Load Survey based Solarification Project for a Remote Village

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Load Survey based Solarification Project for a Remote Village

1Ramesh Chander Bansal, 2 Dr. Mohammad Muazzam , 3 Dr. Alok Kumar Bharadwaj

1Ph.D scholar, 3 Professor

1, 2, 3 Electrical Engineering Department, Mewar University, Rajasthan, India.

Abstract:- As compared to Renewable Energy Sources (RES) like biomass and wind, the concept of generating and utilizing power in a more distributed way and at flexible scales suites best with Photovoltaic (PV) technology. The PV panel concept is truly distributed with common (public) as well as private ownership and environmentally it is best suited with lower scale of investment and just as per decided size of PV system. For wind, observations like huge Wind Turbine (WT) investment, land availability at appropriate location, a wiring network to consumer houses and future maintenance seems to be major issues. Wind farm is more feasible for an agency who can invest and take its benefit but still there is uncertainty of customer users on a long way. Solar energy integration at village level requires proper planning that spans across social, government policy, technical and economic dimensions. Initiating such a planning process in a participatory way and designing integrated PV solutions for different categories of consumers in a large but distributed scale is quite a challenging task. In this paper, a case of village Solarification considering load study and PV system adoption matching tech-economic needs of various categories of community, is submitted.

INTRODUCTION

Solarification is a concept in which a village supported by committee of villagers; moves towards energy security by meeting most of its daily energy needs in terms of electricity by distributed solar PV solutions[2]. The concept does not mean 100% of the electricity demand is met by solar PV. There should be an optimum level of offsetting grid load [1] with solar by integrating custom made solutions to different category of consumers. These custom solutions can be in terms of selected technology, based on demands, load patterns, time spread and classification of loads, reliability with back up of supply and appropriate financing models. Finally, the operation and maintenance of the distributed power generation systems will also be undertaken by a local co-operative body itself, which can then generate a pool of local jobs. The institutional or social enterprise (business) model has to be carefully designed. Individual houses may be equipped with PV panels and inverters [3] with net metering concept especially where roof top PV installation is feasible. Following standards [11] for safety of equipments and personnel is a basic step in project implementation

The aim of this study is to create a proper design methodology and implementation strategy to add a village Solarification through innovations in technology design,

planning, implementation, and post implementation management. This needs technical know-how, micro level strategic planning and capacity building for implementation, operation and maintenance. Following objectives may be submitted:

  1. Current load data collection and analyzing them to decide planning strategy of solar equipments.

  2. To identify the existing solar PV technologies with or without wind power matching [4] and solutions which can be implemented to meet the regular load patterns of existing customers in a village

  3. To identify, analyze and develop appropriate PV solutions [9-10] for rural areas for easy integration to the existing grid or an off grid.

  4. To study the designs and implementation challenges of a de-centralized solar PV power project [5] at a village level and to come up with an appropriate planning and execution strategy at comparatively lower cost [12].

  5. To document the learnings from this project in terms of conducting a load survey, technology solutions, and implementation strategy for larger understanding and replication of such projects in other places of the state and the country.

REFERENCES

The paper includes organization covering section II for action plan, RES survey at site, data cleaning and data analysis. Considering load demand analysis, the section III covers proposed inverter sizes as per load category. The section IV proposes the design packages of PV modules along with inverters for five categories of consumers from lowest slab to most upper slab consumer. The section V covers an energy case study example of grid connected roof top PV system [6,7 and 8] without feed in tariff in a school located in the village. At last conclusion is presented with foreseen limitations.

SECTION II

PROPOSED ACTION PLAN FOR VILLAGE SOLARIFICATION

Figure 1 shows the action plan for total project activities starting from goal planning to execution including technology decision and villagers category wise techno- economic solution.

Figure 1 Action Plan of the proposed project at a village near Kukas Jaipur

Energy Survey at Site

Although the detailed information about power consumption was available from secondary data (RSEB Energy bills), a 100% survey of households for each category of consumers is conducted. Planning for roof-top PV installations at village level is also included. A questionnaire survey was planned with following key objectives of the Survey:

  • To collect the power consumption and load data of all the houses, schools and offices in the village.

  • To identify the approximate shade-free roof-top area in different buildings in the village.

  • General details of the buildings ownership, use, type of construction etc.

  • Data from utility bills such as kWh consumed, connected load, bill amount (for past 3 bills).

  • Load consumption pattern of households and

commercial establishments (approximate load and duration of usage of different appliances).

