毫无疑问，太阳能在全世界的应用已经越来越广泛。但是现在太阳能应用有多种规模和形式，未来五到十年哪种会成为主流？
这是一个合乎时宜的问题，因为太阳能产业在今天是极端的课题。大规模集中太阳能发电厂给沙漠一个未来派的感觉，并承诺城市电力数千兆瓦的供应。与此同时，安装在服装上的微型光伏电池也可以为一个人的手机提供充足的电量。小型应用和大型规模都能生产实用能源，太阳能也因此在可再生能源市场拥有一个令人羡慕的地位。因为我们不能一边走一边拿着风机为我们的iPods供电，也不能在自家后院建立生物质发电厂来加热我们的游泳池。从另一方面说明，太阳能已经渗透我们的生活，无论是小装置还是大电厂。尽管这些技术都很炫目，但老式的太阳能屋顶仍然是行业的中流砥柱。
Principal太阳能公司首席执行官迈克尔高登说：“在电力企业中，我们看到一些实用约束条件推动太阳能分成数个利基。我们期望市场能提供更加专业化的产品，并且集中体现不同规格产品的优势。”近几年光伏产业经历了一个令人瞩目的崛起，甚至可以说是经济喷射。根据光子咨询公司出版的报告显示，从2005年至2011年全球光伏发电装置安装量增加了16倍。在欧洲，德国、西班牙和意大利都一马当先。位于马萨诸塞州的研究公司预计今年年底德国装机量会达到25GW，这相当于15%-20%的电力容量，将近30%的峰值负载。
然而，不是所有人对何种规格和类型的太阳能产品能成为未来的主导达成一致。其中两种类型——分布式发电和公用事业规模项目——面临某种最大的市场竞争。分布式发电系统往往被放置在家庭和企业的屋顶，而公用事业规模的项目往往是建在地面上。屋顶系统在为建筑提供电力上占主导地位地，公用事业规模的项目往往服务较大的电网。当然，屋顶系统产生的电力要少的多。
为什么它们之间会有市场竞争？西屋太阳能首席执行官巴里辛纳蒙指出，公用事业明确地受益于一种形式，而不是其他。公用事业规模的项目提高公用事业的底线，增加费率基准，并增加公用事业可供出售用户的发电量。而规模较小的分布式屋顶系统，从另外一方面讲会产生相反的效果。如果用户自己安装了太阳能屋顶，那么它们就不会向公用事业购买电力了。“太阳能应用都是好的，只是这两种模式之间有一点冲突，”辛纳蒙说。“这是一个零和博弈的游戏。用户为了节约公用事业电力而安装了太阳能屋顶，然后用户将不再需要购买公用事业的电力。”
尽管一些公用事业反对屋顶太阳能安装，它仍然在一片欢迎中快速普及。例如，据报道加利福尼亚2010年屋顶太阳能安装量增长47%，并还会在2011年创造另外的记录。德国小型分布式太阳能系统去年增长了132%，意大利，法国和捷克共和国也看到了戏剧性的增长。截止到2015年，中国目标是安装3GW的屋顶太阳能。
柏林的PvXchange在监控国际太阳能趋势上处于优势地位，其经营的经纪人业务及网上交易平台连接了7,500多个太阳能电池组件的买家和卖家。该公司成立于2004年，专门从事太阳能组件、逆变器和完整系统的贸易。PvXchange北美总经理 Elliott Gansner 说：“在欧洲，特别是意大利和德国，商业分布式发电装置和总容量占绝大多数。”他说，100KW或者更少的屋顶太阳能，弥补了在德国安装的优势。
过去十年的早期部分，德国主要集中在住宅太阳能的发展。然后，一旦太阳能市场快速发展，更多的地面安装太阳能系统建成，许多大型项目的公用事业规模系统连接入网。这在一段时期里非常多。但后来人们很快发现市场又回到了太阳能屋顶，因为德国进料关税计划没有为地面安装提供任何的激励机制。
那么，是什么力量推动美国今天的公用事业规模太阳能呢？联邦政府从2008年开始，让公用事业赚取30％的联邦税收抵免，这是政府以前不会考虑的。此外，美国公用事业加快大型电力项目建设，或者至少参与合约，国家积极制定可再生能源标准，绿色能源确定日期决定权力的百分比。此外，国家对禁止公用设施建设和拥有发电厂的规则越来越宽松，尤其是可再生能源。例如，马萨诸塞州在2008年通过了一项法律，让公用事业拥有并经营50MW的太阳能项目。康涅狄格州在2011年6月通过了一项类似的异常自由化规则，让公用事业拥有自己的30MW可再生能源发电。
既然有这种激励动机，那么为什么Gansner还有一些其他人相信分布式发电将最终战胜公用事业规模的项目呢？当谈到太阳能发电，规模经济往往会出现一种有点有悖常理的方式。我们通常认为，一个大的实体要比许多小的实体更有效率，就是一个集中的电厂提供能源最具成本效益。但是根据Gansner的说法，我们需要重新解读这一概念。他说，对于太阳能，分布式发电提供了最高的效率。它不仅避免新的输电线路的需要，而且还提供了一个简单的方法来安装许多小型发电厂，绕过监管部门批准的麻烦。“分布式太阳能发电是一种模块化应用的理想技术，多个小系统安装会很便捷。”
此外，随着组件价格的下降，行业也着眼于降低组件安装成本，并出现了一些新的技术和工艺。例如，在德国和美国设有办事处的泽普太阳能，提供技术设计以减少安装成本。地面安装或屋顶安装的第一步，几乎无一例外是安置铝轨的长套，这消耗了大量的时间和自然资源。泽普摒弃了传统的太阳能电池板的安装块使用的铝轨，而是用无轨的方法提供分布式发电和公用事业规模项目。其系统采用面板安装方式内置沟，将住宅安装成本削减了30%-50%。这种无轨系统消除了在安装时所花费的时间，但也降低航运铝轨成本。也有公司放弃了传统的太阳能组件，直接将太阳能融入建筑构件，比如屋顶瓦，还有澳大利亚Dyesol的智能窗。这些技术在未来5到10年市场将变得变得强大和普遍，追求能源自给的大厦业主对一趋势的日益关注，将全面推动分布式发电的技术。
