NEM Version Comparison Calculator
Compare NEM 1.0, NEM 2.0, and NEM 3.0 solar savings side-by-side. Model payback, 25-year value, and battery ROI. Free, no signup required.
NEM Version Comparison Calculator
Select your NEM version and California utility. Compare export credit rates, self-consumption value, monthly bill impact, and see whether NEM 3.0 changes your solar ROI.
Export Earnings: NEM 1.0 = full retail rate. NEM 2.0 = retail minus non-bypassable charges (~$0.025/kWh). NEM 3.0 = ACC-based average ($0.05–$0.08/kWh).
Battery Model: Simplified single-cycle daily model - battery charges once from midday solar, discharges once in the evening. Capped at 95% max self-consumption.
25-Year Projection: Solar production declines at the selected degradation rate. Retail rates escalate at the selected annual rate. NEM 3 ACC export rates grow at 1%/yr.
Disclaimer: Educational estimates only. Actual savings depend on your specific tariff, TOU pricing, and usage patterns. Consult a licensed solar professional before making decisions.
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What This Tool Covers
California's shift from NEM 2.0 to NEM 3.0 (the Net Billing Tariff) cut export credit rates by roughly 75% for most utilities. This calculator quantifies exactly what that means for a specific system - comparing Year 1 bill impact, 25-year cumulative savings, and payback period across all three NEM generations. It also models battery storage as a self-consumption strategy under NEM 3.0.
NEM Version Inputs
Configure your system, utility, and rate assumptions to get a comparison tailored to your installation.
- System size (kW DC) and annual production (kWh)
- Utility selector: PG&E, SCE, SDG&E, or Other
- Retail rate, NEM 3 export rate, non-bypassable charges
- Self-consumption rate and battery storage size
- Annual rate escalation and panel degradation rate
- NEM 2.0 grandfathering PTO date (20-year protection clock)
Comparison Outputs
Side-by-side results across every NEM version - annual and 25-year - with battery impact broken out separately.
- Year 1 annual benefit per NEM version (self-consumption + export)
- 25-year cumulative savings trajectory with line chart
- Payback period comparison bars across all scenarios
- Battery impact card: additional annual savings and battery payback
- NEM 2.0 vs. NEM 3.0 annual dollar gap and self-consumption premium
Why Solar Professionals Use This Tool
California installers need a fast, credible answer to one question: "How much does NEM 3.0 cost my customer compared to NEM 2.0?" This calculator delivers that number alongside battery storage ROI - all in a shareable, client-ready format.
Three-Version Side-by-Side
NEM 1.0, NEM 2.0, and NEM 3.0 results rendered simultaneously. Customers see the generational value gap instantly - no spreadsheet required.
Battery ROI Modeling
Shows exactly how a Powerwall or similar system shifts exported kWh to self-consumed kWh under NEM 3.0 - with standalone battery payback period calculated separately.
Shareable URL Encoding
Every configuration is encoded into the URL. Send a customer a pre-filled link - they see their specific numbers without re-entering anything.
How It Works
Four inputs drive the entire comparison. The calculator handles the rate structure differences between each NEM version automatically.
Enter System Size and Location
Input your system size in kW DC. Select a production ratio preset for Northern, Central, or Southern California (or Desert SW), or enter annual kWh production directly from your PVWatts or design output.
Select Your Utility and Rate Structure
Choose PG&E, SCE, or SDG&E. The tool populates typical retail rates, ACC-based NEM 3.0 export rates, and non-bypassable charges. Override any value manually if you have the customer's actual bill data.
Set Self-Consumption Rate and Battery
Adjust the self-consumption slider (25–45% without battery, 65–90% with battery). Add battery storage capacity in kWh to model the NEM 3.0 + storage scenario alongside solo solar.
Set Financial Assumptions
Choose a rate escalation scenario (2.5%, 3.5%, or 5.0% annually) and panel degradation rate. Enter system and battery costs to calculate payback periods for each NEM scenario.
Review Results and Share
Instantly see Year 1 benefits, 25-year cumulative totals, and payback comparison bars across all NEM versions. Copy the URL to share a pre-filled version with your customer or colleague.
Built for Every Solar Professional
Sales Consultants
Walk customers through the NEM 2.0 vs. NEM 3.0 value gap in real time. The battery ROI card answers the "should I add storage?" question with a concrete payback number rather than a sales pitch.
