EV charging site planner
A ballpark pro forma for a charging site: what it costs to build, what it costs to run, and how many sessions it needs before it stops losing money. The defaults are typical numbers. Swap in real quotes the moment you have them.
What the planner does
It builds a pro forma for one charging site: what it costs to build, what it costs to run, what it earns, and how busy each port has to be before the whole thing stops losing money. DC fast and Level 2 can share a site. Everything is in today's dollars, pre-tax and unlevered, so it answers "is this a good site" before anyone asks "how do I pay for it."
What goes in
- The chargers: how many, how big, what they cost, and how many sessions each port sees in year one.
- Construction: make-ready, any utility upgrade, design and permitting, and contingency. Grants and utility rebates come off the top.
- Electricity: the energy rate, the demand charge, and how much of the installed power actually shows up on the bill.
- Running costs: network software, maintenance, payment processing, host revenue share, lease and insurance.
- If you want them: a battery, the cost of failed sessions, and environmental credits.
What comes out
- Net project cost, operating profit, net present value, IRR and payback.
- Break-even sessions per port per day. This is the number to argue about.
- A share link, a spreadsheet and a one-page printout for whoever has to say yes.
What it assumes
- Billed demand is installed power times a percentage, every month, all year. At low utilization, one session can set the month's demand charge.
- Grid energy is delivered energy divided by charger efficiency. The losses are yours, not the driver's.
- Sessions grow at a flat rate, capped at 24 per port per day for DC and 8 for Level 2.
- No depreciation, no hardware replacement and no residual value. The formulas are written out on the method page.
Questions people ask
How many sessions a day does a DC fast charger need to break even?
It depends on your demand charge, your price and what the site cost to build, which is why the planner works it out for your site instead of quoting a rule of thumb. Fill in the inputs above and the results give you two numbers: the sessions per port per day that earn the capital back, and the lower number that just covers the monthly bills. Jump to your break-even.
Why do demand charges matter so much?
A demand charge bills your highest short burst of power in the month, per kW, no matter how many sessions you ran. A 150 kW charger that ran once can set the same charge as one that ran forty times. At a quiet site it is often the biggest line on the power bill. The business guide has the full story, including a one-session month that cost over two thousand dollars.
Should I use the defaults or real quotes?
Defaults to decide whether the site is worth a phone call. Real quotes before you sign anything. Get sessions per day and the demand charge right first, because those two decide the answer more than everything else combined.
Does a good NPV mean I should build it?
It means the math works if the inputs are right. The inputs are the hard part. Check the session estimate against the benchmarks and the utilization forecast, and walk the site before you believe any of it.