綠色電力可以通過幾種不同的方式採購，但是，所有形式的綠色電力供應和消耗都包括可再生能源證書（RECs）。如果機構選擇採購綠色電力，則可以根據所在州的監管條件從當地的配電公司，有競爭力的電力供應商，或直接從可再生能源發電廠採購綠色電力。即使在沒有綠色電力零售商且公用事業公司不提供綠色電力選項的州，美國的任何機構也都可以將RECs作為獨立產品購買，不與機構的電力採購捆綁。對於正在考慮擁有或租賃綠色發電設施的機構，計劃發電地點的可用能源（例如太陽能，風能，生物質能）是確定項目可行性的首要考慮因素。自發電不僅限於現場機會如屋頂太陽能光伏發電，尤其是大型機構可能會考慮擁有場外發電，這樣項目選址可能更具成本效益，可選資源也更豐富。
市場上的供應選項範圍提供了相當大的靈活性。機構在做採購決策時可以考慮如價格、長期節約成本、發電資源類型（如風能與太陽能）、易於採購、需求側選擇的直接和間接影響、以及發電設施所在地等因素。通過這些選擇，機構通常可以找到滿足其目標期望的綠色電力產品。
第2章介紹了REC，並強調了REC作為可再生能源發電和使用的跟蹤和核算工具的作用。RECs的所有權和註銷作為聲明和分配可再生能源使用及其環境屬性的基礎，對於本章討論的每個綠色電力選項以及美國所有的綠色電力採購選項是非常重要的。如下文所述，RECs也作為獨立的採購選項或產品供應。尤其在討論這些選項和RECs時，必須弄清何時將RECs作為對所有綠色電力產品選項重要的跟蹤工具，何時作為獨立或非捆綁式供應產品。還需要注意的是，所有供應選項都包括RECs，RECs傳遞了屬性的所有權以及聲明在共享公共電網上使用了可再生能源的權利。
本指南確定了六種常規的綠色電力供應選項，包括四類的綠色電力採購選項和兩類自發電選項，如圖4-1所示。其中一些選項在附錄B（商業太陽能融資選項）中進行了更詳細的描述。
Figure 4-1. Voluntary Green Power Supply Options
Green power can be procured in several different ways, however, all forms of green power supply and consumption include renewable energy certificates (RECs). If an organization chooses to purchase green power they may procure it from a local distribution utility, from competitive power suppliers, or directly from a renewable energy generator, depending on regulatory conditions in the state. Even in states where there are no green power retail suppliers and the utilities do not offer a green power option, any organization in the United States can buy RECs as a stand-alone product, 「unbundled」 from the organization’s electricity purchases. For organizations considering owning or leasing green power generation facilities, the energy resources (e.g., solar, wind, biomass) available at the proposed generation site are an important initial consideration in determining a project’s feasibility. Self-generation is not limited to on-site opportunities such as rooftop solar photovoltaic. Large organizations in particular might consider owning offsite generation where project siting may be more cost-effective and resource options more abundant.
The range of supply options in the market provides considerable flexibility. Organizations can consider factors such as price, long-term cost savings, generation resource type (e.g., wind versus solar), ease of procurement, the direct and indirect effect of their demand-side choices, and the location of the generating facility in their purchasing decisions. With these choices, organizations can usually find a green power product that will meet their desired goals.
Chapter 2 introduced the REC and emphasized its role as the tracking and accounting instrument for generation and use of renewable energy. As the basis for claiming and allocating the usage of renewable energy and its environmental attributes, ownership and retirement of RECs are essential with each green power option discussed in this chapter and all green power purchasing options in the United States. As discussed in more detail below, RECs are also offered as a stand-alone purchase option or product. When discussing these options and RECs in particular, it is important to clarify when one is referring to RECs as a tracking instrument essential to all green power product options, or to RECs as a stand-alone or unbundled product offering. It is also important to note that all supply options include RECs which convey ownership of the attributes and the right to claim renewable energy usage on a shared grid.
This document identifies six general green power supply options, including four types of green power purchase options and two types of self-generation options, as shown in Figure 4-1. Several of these options are described in more depth in Appendix B, Commercial Solar Financing Options.