Skip to main content

REopt Lite Tutorial: Financial Outputs (Text Version)

This is a text version of the video "REopt Lite Tutorial: Financial Outputs."

Let’s look at a financial analysis. The first thing you’ll see is the recommended size of each technology. In this case, a 361-kilowatt (kW) PV system and a 78-kW, 253-kilowatt-hour (kWh) battery is recommended. If you installed these technologies, they would save $209,000 over their 25-year life cycle.

The REopt Lite™ model optimizes to find the technology sizes that minimize your site’s life cycle cost of energy. It identifies the sweet spot by balancing system capital costs with utility cost savings. You could build larger systems at this site, but they would not generate enough additional savings to cover the higher capital costs. Alternatively, you could build smaller systems, but then would be leaving potential savings on the table that would more than make up for the capital cost investment.

If you get a zero size recommendation, that means the technologies evaluated are not economic based on your modeled assumptions. In other words, it’s more cost-effective for you to continue purchasing electricity from the grid. You could use the back button to return to the REopt Lite inputs page and try alternative assumptions, such as lower technology costs or higher incentives.

Scrolling down, you’ll see the System Performance Year One section. This graph shows you what the technologies are doing on an hourly basis. The load is shown in a solid black line, and the PV, battery, and grid combine to meet that load. 

Here, the PV system in red is producing electricity during the day. The battery system in blue is dispatching in the early morning or late afternoon when the PV system isn't producing electricity, but the time-of-use rate is still fairly high. The excess PV above the load is charging the battery or exporting back to the grid after the battery is fully charged. The grid electricity—what you're still purchasing from your utility—is shown in gray. You can see a distinct plateau—that's the model setting your new demand level for the month.

You can zoom in and out on this graph or scroll to see different days of the year. You can also turn different technologies on and off by clicking on the legend. The whole year’s dispatch data can be downloaded at this link.

Scrolling down, you’ll find more detailed information about these results. This table compares the business-as-usual case, which is what you would expect to pay if you didn't install these technologies, to the optimal financial case recommended by the REopt Lite model. In this column you can see the difference between these two. You can look at things like your energy costs compared to your demand costs and fixed charges, both in year one and over the life cycle of the analysis.

At the bottom of the table is the net present value, or the savings over the 25-year analysis period. These are also detailed in the pro forma spreadsheet, which you can download.

These last two sections highlight some of the limitations of the model that you should be aware of, and recommend next steps to take before moving ahead with project development.