How to calculate cost of installation of solar PV system

Design of standalone (off-grid ) Solar PV Panel with battery storage for one day of autonomy 

1. Calculation of the total load of electrical appliances in use and calculation of power consumption in one day.

Appliances	Rating	Quantity	Hour used per day	Watt Hour per day
Light bulb	3 watts	3	2	18
Light bulb	9 watts	4	5	180
Light bulb	10 watts	3	5	150
Light bulb	40 watts	1	1	40
Fan	75 watts	5	5	1875
Television	75 watts	1	6	450
Washing machine	500 watts	1	0.5	250
Refrigerator	300 watts	1	24	7200
Iron press	500 watts	1	0.5	250
Gyser	2000 watts	1	0.5	1000
Microwave oven	2000 watts	1	0.1	200
Mixer gringer	400 watts	1	0.5	200
Heater blower	1000 watts	1	1	1000
Exhaust	150 watts	1	1	150
Total	7415 watts			12963

2. Calculation of the number of solar PV panels required for power consumption.

First, we need the specifications of the PV module, Battery, and Inverter :

SPECIFICATIONS

SPECIFICATIONS
Solar PV Module	Rated Power	150 W
	Efficiency	75%
	Combined Efficiency	81%
Battery	Capacity	150 Ah
	Voltage	12 V
	Efficiency	80%
Inverter	Rating	Available in:
		100VA, 200VA, 1000 VA, 1500 VA, 2000 VA, 4000VA

Solar PV sizing

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑛𝑛𝑒𝑐𝑡𝑒𝑑 𝑙𝑜𝑎𝑑 𝑜𝑛 𝑃𝑉 𝑝𝑎𝑛𝑒𝑙 𝑠𝑦𝑠𝑡𝑒𝑚 = 𝑁𝑜. 𝑜𝑓 𝑢𝑛𝑖𝑡𝑠 ∗ 𝑟𝑎𝑡𝑖𝑛𝑔 𝑜𝑓 𝑒𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 = $7415$ watts

𝑇𝑜𝑡𝑎𝑙 𝑊ℎ 𝑟𝑎𝑡𝑖𝑛𝑔 = 𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑛𝑛𝑒𝑐𝑡𝑒𝑑 𝑙𝑜𝑎𝑑 ∗ 𝐻𝑜𝑢𝑟𝑠 $= 12963 𝑊ℎ$  

𝐴𝑐𝑡𝑢𝑎𝑙 𝑃𝑜𝑤𝑒𝑟 𝑂𝑢𝑡𝑝𝑢𝑡 𝑜𝑓 𝑃𝑉 𝑝𝑎𝑛𝑒𝑙 = 𝑝𝑒𝑎𝑘 𝑝𝑜𝑤𝑒𝑟 𝑟𝑎𝑡𝑖𝑛𝑔 ∗ 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝑓𝑎𝑐𝑡𝑜𝑟

 $= 150 𝑊 ∗ 0.75 = 112.5 𝑊$

 𝑇ℎ𝑒 𝑝𝑜𝑤𝑒𝑟 𝑢𝑠𝑒𝑑 𝑎𝑡 𝑡ℎ𝑒 𝑒𝑛𝑑 𝑢𝑠𝑒 = 𝑎𝑐𝑡𝑢𝑎𝑙 𝑝𝑜𝑤𝑒𝑟 ∗ 𝑐𝑜𝑚𝑏𝑖𝑛𝑒𝑑 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 

$= 112.5 ∗ 0.81 = 91.125 𝑊$  

𝐸𝑛𝑒𝑟𝑔𝑦 𝑝𝑟𝑜𝑑𝑢𝑐𝑒𝑑 𝑏𝑦 𝑜𝑛𝑒 150 𝑊 𝑝𝑎𝑛𝑒𝑙 𝑖𝑛 𝑎 𝑑𝑎𝑦 = 𝑝𝑜𝑤𝑒𝑟 𝑎𝑡 𝑒𝑛𝑑 𝑢𝑠𝑒 $∗ 10ℎ/𝑑𝑎𝑦 = 911.25 𝑊ℎ$

 𝑁𝑜. 𝑜𝑓 𝑃𝑉 𝑝𝑎𝑛𝑒𝑙𝑠 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 𝑇𝑜𝑡𝑎𝑙 𝑊ℎ 𝑟𝑎𝑡𝑖𝑛𝑔 𝑑𝑎𝑖𝑙𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 𝑝𝑟𝑜𝑑𝑢𝑐𝑒𝑑 𝑏𝑦 𝑎 𝑝𝑎𝑛𝑒𝑙

 $= \frac{12963}{911.25}$ $= 14.225 ≈ 15$

It is recommended to install 15 PV modules

3. Calculation of number of battery storage required for one day of autonomy

$Battery\:Capacity(Ah)=\frac{(\frac{Total\:Wh}{day} )\times{Days\:of\:autonomy}}{(battery\:combined\:efficency)\times(battery\:voltage)}\\\:\quad\:\quad\:\quad\:\quad\:\quad\:\quad=\frac{12963\times1}{0.8\times0.9\times12}=1500.34\:Ah\\Number\:of\:batteries\:required=\frac{Battery\:capacity}{Battery\:rating}=\frac{1500.34}{150}=10$

 It is recommended to install 10 numbers of 150 Ah batteries. 

Battery rating can be more or less.

4. Calculation the number of inverters. 

        Inverter sizing

$Inverter\:rating(W\:or\:VA)=Total\:connected\:load\:to\:PV\:panal\:system=7415\:W\\ No.\:of\:Inverters=\frac{Total\:connected\:load\:to\:PV\:panal}{Inverter rating}=\frac{7415}{4000}=1.853\thickapprox2$

It is recommended to install two 4000 VA rating inverters.

5. Calculation of total cost.

        Total Cost

$Cost\:of\:arrays=No.\:of\:PV\:module\times cost\:per\:module=15\times 6000=90000\\ Cost\:of\:batteries=No.\:of\:batteries\times cost\:per\:battery=10\times 15000=150000\\ Cost\:of\:Inverters=No.\:of\:inverters\times cost\:per\:inverter=2\times 18000=36000\\ Total\:cost\:of\:system=cost\:of\:arrays+cost\:of\:batteries+cost\:of\:inverters=90000+150000+36000=276000\\ 5\% \:additional\:cost\:of\:wiring=\frac{5}{100}\times 276000=13800\\ The\:final\:cost\:of\:the\:system=276000+13800=289800$

The total cost of the system is Rs 2,89,800.