SunbeltSailor

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.