clarifying questions:

1. Are we focusing on individually owned EV charging or commercial or public charging stations? – Anywhere you can charge a EV car
2. Are these privately owned EV charging stations in a household in the US
3. and publicly available charging stations such as at work, malls etc. Is that correct? – Yes.

• Formula: Total US household EV chargers  + total public EV chargers  = total charging stations in the US.
• Total household EVC  = households that own solar+ households that don’t own solar(1M)
• Total public EV charger  = chargers at the rental apartment(included in the 1M above) + chargers at the workplace
• Total US population 300M, 100M households 80% own a car, 5% is EV.
• Total 4M EVs
• Avg 4% of households own solar
  • Total households in the US that own a solar= total household 100M * 0.04%= 2.5M households
• Total households in the US that own an EV charger= 50% of total solar owners = 2.5M* 0.5% = 1.25M
• total 4M EVs exists, 1.25M owners charge it at home using solar, let’s assume rest charge them using electricity, or EVs at rental apt = 2.75M * .04%= 1M EVs
• 10M employers in the US, 1% of them offer EV charging stations, 100K EV charging stations. assuming there are avg 5 charging stations per employer = 500K EVC

I’ll first start with some clarifications. (*EV = electric vehicles)

a. Do we want to estimate the number stations with exclusive EV charging bunks or hybrid stations as well. (lets assume for now, interviewer asks us to go with exclusive EV charging stations only).
b. I’d like to align on electric vehicles in general. So electric vehicles run on rechargeable elctric batteries which once charged generally run for 8hrs straight or 500 miles. Does this seem reasonable? (lets say interviewer say all good)

I’ll take a top down approach. Lets consider US is spread across ~4M Sq, miles.

Next lets divide the US total area into 3 buckets and assume that the charging stations will be proportional to EV usage:

a. States with high EV usage: like CA, NY, WA, NV etc.. Lets say 30% of US has high EV usage, so these states will likely have more EV charging stations.

b. States with no EV usage: like ND,SD, WY, TN etc.. Lets say 40% of US has no electric vehicles and hence no EV charging stations are established yet.

c. States with low to medium EV usage: like OH, TX, IL, GA, FL, WY etc.. Lets say remaining 30% of US has average EV usage, so lets assume the charging stations will be proportional to EV usage.

Further, lets divide the area into urban (downtown, tech areas, city centres) and rural(suburbs and country side).

i. In states with high EV usage, its likely that city limits have expanded due to growing prospects of living conditons, employments, salary etc(like bay area, san jose etc.). So lets assume of the total area, urban is 50% and rural is 50%. As the EV usage is high, lets say there is 1 EV charging station per 50 sq miles in urban while  1 EV charging station per 250 sq miles in rural.

ii. In states with low to medium EV usage, lets assume of the total area, urban is 30% and rural is 70%. In this case, as the EV usage is average and cold vary across states, lets say there is 1 EV charging station per 100 sq miles in urban and in rural areas.

Now lets calculate: (per discussion above 60% of US total area has EV usage and hence EV charging stations exist. We have assumed that states without usage of EVs have no charging stations.)

(High EV usage Urban) + (High EV usage Rural) +

(Average EV usage Urban) + (Average EV usage Rural) +

{30%*4M*50%*(1/50)} + {30%*4M*50%*(1/250)} + {30%*4M*30%*(1/100)} + {30%*4M*70%*(1/100)}

= {1.2M/100} + {1.2M/500} + {1.2M*(3/1000)} + {1.2M*(7/1000}

= 12000 + 2400 + 3600 + 8400 = 26,400 EV charging stations

We previously assumed that states without high EV usage do not have EV charging stations at all.. But in reality population with EVs could travel to states without high EV usage. And although not all of the states could have EV charging stations established, some popular tourist destinations, Inter-state highways etc. could have them. So we could add ~600 to the total number and say that there are approximately 27,000 EV charging stations in USA. Which sounds reasonable.

Hybrid stations:

Initially, we did not consider hybrid stations which are generally gas stations with 1 or 2 EV charging points in addition. If we need to add this to our estimate, we can do the following calculation. Lets say there is 1 gas station every 5 sq. miles across US.

Hybrids may not be common in states without EV usage, so we can minus 40% of the US total area from this calculation. Similarly states with low to medium usage might also have exclusive stations (gas or EV). We can exclude the other 30% as well.

