I wen through the analysis of the best EVSE for a local community center in some detail recently.
I found that the dual 48 Amp EVSE's on a single pedestal to the best, most cost effective solution from
ClipperCreek: Dual HCS-60 with Pedestal
If you only want to serve Tesla's, the Tesla HPWC is a very cost effective option, and Clipper Creek now sells pedestals on which you can mount 1 or two HPWC's
If you are on a Commercial Electric Rate schedule, check on demand charges, they can be shocking. When I looked at the "all-in" total demand charges in Boulder, CO from Xcel Energy, the Demand Charges were over $20 per kW.
If they're on Nashville Electric Service, rate schedules are at
Nashville Electric Service .
As Cottonwood points out, your company will be paying both for the power and for the demand. In NES' rates I see demand charges of around $14/kW-$18/kW, depending on total power consumption.
PHEVs can only charge at 3.3kW. (Exception: 2016 Volt is now up to 3.6kW on a 240V supply.) 3.3kW charging allows for 7 to 14 miles per hour, depending on temperature, precipiation, wind, vehicle efficiency and use of climate control. Even at 7mph, an 8 hour day would add 56 miles. That's into stretch commuting territory. At that point I'd suggest that really you want to favor telecommuting over driving into the office.
Because non-fee EV chargers are relatively cheap, over time demand charges could end up dwarfing the initial cost. ($46.2/mo for each additional 3.3kW charging at $14/kW; for comparison, if you pay $0.13/kWh and fully charged a Volt at 3.3kW 20 days per month, the cost of the kWh used would be less than that!) So, I'd see if you can easily see how your electricity demand varies during the day. It might be that you could provide some charging in the morning without incurring additional demand charges. At 3.3kW, shorter-range PHEV like the Prius Plug-in or Ford Energis would be fully charged in under 2.5 hours, a Gen 1 Volt in about 4 hours and a Gen 2 in 4.5 to 5 hours. Then beyond using "spare" power, to minimize demand charges you want to favor consecutive over simultaneous charging. So in a cost-effective set-up:
- some chargers would only be available during periods of low-demand; you would have PHEV drivers plug into those in the morning.
- some chargers would be available all day and have a cooperative charging system where owners unplug and move their car.
If people think that's penny-pinching, just consider that saving $46.20/mo means $554.40/year that can be diverted into other benefits.
So, if I'm thinking ahead, to having more people with plugin cars, I'd be asking the landlord to have the building wired so that you can easily hook up a bunch of 240V/16A chargers as needed (if you have the EV parking by a wall, Clipper Creek LCS-20 is outdoor rated and $379 each), along with an easy ability to control when they're powered on (which you want so you don't worry about Nissan Leaf owners stealing electricity at weekends

). For the near term, I think that would maximize the benefit of benefit dollars. I think that longer term, more people will have long-range electric cars, so there won't be a financial benefit to charging at work and then you can put more of the money into hardware and software that makes telecommuting better.