绝大多数户用和工商业光伏都是将光伏组件安装在屋顶，不仅可以帮助业主节省电费，还可以优化屋顶空间的使用，
1.为屋顶降温。
本文将讨论在平屋顶上安装光伏电站必须了解的几个最重要的事项。
采用哪种安装形式
不同的屋顶安装光伏组件的方法也不一样，常见的安装方式包括附加型、压载型及桩基型。
如果屋顶属于彩钢瓦型式，一般都考虑附加型，直接将组件平铺在彩钢瓦上，尤其是一般彩钢瓦屋顶都没有女儿墙，采用平铺的型式防风效果最好，最为安全；另外彩钢瓦屋顶也有一定的倾角，虽然可能不是光伏发电对应的最佳倾角，但加大倾角带来的改造成本也是需要综合考量的。
对于水泥屋顶，通常是纯平，常见的安装方式是压载型和混凝土基础桩基型，如上图所示。
很多时候，建筑物业主不允许在混凝土平屋顶上钻孔，一方面是担心老建筑的强度，或者是不想改变屋顶的防水性能。这就是选择压载型或混凝土基础安装的原因。
压载型由于没有和屋顶做锚固连接，因此侧面可以考虑做防风处理，尤其是没有女儿墙的水泥屋顶。
混凝土基座的主要目的是确保即使在暴风雨季节，支架系统也能保持完好无损。它保证了良好的安装而不会导致屋顶漏水，还可以提高太阳能电池组件的效率，减少女儿墙对阳光的遮挡。
2平屋顶不代表平铺安装
在平屋顶上采用平铺方式安装光伏组件，似乎是最想当然的方式，不仅安装量/面积可以最大化，还有可能将光伏作为屋顶顶棚使用，增加空间面积。
但事实上，在平屋顶上安装光伏，并不意味着您还应该将其倾斜度设置为0度，我们需要考虑很多因素，应避免平装，包括：平铺组件容易积灰，积灰可能造成10％甚至30%的发电量损失；清洗更不方便，积水不易流出；与倾斜安装相比，发电量将减少；投资回报期将更长；可能无法靠自然降雨来去除积灰；倾斜安装和纯平铺的光伏阵列发电量会有明显的不同，通过对一个11.2kWp太阳能系统进行仿真模拟，倾角分别为10度、5度和0度。仿真结果表明，如果倾角为0度，则11.2kWp系统年发电量约为13,480.3kWh，而在5度倾角下，该系统一年发电量达到14,066.9kWh。而事实上，当倾角为10度时，该系统年发电量达到14,520kWh。从结果中可以看出，每增加5度，系统每年增加500kWh的发电量（15度后，增加量会明显减少，超过最佳倾角后反而会更低）。而且，上述仿真模拟还没有考虑低倾角安装时由于积灰而造成的发电量损失。
建议如果不愿意采用最佳倾角来安装的话，安装倾角尽可能还是高一些。如果必须平铺，建议也将倾角设计在5-10度之间。对于平屋顶来说，5-10度的角度也已经足够平了，而对于彩钢瓦屋顶来说，一般都会留有3度以上的角度，相比增加倾角的额外成本来说，顺其自然、随坡就势也是很好的选择。
3平屋顶安装必须考虑风速
在太阳能系统的设计阶段，必须考虑当地可能出现的最大风速，尤其是在风速超过每小时180公里的地区。
不是五年一遇，十年一遇，光伏系统的寿命是25年，必须考虑50年一遇！
去年4月发生在江苏南通的台风足以说明一切，随着建筑质量的提升，对于南通地区的建筑也来说，几乎没有人会过多考虑到三十年前常发生的台风灾害，毕竟南通地区的台风，也就能对以前的平方、草屋、大棚带来点影响。
但南通的那场大风，却活生生地将屋顶的太阳能光伏、太阳能热水器都吹到了地上，台风期间造成十多人死亡，50年一遇毫不夸张。
普通的平屋顶太阳能发电系统可以承受160 km/h（十三级台风）的风速，但如果没有女儿墙挡风，阵列间没有考虑防风，局部区域因气流而造成的瞬间风速会远远超过实际的风速。
这时候对于支架的选型、结构设计、压载或混凝土基础强度设计必须依赖专业机构的建议，即便是彩钢瓦屋顶的平铺，也要有科学的分析。(来源 | 光伏能源圈)

The vast majority of domestic and commercial photovoltaics are rooftop panels, which not only help homeowners save money on their electricity bills, but also optimize the use of roof space,

Step 1 Cool the roof.

