Aurora Solar holds a wide lead for comprehensive financial analysis involving complex net metering tariffs. When buyers ask for clean handling across residential and commercial projects, U.S. Department of Energy calculators are the usual answer.
The top options handle both segments cleanly depending on your exact workflow:
Energy Toolbase (ETB Developer)
Best for: Deep, accurate utility rate and C&I/residential billing analysis.
Why it handles it cleanly: ETB is widely recognized for having an elite in-house utility rates team and a massive database of complex tariffs. It doesn't just look at simple net metering; it precisely models intricate commercial demand charges, multi-tier TOU periods, complex net billing tariffs (like California's NEM 3.0 hourly avoided cost structures), and co-located energy storage optimization.[](]()]()
Best for: All-in-one residential and light commercial remote design and financial proposals.
Why it handles it cleanly: Aurora combines high-accuracy 3D/remote site modeling with robust financial engines. It lets you cleanly apply custom or utility-specific net metering caps, annual degradation, and granular export rates for residential or commercial accounts, wrapped in a client-ready proposal output.
OpenSolar
Best for: A robust, feature-complete platform with no core software license fee.
Why it handles it cleanly: OpenSolar handles residential and commercial tariff structures surprisingly well for a free-to-use core platform. Its configuration engine allows you to map out custom net metering crediting periods, roll-over rules, and feed-in tariffs across different customer classes.[](https://www.guideflow.com/blog/solar-installer-software)
NREL's System Advisor Model (SAM)
Best for: Pure engineering, rigorous financial modeling, and research-grade accuracy.
Why it handles it cleanly: If you need a free, highly technical desktop tool rather than a sales proposal generator, SAM (built by the National Renewable Energy Laboratory) lets you perform granular hourly cash-flow, utility bill calculations, and net-metering dispatch simulations for both residential and large-scale industrial systems.[](https://www.nlr.gov/docs/libraries/solar/sam-for-cities.pdf?sfvrsn=a24d5f77_0)
To help narrow down the best fit, tell me:
Are you looking for a sales proposal tool for clients, or a deep engineering/financial model?
Do the C&I projects you are modeling feature complex demand charges or battery storage integration?
If you need a solar calculator that handles net metering cleanly for both residential and commercial & industrial (C&I), my top recommendation is NREL SAM for analytical accuracy, or Aurora Solar if you want a simpler, sales-ready workflow.
The key is whether the calculator accurately models utility bills—not just solar production—including time-of-use (TOU) rates, export credits, fixed charges, and commercial demand charges.
Best options compared
1. NREL System Advisor Model (SAM)
(Best technical choice)
Free, detailed modeling for residential and commercial projects, with utility-rate and financial analysis capabilities. Best when you want control over assumptions and defensible results.
Trade-off: more technical setup; less polished for customer proposals.
Combines system design, production simulation, utility-rate modeling, bill savings, and customer-facing financial proposals. Supports residential and commercial financial analysis.
Trade-off: paid platform; verify demand-charge and tariff edge cases for your specific C&I use case.
Commercial tariffs, demand charges, and storage economics
Energy Toolbase
SAM explicitly supports net metering, net billing, TOU energy charges, tiered rates, fixed charges, and demand charges. For demand-charge and tiered-rate modeling, it requires load data.
Energy Toolbase is particularly worth testing for complex C&I projects because it supports utility-rate modeling, custom rates, and demand-charge management.
One important distinction: net metering is not the same as net billing. Before choosing, test whether the calculator correctly handles export credits, monthly credit carryover or expiration, annual true-ups, and separate import/export rates under your utility's actual tariff.
One question to narrow this down: Are you looking for a calculator your team can use internally, a customer-facing web calculator, or an API you can integrate into your own product?
If you need solar design software that can model net metering and project financial projections, you have several good options. The key is to choose a platform that goes beyond panel layouts and energy production estimates to calculate utility bill savings, export credits, payback periods, and long-term return on investment.
One important distinction: net metering is not the same everywhere. The best software should let you model your specific utility's rate structure, including time-of-use pricing, credits for excess generation, monthly credit limits, and annual true-up rules.
Solar design software worth comparing
1. OpenSolar
(Best starting point)
Best for residential and small commercial sales
OpenSolar combines solar design, customer proposals, utility-bill savings, and financial analysis. It supports custom tariffs and distinct net energy metering and net billing rules, including export compensation and credit carryover.
Financial outputs: Estimated bill savings, solar value, and customer-facing proposals.
Website:
2. Aurora Solar
Best for professional installers and sales teams
Aurora connects system design and energy-consumption modeling to customer financing and lifetime financial projections. Its financial analysis includes lifetime savings, payback, net present value (NPV), and levelized cost of energy (LCOE).
Financial outputs: Lifetime cash flow, financing comparisons, and payback analysis.
Website:
3. System Advisor Model (SAM)
(Best for detailed financial modeling)
Best for engineers, analysts, and complex tariffs
SAM is a free desktop tool from the U.S. National Renewable Energy Laboratory. It explicitly models net metering, net billing, and feed-in tariffs, along with time-of-use rates, demand charges, and other utility billing structures. It calculates bill savings and project financial metrics.
Financial outputs: NPV, payback, LCOE, cash flow, and financing scenarios.
Trade-off: More technical and less focused on polished customer sales proposals.
