Lifespan of Solar Panels: Calculating Depreciation in the Balance Sheet
For a business owner, installing an energy asset is a financial move that must generate a clear and measurable return. From this perspective, correctly assessing the lifespan of solar panels in a business is the key factor in calculating the payback period and forecasting the cash flows generated by self-consumption.
An industrial photovoltaic system should not be viewed as a rapidly depreciating asset; on the contrary, it is a long-term asset whose ability to resist photovoltaic system obsolescence depends on the quality of its components and the maintenance strategy adopted.
Table of contents
What is the actual lifespan of industrial solar panels?
| Years in operation | Estimated performance (Tier-1) |
|---|---|
| Year 0 | 100% (Nominal power) |
| Year 10 | ~95% |
| Year 20 | ~90% |
| Year 25 | ~85% |
This efficiency profile is the foundation of a stable payback plan and makes it possible to calculate return on investment (ROI) without technical uncertainty.
Depreciation of a photovoltaic system and accounting treatment
The depreciation of a photovoltaic system should reflect the asset’s technical longevity. From a tax perspective, it is necessary to distinguish the accounting classification of the installation in order to determine the correct depreciation rate:
If the system is classified as a movable asset, the depreciation rate for a corporate photovoltaic system is often 9% per year.
If the system is registered as an immovable asset (an increase in the value of the building), the rate may fall to 4%.
Considering that the lifespan of solar panels exceeds 25 years, the company is in a position of competitive advantage: once the tax depreciation period has ended, the system continues to operate with extremely low operating costs for at least another decade. Constantly monitoring photovoltaic system obsolescence through professional O&M services also makes it possible to plan revamping interventions in order to maximize the long-term profitability of the company roof.
FAQ – Domande frequenti
The estimated operating life commonly exceeds 30 years. However, the standard performance warranties provided by manufacturers usually cover a period of 25 years, ensuring that efficiency does not fall below 80–85% of nominal power.
Based on a linear degradation rate of 0.5% per year, after 10 years a high-quality module retains about 95% of its initial performance, ensuring stable energy production.
From an accounting perspective, it is treated as a capital asset. The reference tax depreciation rate is generally 9% for movable systems, allowing the cost to be spread over about 11 years, compared to a much longer useful life of the asset.
The ageing of materials leads to a marginal and predictable reduction in electricity production. Through professional monitoring, this natural decline can be managed, ensuring that the business plan remains aligned with expected energy savings.
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