PV Gap

Josephine Said:

Some electric billing questions?

We Answered:

what is the time needed for the 7400kWh household use. if it is a year, then the calculation will go like this.
a)
(7400kWh/year) / (365days/year) = 20.27 kWh/day
20.27 kWh/3.9kWh = 5.19 panels.
you will then need 6 panels. You will generate 8541kWh/year

b)
6 panels * $6000 = $36,000 to install the panels

c)
7400kWh x $ 0.18 = $1332 /yr saving
payback = 36000/1332 = 27 years.

Craig Said:

Maths problems please help?

We Answered:

Asuming the 7400kWh is per year:

a) 1 solar panel produces 3.9*365 kWh a year = 1423.5kWh

To work out number of panels needed 7400/1423.5 = 5.198 round up to 6 (normally you would round down but 5 panels would not produce the engergy needed).

b) $6000*6 = $36000

c) Work out total cost of electricity per year from grid: $0.18*7400 = $1332

Number of years = 36000/1332 = 27.02