2015: Why We First Considered Installing Solar Panels
Around 2015, we received a proposal from T‑Gas to install solar panels. Although the FIT price had already dropped to 33 yen/kwh, the payback period was still around ten years. After cosidering for about six months, we ultimately decided not to proceed.
Initial Estimate (2015)
- Panel capacity: 3.5 kW
- Annual generation: 3,550 kWh
- Cost: 1.5 million yen (including installation)
- Annual benefit: approx. 120,000 yen
- Payback period: 12.5 years
Why We Decided Against It
- The system relied mainly on selling electricity back to the grid
- Panel warranty and lifespan were unclear
- Long‑term risks were difficult to assess
2023: Why We Revisited Solar Power
Over the next ten years, solar panel technology advanced significantly. Output nearly doubled, and warranties extended to 20 years. Feeling it was worth reconsidering, we requested a new estimate.
First Estimate (2023)
- Panel capacity: 5 kW (355 W per panel)
- Annual generation: 5,900 kWh
- Cost: 1.9 million yen (including installation)
Specifications had improved dramatically, and costs had decreased. Hearing that even higher‑performance panels were coming, we waited six months and requested another estimate.
Final Specifications We Chose (2024–2025)
Here is the system we ultimately decided to install:
Selected Solar Panel System
- Panel capacity: 6.2 kW (440 W per panel)
- Annual generation: 7,000 kWh
- Cost: 2.1 million yen (including installation)
Why I Decided to Install
- Significant increase in generation thanks to improved panel performance
- Rising electricity prices increased the annual benefit to around 200,000 yen
- Payback period shortened to under ten years
Although inflation pushed the cost slightly higher than expected, the overall benefits made the decision clear.
**Next Episode Preview:
Episode 2‑2 — “How We Decided to Install a Home Battery”**
In the next installment, I’ll share the story behind our decision to install a home battery (Tesla Powerwall 2).
What factors did you consider when evaluating solar power for your home?
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