所以到目前为止，似乎家庭和企业屋顶的分布式光伏发电，将继续成为太阳能产业的基石，和其技术一起应用于世界的各个角落。太阳能利用技术和产业已由技术开拓期步入蓬勃发展时代，一个大规模利用太阳能的时代已经开始。哪里有光，哪里就有太阳能。
Distributed PV Still Be Mainstream of Market Short-term
The world is using more and more solar energy; of that there is no doubt. But solar comes in many sizes and shapes. Which will prevail in the coming five or 10 years?
This is a legitimate question because today’s solar industry is a study in extremes. Massive concentrating solar plants give deserts a futuristic feel and promise thousands of megawatts to power cities. At the same time, tiny photovoltaic cells installed in clothing provide just enough energy for a person’s mobile phone. With its ability to produce useful energy on both a small and large scale, solar holds an enviable position in the renewable energy market. We can’t walk around holding windmills to charge our iPods, nor do we build biomass plants in our backyards to warm our swimming pools. Solar, on the other hand, permeates our electricity system from gadget through grid-scale. And, despite the dazzle of these technologies, old-fashioned rooftop solar continues to be the industry mainstay.
"In the electricity business, we see some practical constraints pushing solar power into several niche sizes. We expect the market to offer ever more specialised products that focus their benefits on these size ranges," says Michael Gorton, CEO of Texas-based Principal Solar. The PV industry has experienced nothing short of a spectacular rise in recent years, even as the economy sputtered. PV installations increased 16-fold worldwide from 2005 to 2011, according to the report published by Photon Consulting. In Europe, Germany, Spain and Italy have led the way. Germany alone is expected to have 25 GW installed by the end of this year, which is equal to 15%-20 percent of its electric capacity and about 30% of peak load, according to the Massachusetts-based research firm.
Yet not everyone agrees on exactly what’s ahead for the various sizes and types of solar. Two types – distributed generation and utility-scale projects – face some of the greatest market rivalry. Distributed generation tends to be placed on the roofs of homes and businesses, while utility-scale projects are often built on the ground. And, while rooftop solar predominantly feeds power to a building, utility-scale projects tend to serve the larger electric grid. Rooftop systems, of course, produce less energy.