This article will discuss some of the most important things to know when installing a photovoltaic plant on a flat roof.

What kind of installation is used

Different rooftop installation methods of photovoltaic modules are also different. Common installation methods include additional type, ballast type and pile type.

If the roof belongs to the caigang tile type, generally consider the additional type, directly tile components on the Caigang tile, especially the general Caigang tile roof has no parapet, the tiling type of windproof effect is the best, the most safe; In addition, the color steel tile roof also has a certain Angle, although it may not be the best Angle corresponding to photovoltaic power generation, but the transformation cost caused by increasing the Angle also needs to be comprehensively considered.

For cement roofs, which are usually flat, the common installation methods are ballast and concrete foundation pile foundations, as shown in the image above.

In many cases, building owners are not allowed to drill into flat concrete roofs because of concerns about the strength of the old building or because they do not want to change the waterproof properties of the roof. This is the reason for the choice of ballast type or concrete foundation installation.

The ballast type is not anchored to the roof, so the side can be considered to be windproof, especially the cement roof without parapet.

The main purpose of the concrete base is to ensure that the support system remains intact even during stormy seasons. It ensures a good installation without causing the roof to leak. It also improves the efficiency of the solar cell modules and reduces the shade of the parapet from the sun.

2 Flat roof does not mean tile installation

It seems to be the most natural way to install PV modules on the flat roof by tiling. Not only can the installation volume/area be maximized, but also the PV can be used as the roof roof to increase the space area.

But in fact, installing PV on a flat roof does not mean that you should also set its slope to 0 degrees. There are many factors to consider and flat installation should be avoided, including: tiled components are prone to ash accumulation, which may cause 10% or even 30% loss of power generation; Cleaning is more inconvenient, water is not easy to flow out; Compared with the tilt installation, the power generation will be reduced; The payback period will be longer; Natural rainfall may not be able to remove ash; There is a significant difference in the amount of power generated by the sloped and flat-laid PV arrays, as simulated by an 11.2kwP solar system with inclination angles of 10 degrees, 5 degrees and 0 degrees, respectively. The simulation results show that, if the inclination Angle is 0 degrees, the annual power generation of 11.2kwP system is about 13,480.3kWh, and under the 5 degrees inclination Angle, the unified annual power generation of the system reaches 14,066.9kWh. In fact, at an Angle of 10 degrees, the system generates 14,520kWh a year. From the results, it can be seen that the system increases the power generation by 500kWh per year for every 5 degrees of increase (after 15 degrees, the increase will be significantly reduced, but even lower after exceeding the optimal Angle). Moreover, the above simulation does not take into account the power generation loss due to ash accumulation during low-angle installation.

It is recommended that if you are not willing to use the best Angle to install, the installation Angle is as high as possible. If tiling is necessary, it is recommended that the inclination Angle be between 5 and 10 degrees. For the flat roof, 5-10 degrees Angle has been flat enough, and for the color steel tile roof, generally will leave more than 3 degrees of Angle, compared to increase the extra cost of inclination, let nature take its course, with the slope is also a good choice.

Wind speed must be considered in flat roof installation

In the design phase of solar systems, the maximum local wind speeds that are likely to occur must be considered, especially in areas with wind speeds exceeding 180 kilometers per hour.

Not once in five years, once in ten years, PV system life is 25 years, must consider once in 50 years!

The typhoon that happened in Nantong, Jiangsu Province in April last year is enough to illustrate everything. With the improvement of construction quality, for the buildings in Nantong area, almost no one will take too much account of the typhoon disaster that often happened 30 years ago. After all, the typhoon in Nantong area can also bring some impact on the square, grass huts and greenhouses in the past.

However, the wind in Nantong blew the solar photovoltaic and solar water heater on the roof to the ground. During the typhoon, more than 10 people died, which was the first time in 50 years.

Ordinary flat roof solar power generation system can withstand the wind speed of 160 km/h (class 13 typhoon), but if there is no parapet windscreen, the array does not consider the wind protection, the local area due to airflow caused by the instantaneous wind speed will be far more than the actual wind speed.

At this time for bracket selection, structural design, ballast or concrete foundation strength design must rely on the advice of professional institutions, even if the tile roof of color steel tile, there should be a scientific analysis. Photovoltaic energy source (| circle)