How to avoid an eye watering energy bill – an EV case study
By Robert Waldie Energy Solution Architect
This is a cautionary tale of a single ill-timed charge session that pushed my EV’s energy cost per kilometre well beyond the worst internal combustion engine gas guzzler. Like, four times worse than an old-school Hummer H1.
At home I charge my EV from rooftop solar and, outside daylight hours, a home battery. My system is sized such that most days I barely touch the grid, which satisfies my inner sustainability nerd and delights my inner cheapskate. However, one cloudy late afternoon, not realising my home battery was flat, I absent-mindedly plugged in – triggering an 11kW spike in grid power and adding more than $60 to my monthly power bill.
This is because I’m on a demand tariff. In addition to paying for the energy I use, I’m also billed on my maximum load during the peak evening period. The fact I had negligible load during the evening ‘demand window’ all month didn’t matter. I was penalised as if I’d drawn that much grid power every night. And during that 30-minute charge I added only around 30 km of range, effectively paying $2 per kilometre for energy. In internal combustion energy terms, that’s like paying $25 per litre for petrol.
An extra $60 demand charge on a residential bill is an annoyance. But for a commercial EV charge point operator, an unexpected demand charge can completely blow up the business case.
Depot EV chargers
Under commercial tariffs, the stakes are far higher – demand rates are three to five times that of residential. Pair that with EV fast charge stations capable of 150kW+, and a single spike can add thousands of dollars to that month’s bill. And unlike at home, where I can avoid charging in the evening by scheduling a blockout period, public sites can’t control when customers charge. In fact, the demand window lines up perfectly with the evening commuter rush.
That’s why for clean energy tech firm SwitchDin’s customers, managing demand charges through site battery and EV charger orchestration is typically the first optimisation strategy we recommend.
And often that first step is the one that proves the most effective at reducing energy costs. With smart load profiling and tariff-aware operation, SwitchDin is able to keep EV fast charging predictable and always available. No bill shocks and no disappointingly slow sessions. And the result – drivers stay happy and margins stay healthy.
The lesson: To avoid an eye watering energy bill, manage your peak power draw using available optimisation and orchestration services.