A used questionnaire for households survey is added in figure 2. For surveying the public buildings, the above mentioned questionnaire is modified with questions pertaining to average working days and a detailed table for used equipments.

Model Questionnaire for solar PV Requirement of the village and School Date———

Ward no.

House No.

Owners name

Consumer Bill no.

Address

Mobile

Is electricity available

Yes No

Tariff

Single Phase

Three Phase

Connection Load

Average Monthly Consumption

Units

Amount

Alternate source of Electricity

Yes

No

DG set Monthly Expenses

LPG Lamp Monthly Expenses

Owners signature

Figure 2 showing load survey questioner

Data Entry and Cleaning

Several errors were found in the data so collected. To improve the accuracy of data, cleaning was done by data correction, deletion, and matching the figures with cross checking before analysis. Following steps were helpful in data cleaning:.

  1. Manual correction of forms, from the secondary data available online by entering consumers bill number.

  2. 35 cases on sampling basis were cross-checked with online bill data by entering the consumer number which was in the questionnaire form.

  3. Limits for each field were also used at the next stage for data correction. For domestic users, the counts of certain equipment were rounded off to an upper limit in some cases. e.g. if the response in a questionnaire states that there are more than 2 television sets in a house or there

are more than 10 incandescent lamps/ fans etc., the counts were limited to a maximum number (2 for T.V, 10 for incandescent lamps, fans and other lighting sources). Similarly the lower limit for connected load was set as 20

W. After all these filtering and validation procedures, 100% entries were available for detailed analysis on which the data analysis was carried out. In the following discussions all percentages are with reference to these 143 entries unless otherwise stated.

Data Analysis of Survey data

Nearly 100% consumer base has been covered in the survey. A good percentage of the survey data (Average: 67%) has been taken for analysis after data cleaning from all wards. Table 1 shows the category and number of houses/office buildings that were covered during the survey.

Table 1 Building classification of Consumers

Category

Number

House

143

Shops

5

School

2

Hospital

0

Official Building

0

Bank

0

Community Hall

1

Temple/Dharmashala

1

Data Analysis and Discussions

Analysis of data should be done separately for households and public buildings but in our case there is no public building. Demand of the consumer and their roof- top potential are the key parameters used for this analysis.

Demand Analysis

Demand analysis looks basically into the load and energy demand of the consumers including primary and secondary data sources. The classification of households under various ranges of connected loads is done to understand the distribution of household loads under various connected load categories as shown in figure 3.

Connected Load range in the village

8% 4% 2% 12%

Connected Load range in the village

8% 4% 2% 12%

12%

14%

22% 26%

12%

14%

22% 26%

0-50

50-150

150-500

500-1000

1000-1500

0-50

50-150

150-500

500-1000

1000-1500

Figure 3 showing Load distribution of the surveyed Village

Figure 3, shows that majority of the domestic consumers (74%) have their connected load less than 1000 W (between 50 – 1000 W) and 86% under 1500 W connected load. This indicates that majority of the households are using electrical appliances of comparatively low power ratings. This also gives an indication that most of the households in the village are using only those appliances to meet their basic needs (like lights, fan and TV). Following observations are recorded:

  • 94% of the consumers are covered in tariff range between 0 to 400 kWh (bimonthly)

  • 12% of households consume between 0 – 80 kWh and 52% between 0 150 kWh

  • And 14% houses in the village are consuming more than 300 kWh per month.

  • The energy usage pattern of the village is majorly governed by a large number of consumers (66%) who are using 80 to 300 kWh monthly.

    Further, figure 4 shows that there is a steady increase in the ownership of water pumps and washing machines if we move from the lower slabs to the higher slabs. They become very common equipment used in the households at the higher consumption slabs.

    %

    V

    a i a t i o n

    120

    100

    80

    60

    40

    20

    0

    Equipment Load variation as per slab

    Water Pump PC

    washing m/c water Cooler Water Heater

    A/C

    %

    V

    a i a t i o n

    120

    100

    80

    60

    40

    20

    0

    Equipment Load variation as per slab

    Water Pump PC

    washing m/c water Cooler Water Heater

    A/C

    Load Slab

    Load Slab

    Figure 4 showing slab wise additional connected load equipments

    For study of equipment usage Pattern of Domestic Consumers considering time based electricity usage pattern of both critical and normal load, the entire day is split into 4 time slots of variable duration for analysis Slot1( 6 PM to 10 PM having 4 hours peak hours), Slot 2 (10 PM to

    7AM with 9 hours off peak hours), Slot 3(7 AM to 12 noon with 5 hours as normal period), and Slot 4(12 noon to 6 PM with 6 hours as normal period).The connected load consumption for lower, middle and upper middle class of consumers are shown in respective following figures 5-6.