We can expect hybrid stations in urban and rural areas in the states with high EV usage. Urban, so as to provide convenience to users and expand business and in some rural areas it’ll make sense to have a hybrid gas stations instead of having EV charging exclusively.  Urban has exclusive stations too, so lets say 2% of the traditional gas stations have hybrid stations and 3% of the rural areas have hybrid stations. We have considered urban and rural area % to be equal in states with high EVs. So to add the Hybrid stations we will do the below calculation:

{1.2M*50%*(1/5)*(2%)} + {1.2M*50%*(1/5)*(3%)} = 6000 hybrid stations

Including Hybrid stations, we will have a total of 33K EV charging stations. Seems quite reasonable!

Clarifying Questions ->

• Does this mean any specific type of chargers where chargers are segmented by
  • Fast chargers (mostly used in public or commercial)
  • Slow chargers (mostly used in private charging or semi private like office charging, sometimes even commercial fleet operations)
  • Battery Swapping operations
• Chargers are also segmented by
  • Public chargers (provided by Charging Networks – Tesla, ChargePoint, etc, provided in Hotels / Malls, part of gas station, on highways)
  • Semi – Private (e.g. office charging, apartments charging, mall charging, hotel charging / overlaps with Charging Network providers)
  • Private Chargers (primarily used by a house, or captive fleets)
• Charging is usually done for
  • commercial vehicles – city buses, small sized trucks, scooters, e-bikes for delivery, etc.) and  NOTE: electric long haul buses and trucks do not exist at the moment
  • passenger vehicles (mostly cars in US, e-bikes, e-skateboards, and other formats of personal mobility)

• WE WILL ASSUME FOR THIS EXERCISE THAT THIS INCLUDES ALL KINDS OF CHARGERS EXCEPT BATTERY SWAPPING WHICH IS LOW USAGE IN US
• It will be fair to show that majority of numbers will come from passenger vehicles and so it might be fair to ignore chargers used for commercial operations like fleet operators, will have to see how big is private charging networks

• To estimte the number of private chargers, we will estimate the number of electric cars and e-bikes and assume all of them have at least one charger at home
• We will assume that the population of US is X, there are 2-4 member families and each family has a car, so we will assume that on average there are 3 members in a family and so X/3 cars
• Next we will assume that there is y% of adoption of electric cars and then the number of cars and private / slow chargers will be y%of x/3
• Taking x as 300M and y as 5%, we get 5M electric cars / private slow chargers for electric cars
• We will assume that since US is an aging population, about 20% of people are in the age group of 15-25 who for their personal mobility needs use e-bikes, e-skateboards, etc
• The adoption of e-bikes, e-skateboards, etc is about 10% and each e-bike or e-skateboard comes with a private charger much smaller than electric car charger and so even if a family has an electric car and an electric bike, they use different chargers for them, and so using above number and say 75M young people with 10% adoption will be about 7.5M e-bike chargers
• Total Private chargers – 4M + 7.5M = 11.5M

• Charging Network Operators : Here we assume that
  • there are about 10 national charging point operators who each have about 10000 chargers
  • there are about 50 smaller or local operators and  each has about 500 charging stations
  • So total of about 100000 + 25000 = 0.125M
• Hotels and Malls :
  • Here we assume that there are 10 big cities, 50 mid sized cities, and 1000 small towns or cities in US
  • Big Cities have 100 hotels and malls, Mid sized cities have 25 hotels and malls and Small Cities and Towns have 5 hotels and malls
  • Each hotel or mall has about 5 chargers so in total it will be 10x100x5 (big cities) + 50x25x5 (Mid Sized) + 1000x5x5 (small cities) = 5000 + 6250 + 25000 = 36250 chargers – mostly fast chargers
• Private Fleet oeprators
  • Private fleet oeprators include citi bus operators, electric taxi operators, electric delivery fleet operators either by small trucks or on e-bikes, or rent a bike service
  • Most of them would exist in big and mid sized cities at the moment
  • We will asssume all big cities have similar adoption and about 30% mid cities have similar adoption
  • Electric Taxi operators –
    • National level – 10 players with an avergae of 500 cars with 1 charger shared between 3 cars given charging time of 6-8 hours and optimum utilization – so total of 1300 – 1400 chargers
    • Local Players – 25 cities x 10 operators per city x 50 cars per operator = 12500 cars, so 12500/3 = 4167 chargers
  • Bus Operators similarly could be 100 bus for national operators and 10-20 buses for local operators and even if we have 1 charger each given size of battery and rigidity to the time of operation this would be about 1300 chargers
  • E-bike rentals would be a larger number but still insignificant as compared to passenger vehicles
• So roughly commercial chargers are 0.125 M (Charge Operators) + 36250 (Hotel/Malls) + 5000 (Captive Fleet Chargers) [could be significantly higher for e-bikes fleets but not in order of passenger chargers] < 0.2M chargers < 0.5M chargers (even with huge assumption errors)