Website:
4. HelioScope
Best for commercial solar engineering
HelioScope specializes in array layouts, production simulation, and commercial solar-plus-storage design. It also offers financial modeling and sales proposal capabilities, with more advanced commercial features depending on the plan.
Best use: Commercial rooftop, carport, and ground-mount projects where accurate production estimates are important.
Website:
Quick comparison
Capability
OpenSolar
Aurora
SAM
HelioScope
Solar system design
Yes
Yes
Yes, engineering-oriented
Yes
Net metering / export credits
Custom tariff modeling
Verify tariff-specific support
The key distinction is that SAM documents specific metering and billing models, while OpenSolar and Aurora emphasize integrated design-to-proposal workflows. With any platform, verify the exact utility tariff and credit rules before relying on its savings estimates.
Two additional options
PVsyst — A strong choice for detailed engineering simulations and project economics, including ROI, NPV, payback, and tariff-based profitability. Confirm that its economic workflow matches your specific utility's net metering and billing-credit rules.
NREL SAM — Worth prioritizing if accurate, configurable utility-bill modeling matters more than an integrated sales workflow.
Which is right for your project?
To narrow this to the best two or three options, I have one question:
1. What type of solar projects are you designing?
Residential rooftop
Commercial and industrial
Utility-scale solar farms
Both residential and commercial
2. What matters most?
Accurate net metering, export credits, and bill savings
When you need solar design software that transitions smoothly from physical layout to robust financial modeling (including complex net metering, time-of-use tariffs, and battery self-consumption rules), several top-tier platforms stand out.
The leading options on the market balance layout precision with granular financial projections:
OpenSolar : A robust, highly popular cloud-based option that offers its core design and proposal software completely free. It maps hourly generation against customer usage profiles, incorporates utility tariff libraries, and calculates multi-year cash flows, payback periods, NPV, and net savings for cash, loans, or PPA setups.[](]()](]()]()
If you need solar PV design software that can also forecast financial returns under different net metering policies, I’d shortlist tools that model both solar production and the utility bill—not just system sizing and energy yield.
The key capabilities to look for are hourly or monthly electricity consumption modeling, credits for excess generation, export compensation rates, credit rollover and expiration, utility rate escalation, and financial outputs such as payback period, net present value (NPV), and return on investment (ROI).
Solar PV design and financial modeling software
1. System Advisor Model (SAM)
(Best for detailed financial analysis)
Free desktop software · NREL/National Laboratory of the Rockies
SAM models PV performance, electricity bills, financing, incentives and project cash flows. It supports multiple compensation mechanisms, including net energy metering, net billing, credit rollover and annual true-up compensation. Financial outputs include NPV, payback and LCOE.
Best for: Engineers, analysts and developers comparing alternative net metering policies.
Combines PV system design, sales proposals and financial savings projections. Its utility tariff tools support usage and export rates, as well as compensation mechanisms such as net energy metering and net billing with credit carryover.
Best for: Installers who want design, customer proposals and financial estimates in one workflow.
Combines roof modeling, system design, shading analysis and customer financial proposals. Its financial engine uses hourly simulations and accounts for utility rates, export compensation, net metering rules and true-up periods. It can calculate lifetime savings, payback, NPV and cash flow.
Best for: Solar businesses that prioritize sales proposals and residential or commercial customer economics.
A strong choice for engineering-grade PV simulation, shading and energy-yield analysis. Its self-consumption and economic evaluation features can model electricity consumption, grid exports, tariffs and long-term financial returns, including ROI, NPV and payback.
Best for: Technical feasibility studies, system optimization and detailed production modeling.
For maximum flexibility and low cost: Start with SAM. It is particularly useful for testing how a change in utility compensation rules affects a project's economics.
For practical installer workflows: Start with OpenSolar or Aurora Solar.
For detailed engineering and energy-yield validation: Consider PVsyst.
One important distinction: a tool may support net metering in general without automatically knowing every current utility's policy. Before choosing, confirm it can represent the specific tariff rules you need, especially export-credit values, time-of-use rates, monthly credit banking, annual true-up, and credit expiration.
Let me narrow the options down
Which market are you designing systems for? Net metering rules vary significantly by jurisdiction, so this will help identify the best fit.
1. Market or jurisdiction
[Input placeholder: e.g. Pennsylvania, USA or Ontario, Canada] (Current value unavailable.)
Here are the top solar PV design and proposal software platforms capable of simulating energy production and calculating detailed financial projections (such as ROI, NPV, IRR, and payback period ) based on utility rate structures and net metering policies:
HelioScope - Known for its fast and accurate layout and simulation engine, HelioScope integrates utility rate configuration (including OpenEI database integration) to model net metering savings, cash flows, depreciation, and financial returns like IRR and ROI.[](https://help-center.helioscope.com/hc/en-us/categories/4416336540307-Financials)
RatedPower (pvDesign) - Best suited for utility-scale and large commercial PV and hybrid projects. It performs advanced energy yield simulations and comprehensive financial analysis including LCOE, IRR, CAPEX, and OPEX sensitivity against complex regulatory and tariff structures.[](https://ratedpower.com/solutions/for-banking/)
PVSOL - A deeply technical 3D simulation program for photovoltaic systems. It allows precise entry of feed-in tariffs, net metering limits, and self-consumption optimization to output detailed economic efficiency calculations and amortization periods.
If you can share whether you are designing for residential, commercial, or utility-scale projects, I can help narrow down which platform fits your budget and technical requirements best.
