Question

I am so lost on all of this.

Here is the raw data /technical specifications for this new product needed to solve all parts of this question. Powerall modular Storage = 10 KWHs Continuous discharge power = 2KW Battery Technology = Li-Ion @ 100 watt hours per kg. Purchase + installation cost = $4000 Residential electricy rate = 0.1$ (10 cents) per KWH. Typical residential rooftop PV array rated at 4 KW maximum output (=noon on a sunny day) Average output in a day = 1/3 of peak Rooftop cost + installation = $1.80 per peak watt. Average number of suitably sunny days per year = 160:

a) What is the weight of the 10 KWH modular storage unit and how many hours does it take to discharge?

b) What are the up front costs to the homeowner for the purchase and installation of the storage unit and the PV rooftop?

c) Averaged over the year, what is average daily available solar energy that can be used to charge up the powerall system?

d) How many hours, given this average daily available solar power, would it take to fully charge the 10 KWH system

e) given your answer for d - explain what the homeowner would need to do to overcome this basic problem and estimate how much more this might cost.

f) given d+e and the residential electricity rate described above, what is the approximate pay back time for just one of these storage modules?

Answer 1

A) Given: modular storage =10kwhs = 10,000 Wh

Discharge power = 2 KW

Battery technology Li ion@ 100 Wh/kg.

Weight of the modular storage unit w = 10000wh/100wh/kg

w = 100 kg

Hours it take to discharge = 10000/2000 =5 hours

B) Up front costs :

Purchase + installation costs = $ 4000

Electricity rate is 0.1$ per kWh , for modular storage we have 1$ cost

Average output in a day = 1/3 × 4KW = 4/3 KW

In a year , its is 160×4/3 KW = 213.33 kW

Purchase + installation cost = $1.80 ×4 (peak in a day)

C) averaged over the year we are getting 231.33 kW output

d) daily average power output is 1.33 kw

It will take 10/1.33 = 7.51 hours approx 8 hours