Why the market rivalry? Barry Cinnamon, CEO of Westinghouse Solar, points out that utilities clearly benefit from one form and not the other. Utility-scale projects boost the utility’s bottom line, add to the rate base and increase the amount of generation utilities have available for sale to customers. Smaller, distributed systems on rooftops, on the other hand, have the opposite effect. After homeowners install rooftop solar, they buy less power from the utility. "All solar is good but there is a little bit of conflict between those two models," Cinnamon says. "It is a zero-sum game. You save utility electricity by installing solar on your roof; you don’t buy it from the utility."
Despite some utility resistance to rooftop solar, it continues to grow in popularity. California, for example, reported a 47 percent rise in rooftop solar in 2010 and is on track for another record-setting year in 2011. In Germany small distributed capacity, most of it solar, increased 132 percent last year. Italy, France and the Czech Republic also saw dramatic growth. China is pushing for 3 GW of rooftop solar by 2015.
PvXchange is well positioned to monitor international solar trends. The Berlin-based brokerage and online trading platform connects 7,500 buyers and sellers of solar components. Founded in 2004, the company trades solar modules, inverters and complete systems. "In Europe, especially Italy and Germany, the vast majority of installations and total capacity is in commercial distributed generation," says Elliott Gansner, PvXchange’s general manager for North America.Rooftop solar, especially systems of 100 kW or less, make up the preponderance of installations in Germany, he says. In the early part of the last decade, Germany focused mostly on residential development. Then, once the solar market "found its feet and started growing" more ground-mounted solar systems were built, many in the form of large projects — utility-scale systems that feed the grid, rather than distributed generation. "And for a while there was quite bit of that. But quickly in Germany you saw a move away from that and back to rooftop," he says. In fact, the German feed-in tariff does not offer any incentives for ground mount.
What’s driving today’s push for utility scale solar in the U.S.? The federal government in 2008 began letting utilities earn a 30 percent federal tax credit, which they had previously been denied. In addition, U.S. utilities are increasingly building large power projects, or at least contracting with them, in states with aggressive renewable portfolio standards—requirements that a percentage of power come from green energy by specific dates. In addition, liberalised states are increasingly easing rules that prohibit utilities from building and owning generating plants, at least when it comes to renewable energy. Massachusetts, for example, passed a law in 2008 that lets utilities now own and operate up to 50 MW of solar. In June 2011 Connecticut passed a similar exception to its liberalisation rules, and now lets utilities own up to 30 MW of renewable generation.
So with this kind of motivation for utilities, why do Gansner and other believe that distributed generation will ultimately win out over utility-scale projects? When it comes to solar energy, economies of scale tend to emerge in a somewhat counterintuitive fashion. We think that one large entity offers greater efficiency than many small ones; that is, a centralized power plant delivers energy most cost-effectively. That’s a notion we need to abandon, according to Gansner.When it comes to solar, distributed generation offers the greatest efficiency, Gansner says. Not only does it avert the need for new transmission lines, but also offers an easy way to install many small power plants, one that bypasses the hassle of regulatory approval. "Solar distributed generation is an ideal technology for modular application. It is easy to install lots of small systems. "
With panel prices dropping, the industry is now setting its sights on lowering the cost of installing panels, and several new technologies and techniques are emerging. For example, Zep Solar, with offices in Germany and the US, offers technology designed to reduce installation costs. The first step for ground-mount or roof installations, almost without exception, is placement of long sets of aluminium rails. This consumes a lot of time and natural resources. Zep does away with the aluminium rails used as mounting blocks for conventional solar panels and instead offers a trackless approach for both distributed generation and utility-scale projects. Zep says that its system, which uses panels that mount by way of a built-in groove, cuts residential installation costs by 30 – 50 U.S. cents/watt and speeds installation time by a factor of five. Such rail-free systems eliminate the time spent on installation, but also cut the costs of shipping the aluminum rails, say proponents of the approach. Other companies are foregoing the traditional solar panel and integrating solar directly into elements of the building, such as rooftop shingles, or in the case of Australia-based Dyesol, windows. The technology becoming strong and prevalent in the marketplace in the next five to 10 years as building owners become increasingly concerned about utility costs and energy self-sufficiency, a trend he says will spur distributed generation overall.
So far now, it appears that PV as distributed generation, the kind found on the roofs of homes and businesses, will continue to be the bedrock of the solar industry，and together these various technologies will reach into all corners of world. Solar technology and industry have stepped into the flourishing period from the development period,a large-scale use of solar energy has begun. Where there is light, there will be solar.
