How OpenSolar calculates financial savings

Summary:

When creating a proposal in OpenSolar, several key financial figures are calculated to show your customer the value of going solar. These include estimated savings, system costs, payback periods, and more. This article walks you through:

• What inputs drive these calculations

• How to configure financial assumptions

• How to customize the proposal to highlight financial metrics

• How the financial tables (such as Bill Savings and Detailed Financial Benefits) are calculated

Core Inputs that Impact Financial Outcomes:

OpenSolar's financial outputs are driven by three main categories:

1.  Customer Energy Usage & Utility Bill

OpenSolar models the customer’s current and post-solar utility bill based on:

• Annual electricity consumption (kWh/year)

• Usage profile (daily or monthly patterns)

• Utility tariff (rates before and after solar installation)

Where to set this up:
Project > Energy

There, you can:

• Input customer energy usage

• Define time-of-use patterns

• Select an applicable utility tariff

Note: Manually created utility rates may occasionally cause issues. If your desired rate isn’t available, we recommend sending the utility rate sheet to OpenSolar support, and our team will add it to the system.

2. System Design & Performance

The design of the solar system significantly influences generation and savings. Key factors include:

• Equipment specs (module and inverter efficiency)

• System layout (slope, azimuth, orientation)

• Battery inclusion and settings (charge/discharge)

• Shading and environmental factors

• Inverter configuration (string vs. microinverter)

Verified Accuracy: OpenSolar’s modeling accuracy has been third-party tested by PVEL.

Where to configure:
Project > Design

Use this tab to fine-tune system specs and expected generation based on site conditions.

3. Financial Simulation Settings

Once energy savings are calculated, OpenSolar projects lifetime financial outcomes using:

• System price

• Available incentives

• Payment method (cash, loan, lease, etc.)

• Simulation settings (energy price inflation, analysis duration)

💡 Where to adjust:
Project > Pricing and Control > Proposal Template

Customizing the Proposal to Show Financial Impact:

Admins can customize which financial metrics appear in the PDF or Online Proposal. You can highlight or hide data based on your sales strategy.

Available Financial Metrics to Highlight:

• Total utility savings

• Payback period

• Discounted payback

• Net Present Value (NPV)

• First-year savings

Available Tables to Include:

• Bill Savings Table

• Detailed Financial Benefits Table

How Financial Tables Are Calculated:

Bill Savings Table:

Displays monthly breakdowns of utility savings.

Calculation logic:

• Solar Generation: Based on system output adjusted for weather.

• Consumption: Taken from the Energy tab input.

• Utility Before Solar:
  Formula:
  Monthly usage x rate + fixed utility charges
  Example: 1042 kWh × $0.115 + $10 = $130.83

• Utility After Solar:
  Formula:
  (Monthly usage – solar offset) × rate + fixed charges
  Example: (1042 – 507) × $0.115 + $10 = $67.71

• Estimated Savings:
  Utility Before Solar – Utility After Solar
  Example: $130.83 – $67.71 = $63.12

Detailed Financial Benefits Table:

Provides a year-by-year financial overview.

Field Definitions:

• Electricity Consumption: From the Energy tab.

• Solar Generation: Based on modeled annual output.

• Utility Before Solar: Total of the "before" column from the Bill Savings Table.

• Utility After Solar: Total of the "after" column from the Bill Savings Table.

• Annual Savings: Total of the estimated monthly savings.

• System Costs:

  • Year 1 = System price

  • Years 2+ = Price – incentives (amortized if applicable)

• Upfront Incentives: Pulled from the Incentives tab in the Design section.

• Net Savings:
  Annual Savings – System Cost

• Cumulative Impact:
  Carries forward each year’s net savings.
  Example:

  • Year 1 = -$130

  • Year 2 Net = +$18

  • Cumulative = -130 + 18 = -112

Final Tips:

• Use proposal templates to emphasize key financial data based on customer type (residential, commercial, etc.)

• Keep energy price assumptions updated to reflect local trends

• Always verify incentives and ensure accuracy in tariff selection