in schools should not be a luxury but a right of the students studying there in the sweltering heat year after year. Often the location of school is determined by its proximity to a grid connected area and thus a lot of students either have to travel long distances or don’t go at all. Electricity should be able to reach the School always and not the other way round.
A simpler solution would be to run the load of the school via storage based solar inverter system + available Grid during the day time and the same system can supply to the grid via Net-Metering when School is over or during holidays.
Happy Students + Bright Schools = Golden Future
A possible outcome of this exercise will be that more and more schools will start cropping up in different districts so that the travelling time of students is reduced. Added to this are the benefits that the students learn the value and process of going green at a young age.
Therefore a true solution lies in creating a buffer which is bidirectional and can stand and deliver the energy reliably in a most cost effective manner.
Case Study: Public School in Kanpur to be fitted with 10KW Solar Hybrid System
- Erratic Supply and poor quality of Grid
- Loss of productivity among the students
- Ever increasing cost of diesel (More than 30,000 ₹ per month alone on fuel)
- Regular Maintenance of Diesel Generator Sets
- DG Set running at less than 30% rated capacity causing a decrease in life of the DG Set
- Frequent power cuts of 10 minutes to 4 Hours
- Increasing cost of electricity with Time-Of-Day (TOD)
- Very High fixed charges bringing the electricity bill to > ₹ 8.40 Per Unit
- DG Set running at full day causing degradation in the air quality breathed by the children
- Noise pollution created by the DG set running disrupting studies
Few Things were to be considered before designing the Solar Power System.
- Usable rooftop area of the school ( Not all parts are unaffected by shade)
- Inverter should be able to handle the various surge loads of the school
- The Battery sizing was crucial as to not come up short during examinations or laboratory practical or during some school function.
- Ergonomics of the installation keeping future maintenance and expansion in mind
- Payback period
- Implementation of Net metering
With the scarce amount of Grid Electricity hours available daily, a hybrid system was planned to be installed on the premises to take care of the daily working of the school.
Though initially the plan was to use an off grid inverter system but with the encouragement of Net metering by UPNEDA, a hybrid inverter system was installed.
Time of Day (TOD) charging of the batteries was done with a view to maximise the after-school hours sunshine so as to power the security lights during the Night time as well and not waste useful solar energy.
As the school ran from 8:00 AM in the morning to 2:00 PM in the afternoon daily, the battery bank was to be calculated adequately compensating for various factors like Temperature, Ageing Factor, K Factor, Power Grid Failures etc. The battery make is of EXIDE 120V/150Ah.
Solar panels used were of Waree solar make: 10 KWp and the Inverter from Statcon Energiaa.
- PV Panels: 10 KWp
- Inverter: 10 KWp
- Type of Inverter System: HYBRID Grid Synchronised (ON GRID /OFF GRID)
- Battery Capacity: 120V/ 150Ah
- Most of the total Load consists of Fans and Lighting loads of the Classrooms, Halls, Corridors, and Auditoriums etc.
- One Air conditioner of 1.5T was also a requirement
- The computer lab with a few other offices had PCs which were required to run uninterrupted throughout the day
- Total Peak Load = 10 KWp
Special Features of the System:
- Hybrid Inverter ensures that the battery is at peak charge condition whenever it is called upon.
- Maximum amount of savings is ensured by TRUE POWER SHARING between multiple sources in a prioritised manner due to grid synchronisation. The Solar panel is given the first priority to run the primary and secondary loads and only the deficit that the solar is unable to supply is taken from the grid.
- On days when the School is closed due to holidays or when the Loads are less (in winters); the Inverter can export the excess power to the Grid which with the added bonus of net metering allows the owner for a faster payback period on the Solar System.
- Apart from this backup generators are also kept as an emergency backup, which can switch on automatically by the inverter if all the other 3 sources of power fail to supply the load.
- Batteries can also be charged according to the Time of Day. Electricity charges are different according to the TOD in UP and thus the batteries can be charged via grid during the night when rates are low and utilised during the day time when rates skyrocket, again reducing the payback period.
- A special feature in the inverter is the Night saving mode, here the inverter shuts down after sunset time all working days to cut off the transformers from consuming no load magnetising current, which can amount to losses. The Inverter will switch ON after 12 seconds when the grid does go down but otherwise stay shut down till morning 6AM
BLOCK DIAGRAM OF THE HYBRID SYSTEM
- INITIAL INVESTMENT
- PV Panels: 60cells; 10KW= 3,87,600 ₹
- Inverter: 10 kVA= 1,26,250₹
- Batteries: 2Vx60 /150Ah = 1,45,958₹
- Mounting structure= 85,400₹
- Installation and commissioning= 67,000 ₹
- TOTAL= 8,60,165 ₹
- SAVINGS & PAYBACK PERIOD
- Per unit cost of electricity= 9.86 ₹
- Per unit cost of DG, electricity=22.83 ₹
- (Note: we are considering 70% from electricity and 30% from DG for per unit cost)
- Total energy generated by solar per year (units) = 14,850 units or KWH
- Total savings per year (in rupees) = 1,84,868₹
- PAYBACK PERIOD
- Project cost: 8,60,165₹
- Payback period will be around year= 4.65 years
After SubsidyProject Cost will be ( IN Rupees)= 6,02,116
PAY BACK period will be around,Year = 3.26
- Hidden Savings:
- a) Night Sleep Mode: As mentioned above the night sleep mode has resulted in hidden savings which when calculated amount to savings of more than 10,000₹ per annum.
- b) Student’s Productivity: Frequent power cut causes loss in concentration of the students which cannot be measured in terms of money. All this is avoided by an un-interrupted supply.
- c) Cooled Terrace: The Sun rays falling directly on the terrace caused it to heat up and increase the temperature of the room below. The solar panels structure causes it to naturally bring down the temperature by providing shade.
- d) No more Diesel Pilferage: A lot of human effort to bring (transport costs) and store (storage space) the diesel whilst ensuring that theft does not occur (precious man-hours) was required earlier. Not anymore.
- e) Exporting to the grid through net metering: Once the State electricity board allows for Grid export then Holidays, lean load days and winter days will result in a faster payback period through the feature of grid export via net metering.
With Statcon Energiaa’s vast experience in the field of Solar Power Electronics, be sure to get an efficient system, saving not only your Money but Mother Earth as well.