How an old concept can kickstart new U.S. solar

Clean energy advocates almost universally revere Germany, myself included. Oft-heard declarations include: "Did you know solar energy costs half as much in Germany as it does in the U.S.?"

好吧，我要再次谈论德国，但是这次标语是完全不同的。德国只能安装3.9 gigawatts of solar in 2013, down from 7.5 GW last year. That means the U.S. finally might install more solar in a single year than Germany.

This decrease is largely attributable to a fundamental shift in the value proposition of solar in Germany. Understanding this dynamic provides perspective on perhaps the most contentious renewable energy topic in the U.S. today:净能量计量(NEM). With net metering, electric utilities provide credit to customers with solar PV systems for the full retail value of the electricity they produce. If a customer produces as much electricity as they consume, their bill "nets out" to zero or to any minimum monthly customer charges. That means customers don't pay for electricity, but it also means they aren't paying anything towards the utility's fixed costs, such as existing generating assets that produce electricity when the sun isn't shining or distribution lines.

随着越来越多的客户通过净能量计量来零或大大减少账单，较少的客户涵盖了这些固定成本和费用。对于大多数公用事业来说，这没有多大意义，因为太阳能客户仍然依靠网格来满足其大部分电力需求。

The German solar market: FiT for a change

Germany took a different approach. In 2000 the German government launched a massive ratepayer-subsidized campaign to expand solar energy deployment -- the solar feed in tariff (FiT) program that made renewable energy generation more affordable. With high solar equipment costs, the Germans set FiT levels well above the retail price of electricity in order for solar systems to make economic sense. This led to new investment, a multi-year explosion in solar installations and large scale reductions in PV equipment costs.

合适的帮助政府满足某些能力目标。像大多数补贴一样，随着时间的推移，它们随着时间的推移而逐步淘汰，每千瓦小时（kWh）满足不同的目标，从而导致拟合水平下降。德国适合住宅系统是set at $0.20/kWh, 2.5 times lower than in 2010.

Unlike the situation stateside where customers are credited for their solar generated electricity at the full retail electricity rate under NEM, most German systems only are credited at the current FiT rate ($0.20/kWh). German residents, on the other hand, pay on average $0.36/kWh for electricity in their homes. This discrepancy is the primary reason why German solar businesses are developing new product offerings.

可以自我消费是答案？

Enter an old concept that has yet to break into U.S. vernacular:self-consumption. It's simple. Instead of feeding all of your system's solar energy production back into the grid and being credited for each kWh at the FiT level, solar installation companies configure a PV system using an additional meter so that each kWh produced by your PV system gets special treatment depending on where it's used:

•如果您在家庭或企业中使用光伏系统中的太阳能，则您以零售电力率（上面的黄色线）“归功于”，因为您没有从公用事业中购买它
• If your solar system produces more electricity than you need, you send that excess electricity back to the grid, and are credited at the FiT rate
•当您的太阳能系统没有发电或建筑物的负载超过生产时，您会以标准零售价从公用事业中购买额外的电力

从拟合到自我消费只是财务方程的一小部分。通过自我消费，建筑所有者和租户都被激励在现场使用尽可能多的太阳能。这意味着要进行诸如安装符合负载的东西方系统，购买设备用于太阳能生产的时间，以及在频谱的尽头，安装电池存储系统。这些技术使德国客户可以从现场使用其太阳能的三分之一到现场高达75％。

Self-consumption also drives energy conservation because the more families and businesses conserve energy, the greater share they can displace with their own solar generation. This can increase demand and grow the market for energy efficiency and management devices.

美国的自我消费

由于对公用事业和监管机构对净能量计量的兴趣，零售电力率越来越高的零售电力率越来越高的零售电力率越来越高。自我消费有可能改善与NEM相关的许多问题。除了为客户和公用事业提供公平的补偿外，自我消费还有助于减轻非极性客户的交叉补贴问题，从而通过为不同的来源和使用清晰的价值和使用，从活力。

Self-consumption won't manifest here overnight for two main reasons. First, there's a massive absolute cost difference: theaverage residential electricity rate in the U.S. is $0.13/kWh, just under one-third of Germany's, so the impact of offsetting retail rates instead of using a specialized tariff aren't as drastic in the U.S. Second, utilities, or perhaps public utility commissions, would have to approve self-consumption by clearly delineating billing structures and agreeing to some kind of value of solar rate as described above.

But these limitations can be overcome, probably before 2020. If PV system costs are able to hit the Department of Energy's阳光目标尽管我们的“低”电率，太阳能仍将具有令人信服的价值主张。随着美国公用事业和太阳能倡导者在净能量计量的范围之外寻找下一步，我们应该向现在处理这些问题的欧洲同行学习。寻找对所有利益相关者（包括非参与太阳能客户及公用事业）的系统配置和速率结构，很少。

And while self-consumption is not a panacea, its potential benefits to multiple stakeholder groups make it worthy of further consideration, especially as the net energy metering issue comes front and center for more utilities across the country.

太阳能电池板图像通过Shutterstock.

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