SunbeltSailor

Running my commute math in Phoenix: 28 miles round trip, 5 days, 48 weeks. At $4.50/gallon and 28 MPG that's about $1,350/year in fuel. Same miles in my Bolt at $0.10/kWh off-peak TOU is $168. The payback arithmetic on the purchase price has never looked better than it does right now. I understand the macro crisis is real. It just happens to be excellent for the numbers I actually run.

The Arizona version of this math works even cleaner. 5.8 PSH annual average, and July through September runs close to 7.0. My Bolt's daily consumption is covered by roughly 11 of my 14kW array before noon in summer. The EV didn't change my electricity bill — it just changed where the surplus goes.

One variable that shifts the comparison in Phoenix: both packs run hotter in 115°F ambient than the thermal specs suggest. The Ioniq 5's larger pack distributes the load across more cells under sustained high-temp charging. Small edge on paper, but in a climate where charging at 2pm in August is sometimes unavoidable, it's the kind of margin that compounds over five years.

I already filed my 2025 taxes without an extension. Installed a 13.5kWh DIY LFP pack in November 2025 — materials cost around $1,900. The 30% credit on $1,900 is $570. Is a 1040-X amendment worth it for $570? Genuinely asking — amended returns seem to invite extra scrutiny and I'm not sure the math works once I factor in CPA time.

The weight argument matters to me because I'm planning a 4WD truck camper build eventually. My 14kW home solar feeds the house fine but I need serious onboard storage for the camper. A 35% weight reduction in the pack would be meaningful in a vehicle application. But at $180–220/kWh for semi-solid versus $42–55 for LFP, the math doesn't pencil until you're genuinely weight-constrained — which a truck camper might actually be.

In Phoenix the ROI math is different from the article's baseline. APS peak pricing hits $0.28/kWh from 4–9pm in summer, so the storage arbitrage case is much stronger than a flat-rate market. At $42/cell for 280Ah I'm seriously looking at a 30kWh build. The article's 5–7 year payback probably comes out to 3–4 years for me on TOU.