Solar inverter: reliability > conversion efficiency, scene selection is the key.
Give the core conclusion first:
Long-term household/industrial and commercial power station: reliability priority is much higher than conversion efficiency;
High electricity price, small space and extreme income scenario: the efficiency weight is greatly improved, but the basic reliability cannot be sacrificed;
It is not a choice between the two. It is the optimal solution to ensure the reliable bottom line first and then pursue high efficiency.
1. Why is reliability more important?
Inverter is the only high-voltage device in photovoltaic system, and it is the core with high failure rate, which determines whether the power station can generate electricity stably for 20~25 years (the life of photovoltaic panels).
The downtime loss is far greater than the efficiency gap.
The efficiency gap of ordinary inverters is mostly only 1% ~ 3%;
However, once the inverter fails to stop and power is generated all day, the loss in a few days will offset the efficiency difference for several years.
Maintenance cost & hidden danger is extremely high
Outdoor exposure, rain, high temperature environment, inferior inverter is easy to blow up, burn the motherboard, leakage protection trip;
The maintenance cost of industrial and commercial roofs and mountain power stations is extremely high, and the replacement cost after over-warranty is expensive;
Frequent failures of poor products will also affect the life of photovoltaic panels and distribution boxes and cause safety risks.
Warranty determines the whole life cycle value.
First-line brand inverters are generally guaranteed for 5/10 years, and reliable models can run stably for 20 years;
Low-priced and low-quality models will decay and fail in 1-3 years, but the total cost of replacing them later will be higher.
Second, the true value of conversion efficiency (not as big as you think)
The benefit of efficiency difference is limited.
Give a straightforward example:
10kW photovoltaic power station, the high efficiency machine is 98.5%, and the common reliable machine is 96.5%, with a difference of 2%.
The annual power generation is about 12,000 kWh, only 240 kWh a year;
According to 0.6 yuan/kWh electricity price, the difference is only 144 yuan a year.
Even if it costs hundreds of dollars to buy efficient models, it will take several years to return to the original.
Nominal efficiency ≠ Actual efficiency
The maximum conversion efficiency marked by the manufacturer is the ideal working condition;
Every morning and evening, under cloudy days and low load, the efficiency of all inverters will decrease, and the gap between inefficient intervals will be greatly reduced.
Ultra-high efficiency often comes with a price.
Extremely efficient model, the component load is more extreme, the heat dissipation margin is smaller, and the reliability decreases in long-term high temperature environment.