    6PM-10PM

    10PM-7AM

    7AM-12PM

    12PM-6PM

    FAN

    34.5

    20

    12

    25

    CFL

    6.9

    1.2

    2.2

    12

    INC LAMP

    15

    0

    0

    0

    FT

    23

    0

    8

    0

    TV

    84

    0

    0

    20

    6PM-10PM

    10PM-7AM

    7AM-12PM

    12PM-6PM

    FAN

    34.5

    20

    12

    25

    CFL

    6.9

    1.2

    2.2

    12

    INC LAMP

    15

    0

    0

    0

    FT

    23

    0

    8

    0

    TV

    84

    0

    0

    20

    180

    lOAD (WATT)

    lOAD (WATT)

    160

    140

    120

    100

    80

    60

    40

    20

    0

    Critical Load cycle for lowest consumer

    Figure 5 showing critical load share for lower load category

    The figures 5-6, show that even if the equipments used are same, the number of equipments in use and duration of use varies. Additional equipments like refrigerator and washing machine also account for

    significant power consumption in the load curves of 150 – 500 kWh. TV consumes more or less constant amount of power in all categories. The power consumed by lighting sources varies from category to category.

    Critical Load cycle for Middle consumer

    lOAD (WATT)

    lOAD (WATT)

    300

    250

    200

    150

    100

    50

    0

    7AM

    12PM

    FAN

    90

    40

    24

    40

    CFL

    16.5

    2.4

    4.4

    0

    INC LAMP

    15

    0

    0

    0

    FT

    30

    0

    16

    0

    TV

    90

    13.3

    0

    30

    7AM

    12PM

    FAN

    90

    40

    24

    40

    CFL

    16.5

    2.4

    4.4

    0

    INC LAMP

    15

    0

    0

    0

    FT

    30

    0

    16

    0

    TV

    90

    13.3

    0

    30

    6PM-10PM

    10PM-

    7AM-

    12PM-6PM

    During slot 3 and slot 4, i.e. from 7 AM to 6 PM, the electricity demand from different categories of consumers can be analyzed from the above load curves. One of the options for meeting this energy requirement can be through implementation of grid interactive rooftop PV systems,

    without any battery backup. Considering higher value of the load under these two slots, as shown in table 3, one can determine the minimum size of the PV modules supporting these loads.

    Table 3 Proposed optimum roof top PV size for partial meeting the day time loads

    Load Slab (watt)

    Minimum PV capacity with back up from grid

    0-50

    50

    50-150

    70

    150-300

    140

    300-500

    250

    SECTION III USAGE OF INVERTERS IN THE VILLAGE

    The use of inverters in the village as per different load slabs, is analyzed in this section and proposed inverter sizes are proposed in table 4.

    Table 4 Proposed Inverter sizes as per consumer Load requirement

    Consumer Load Slab

    watt

    Consumer Population

    %

    Number of Houses

    Inverter Rating (VA)

    Capacity (VA)

    Minimum

    Maximum

    Minimum

    Maximum

    0-50

    12

    17

    250

    3000

    50-150

    14

    20

    250

    500

    3500

    10000

    150-500

    26

    36

    500

    800

    13000

    28800

    500-1000

    22

    32

    800

    1500

    17600

    48000

    1000-1500

    12

    17

    1500

    2000

    25500

    34000

    1500-2000

    8

    12

    3000

    4000

    36000

    48000

    2000-2500

    4

    6

    3000

    4000

    18000

    24000

    2500-3000

    2

    3

    4000

    5000

    12000

    15000

    Total

    100%

    143

    _

    _

    128600

    207800

    Table 4 shows that inverter size and range varies as we go from lower to higher slab because when load variety and ratings are larger their operation time and consumption too varies widely. Roof top investment into such systems varies from Rs 2000 to Rs 24000. It is interesting to note that among the people who use consuming above 300 kWh of electricity bimonthly, around 33 % own power backup systems.

    Based on PVSyst simulation software package (for study, sizing and designing PV systems) and NASA satellite based Surface Solar Energy (NASA SSE) meteorological data; shows that using minimum 13%

    efficient panels in proposed village application, the area required per kW is 118 sq. ft. If 15% efficient panels are used then area required is 78 sq. ft. per kW. Efficiencies of commercial crystalline silicon modules, which are a leading technology for rooftop installations, vary from 13- 20%. Assuming an inter-panel spacing of 25% of the active area, the typical area required for installation of solar panels in the efficiency range from 13-16% will be maximum 150 sq. ft. per kW. Based on these, guidelines, the roof-top potential of domestic consumers is classified from 1kW to 5kW PV capacity to meet their load demands.

