小编
在德国，许多光伏组件都污染非常严重，这包括光伏电站暴露在非常繁忙的街道附近的极端环境污染、鸟粪等。如果污染物不经常除去，污染可造成发电量损失，在某些情况下可导致组件的不可逆损伤。从光伏组件的技术角度来看，清洗感觉是很有必要，但是电站主人是否计算过清洗与发电收益的关系呢？
在大多数情况下，在雨天的自清洁不会删除所有的污垢，自洁效果高度依赖于组件的坡度（越小的斜面角度，清洁效果就越小）。此外，组件的设计也起着至关重要的作用。例如，使用无框光伏组件，自来水在清洗时很少会有叶子或沉积物留在组件边缘。
如果光伏组件暴露于以下任何一种变脏的条件下，应予以考虑定期清洗。
从牛圈舍通风系统的有机物质
从烟囱排出的废气
从附近的道路和工业废气
从农业饲料粉尘
鸟粪
从树的叶子和花
像地衣，藻类和苔藓植物的生长
当你决定要清理光伏系统的组件，你还应该评估对发电量改善的效果。下面是一个例子，我们看下组件清洁对光伏发电量表现的影响。
发电量前后比较
100 kWp的光伏系统的清洗前后的收益表现。一个位于一个堆场工厂的屋顶，另一个是附近没有特别的污染的光伏系统作为参考。这两个PV系统均处于可靠运行期间。
图1
图1显示了光伏电站（蓝色）的月度发电量，参考光伏电站（红色）和是没有清洗的。该光伏电站五月24号被清洗过，经测量清洁后发电量显著提高超过15％，仅两个月没有清洗后月发电量再次跌破参考，并不断降低随着时间的推移。绿色条显示其预期收益率和每月是否没有清洗的关系。清洁造成从6月至12月每月提高产量加起来达到11kWh。在上网电价€0.33/千瓦时的情况下，这相当于€3.630。100 kWp的光伏系统的清洁费用为€1.430。清洁服务后七个月获得的利润已经是€2200，所以电站主人应该乐了。
原文：
PV Module Cleaning – does it pay back?
Many photovoltaic plants in Germany are exposed to heavy soiling. This ranges from PV plants that are located next to very busy streets exposed to extreme pollution or bird droppings. Pollution causes yield losses and in some cases irreversible damage to the modules if the contaminants are not frequently removed. From a technical perspective cleaning of PV modules makes a lot of sense in most cases, but does it calculate for the PV owner?
There are numerous reasons which are responsible for the contamination and the self-cleaning during rainy days will not remove all dirt in most cases. And the effect of self-cleaning is highly dependent on the slope of the modules – the smaller the angle of the slope, the less the effect will be. Further, the design of the modules also plays a crucial role. For example when you look at frameless PV modules the running water leaves less sediments at the edge the module. If PV modules are exposed to one or more of the following reasons of soiling, a regular cleaning should be considered.
- Organic substances from ventilation systems of cattle sheds
- Exhaust air from smokestacks
- Exhaust from nearby roads and industry
- Feed dusts from agriculture
- Bird droppings
- Leaves and flowers from trees
- Growth of plants like lichen, algae and moss
When you decide to clean the modules of a PV system you should also assess the effect on yield improvement. Here is an example how we looked at the impact of the module cleaning to the PV yield performance.
Comparison before / after cleaning
The yield performance of a 100 kWp PV system before and after cleaning. The facility is located on the roofs of a stockyard. A nearby PV system, without particular pollution load was used as reference. Both PV systems were running without fail in the period under review.
Figure 1 shows the monthly energy yield of the PV Plant (blue), the reference PV plant (red) and the prognosis for the PV Plant without cleaning. The PV plant was cleaned on the 24th of May. After cleaning a significant yield increase of more than 15 percent was measured and only two months after the cleaning the monthly yield dropped again below the reference and continuously degraded over time. The green bars show a prognosis for the expected monthly yields if no cleaning would have been performed. The monthly yield improvement caused by the cleaning for the period from June to December adds up to 11.000kWh. In the case of a feed-in tariff of 0.33 €/kWh, this corresponds to 3,630 €. The cleaning cost for the 100 kWp PV system is 1,430€. The profit gained seven months after the cleaning service is already 2,200 €. The PV owner smiles.
Written by
Johannes Maison