    PVSyst data shows that a solar PV installation of 1 kW in the village would give about 4.5 kWh yield per day. By adding up, all the average installations, the harvested power works out 121.5 kWh at 0.6 power factor and requiring 15,150 sq. ft. area for installing PV modules. The area may be an open non fertile area identified by Panchayat or roof top area in part.

    SECTION IV DESIGN PACKAGES FOR DOMESTIC CONSUMERS OF THE VILLAGE

    Based on primary survey information, a design approach for different slabs of domestic consumers, based on the critical load curves (Figure 4) and on possible use of the equipment in their custody are .proposed with following assumptions as ready to use condition.

  • The number and types of loads required for a class of consumer is decided as per the.

  • The sizing of PV modules is based on their average daily consumption from grid, i.e. based on the tariff slab they belong to.

  • Further, the major assumption is that 50% of the daily energy consumption is offset by PV packages, i.e. a consumer who uses to 30 kWh per month must offset at least 0.5 kWh daily using PV.

  • Battery bank designed is slightly undersized in some packages based on the assumption that some part of

    the PV energy produced (in the 50% grid offset energy) is directly utilized during day time (using grid tied inverters). Hence decreasing the need for storage and avoids some efficiency losses.

  • The prices are indicative and based on the primary data collected from open market.

  • It is mandatory for all manufacturers offer a guarantee of performance over a period of 25 years with 90% output for first 12 years and up to 80% after 25 years of operation. It has to be kept in mind that there is a degradation of about 0.9% per year in PV module output while designing the packages.

    The packages are designed by using different standard module sizes and batteries. This set of packages is one set of example for each category of consumers. Further these may be optimized based on the actual expected daily energy need, monthly energy consumption, number of kWh to be saved to jump down to the next lower consumption slab to avail additional benefit of lower tariff. There are three slabs of consumers and accordingly three set of solar packs are designed and shown in table 5 for lowest slab, as per table 6 for middle slab consumers and as per table 7 for upper middle consumers while table 8 for upper most slab of consumers.

    Table 5 Lowest slab consumer solar pack

    Slab

    Equipment in use

    Proposed Solar Pack

    Other Spec.

    Cost(INR)

    Equipment

    Qty

    Power

    Equipment

    Qty

    Spec.

    0-80 w

    Fan

    1

    40-60 w

    PV module

    100 w

    Mono/Multi crystalline

    10 years product warranty and 25 years performance warranty

    6000

    TV

    1

    80-

    120W

    Inverter/ Power Conditioning Unit

    300 VA

    Minimum Efficiency of 90%, Pure Sine wave

    Automatic load management system

    5000

    Fluorescent light (4 ft)

    1

    40w

    Battery Bank

    100Ah,

    12V (1200 wh)

    Tubular GEL VRLA

    12000

    CFL

    2

    12w

    Other BOS and installation Charges

    3000

    Total

    26000

    Table 6 Mid-slab consumer solar pack

    Slab

    Equipment in use

    Proposed Solar Pack

    Other Spec.

    Cost(INR)

    Equipment

    Qty

    Power

    Equipment

    Qty

    Spec.

    50-

    150

    w

    Fan

    1

    40-60 w

    PV module

    200 w

    Mono/Multi crystalline

    10 years product

    warranty and 25 years performance warranty

    12000

    TV

    1

    80-

    120W

    Inverter/ Power Conditioning Unit

    500 VA

    Minimum Efficiency of

    90%, Pure Sinewave

    Automatic load management system

    5000

    Fluorescent light (4 ft)

    1

    40w

    Battery Bank

    100Ah,

    12V (1200

    Wh)

    Tubular GEL VRLA

    12000

    CFL

    3

    12w

    Other BOS and installation Charges

    8000

    Total

    37000

    Table 7 Upper Middle- slab consumer solar pack

    Slab

    Equipment in use

    Proposed Solar Pack

    Other Spec.

    Cost(INR)

    Equipment

    Qty

    Power

    Equipment

    Qty

    Spec.

    160-

    240 w

    Fan

    3

    40-60

    w

    PV module

    500 w

    Mono/Multi crystalline

    10 years

    product warranty and

    25 years

    performance warrranty

    30,000

    TV

    1

    80-

    120W

    Inverter/ Power Conditioning Unit

    1200 VA

    Minimum Efficiency of 90%, Pure Sinewave

    Automatic load management system

    10,000

    Fluorescent light (4 ft)

    1

    40w

    Battery Bank

    150Ah,

    12V,2nos (3600 Wh)

    Tubular GEL VRLA

    32000

    CFL

    3

    12w

    Other BOS and installation Charges

    22,000

    Fridge, washing m/c Water pump

    200-

    300W

    Total

    94,000

    Table 8 Upper Most – slab consumer solar pack

    Slab

    Equipment in use

    Proposed Solar Pack

    Other Spec.

    Cost(INR)

    Equipment

    Qty

    Power

    Equipment

    Qty

    Spec.

    250-

    500w

    Fan

    3

    40-60

    w

    PV module

    1000 w

    Mono/Multi crystalline

    10 years

    product warranty and

    25 years

    performance warrranty

    60,000

    TV

    1

    80-

    120W

    Inverter/ Power Conditioning Unit

    1500 VA

    Minimum Efficiency of 90%, Pure Sinewave

    Automatic load management system

    15,000

    Fluorescent light (4 ft)

    1

    40w

    Battery Bank

    150Ah,

    12V,4nos (7200 Wh)

    Tubular GEL VRLA

    64000

    CFL

    3

    12w

    Other BOS and installation Charges

    40,000

    Fridge, washing m/c Water pump

    200-

    300W

    Refrigerator*

    Washing Machine*

    Mixer*

    Water Pump (0.5 HP)*

    1

    1

    1

    200-

    300W

    500-

    700W

    200-

    300W

    373W

    Total

    1,79,000

    SECTION V

    CASE STUDY: INSTALLATION OF GRID CONNECTED ROOFTOP POWER PLANTS IN SCHOOLS

    In this case following assumptions are made (1) RSEB has approved 17 kW PV roof top installation for grid connectivity. (2) RSEB will not exempt the PV system owners from their fixed charges since they provide them a reliable back up option, but there will be incentive for feeding excess energy into the grid. (3) We shall take Rs 5/kWh as feed in tariff (nearly same as current cost for RSEB). (4) This will ensure that the system owners can utilize the entire rooftop potential and sell power to the

    grid. (5) Some part of their bi-monthly consumption may be still drawn from the grid, during non sunshine hours (rainy days, shading by clouds etc.). But since net metering is used, these kWh will be deducted from the total generated energy. In other words it may be said:

  • Net energy fed into the grid = (Net energy produced by PV self consumption)

  • Total income to the rooftop system owner = 100% energy charges +energy duty + feed in tariff for remaining energy produced.

The cost data and savings based on following steps are summarized in table 10.

Energy generated (bimonthly) = 17 kWp *3.75 kWh/kWp/day*60 day = 3825 kWh

Energy consumed (self use) 366 kWh

Energy fed into the grid = (3825-366) = 3459 kWh

Income on feed in tariff = 3459 * 5 = Rs 17,295

Total benefit to the rooftop owner in 2 months = 17295 + 2053 (energy charge) = Rs 19,348

Simple payback period = (8, 50,000)/ (19348*6) = 7.3 years

Table 10 when a Roof top system is grid connected at a school

Bimonthly saving (from bills) (Rs)

Item Head

Data/Calculated values

Size of PV system (Utilising full rooftop potential) (Wp)

17KW

Investment on PV (Rs 50/Wp – MNRE bench mark price) (Rs)

8,50,000

Net energy fed to the grid (bimonthly) (kWh)

3459

2,053

Total Income (bimonthly) (Rs)

19,348

Simple payback period (years)

7.3

An important learning from the above calculation is that, the return of investment is more determined by the feed in tariffs, rather than by the savings from energy bills. The school may not be ready to invest such a huge capital on rooftop PV systems. This throws an opportunity for third party investors to step in and install rooftop PV system on school rooftops. The schools can demand for free power or a fixed lease amount per kWh produced.

CONCLUSION:

In the exercise of Solarification the load survey and site study including roof part and small buildings like school, shop, hospital or small scale industries etc. along with involvement of villagers at various capacities is the foundation of Solarification. The design and sizing of PV modules with corresponding inverters and back up batteries based on surveyed load data is second important aspect. The various five packages have been suggested covering minimum to upper slab of consumers. Additionally a case study of school building with roof top grid tied PV system exercise has been added to cover up total Solarification range from a small home needs to fully fledged grid connected PV system.

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