Proposal Writers
Generate and share a pre-filled URL for each customer proposal. The comparison outputs align with what customers see in their utility statements, making the numbers credible and easy to verify.
NEM 2.0 Grandfathering Advisory
Existing NEM 2.0 customers nearing their 20-year grandfathering expiry can model what their bill looks like when they roll onto NEM 3.0 rates - and whether adding storage changes the outcome.
Calculation Methodology
The calculator separates solar value into two components - self-consumed kWh (offset at retail rate) and exported kWh (credited at the NEM-version-specific export rate). Battery storage shifts the split between these two pools.
Self-Consumption Savings
Savings = (Annual kWh × Self-Consumption %) × Retail Rate kWh consumed on-site avoid grid purchases at full retail rate. This value is identical across all NEM versions - the policy difference only affects exported kWh.
Export Credit (NEM 2.0 vs. NEM 3.0)
Export Credit = Exported kWh × Export Rate − (Exported kWh × NBC) NEM 2.0 credits exports at full retail rate. NEM 3.0 credits exports at ACC-based avoided-cost rates (roughly $0.05–$0.08/kWh) minus the non-bypassable charge (~$0.025/kWh).
Battery Self-Consumption Uplift
New SC% = min(Base SC% + Battery Uplift%, 95%) A single daily charge/discharge cycle shifts daytime export into evening self-consumption. The model caps self-consumption at 95% to reflect real-world mismatch between production and load timing.
25-Year Projection
Year N Savings = Year 1 × (1 − Degradation)^N × (1 + Escalation)^N Annual production declines at the selected degradation rate while retail rates escalate annually. NEM 3.0 export rates grow at approximately 1% per year per CPUC assumptions.
Pro Tips for NEM Comparison Analysis
Use the Customer's Actual Bill Rate
SDG&E customers often pay $0.45–$0.55/kWh on tiered rates - far above the state average. Entering the real rate from the bill dramatically changes the self-consumption savings figure and makes the proposal more defensible.
Model Battery Before Upsizing the Array
Under NEM 3.0, adding more panels mostly increases low-value exports. Adding a battery to an appropriately sized system often delivers better 25-year ROI than adding extra panels - the battery card shows this directly.
Check the NEM 2.0 Grandfathering Clock
NEM 2.0 customers who received PTO before April 2023 are protected for 20 years. Enter their PTO date to show exactly when their grandfathering expires - and what the bill looks like after that date at current NEM 3.0 rates.
Use 3.5% Rate Escalation as the Base Case
California utilities have averaged 3–5% annual rate increases over the past decade. The moderate 3.5% preset is the most defensible assumption for customer-facing proposals. Show the conservative and aggressive scenarios as a range.
Frequently Asked Questions
What is the difference between NEM 2.0 and NEM 3.0 in California?
NEM 2.0 credits exported solar at full retail rate (minus a small non-bypassable charge), so every kWh sent to the grid offsets a kWh you would have bought. NEM 3.0 (the Net Billing Tariff) replaces that with avoided-cost rates - roughly $0.05–$0.08/kWh depending on your utility and time of export - a reduction of about 75% compared to NEM 2.0 export credits. Self-consumed solar is valued identically under both programs.
Am I still eligible for NEM 2.0 in 2026?
New installations as of April 15, 2023 onward are enrolled in NEM 3.0 (Net Billing Tariff). If you received Permission to Operate (PTO) before that date, you are grandfathered on NEM 2.0 for 20 years from your PTO date. Customers who installed in early 2023 and rushed to get PTO before the deadline are protected until roughly 2043. This calculator lets you enter your PTO date to see exactly when grandfathering expires.
Does adding a battery make NEM 3.0 financially comparable to NEM 2.0?
For many systems it narrows the gap significantly but doesn't fully close it. A 10–13.5 kWh battery can raise self-consumption from around 35% to 70–80%, which recovers much of the lost export credit value. Whether NEM 3.0 + storage matches NEM 2.0 solo depends on your system size, daily load profile, and local electricity rate. The calculator's battery impact card shows both the additional savings and the standalone battery payback so you can evaluate the economics directly.
What is the non-bypassable charge and does it apply to NEM 2.0?
Yes. The non-bypassable charge (NBC) applies under both NEM 2.0 and NEM 3.0. It is deducted from export credits at approximately $0.025/kWh for PG&E and SCE customers, and higher for SDG&E. Under NEM 2.0, with export rates at $0.30–$0.50/kWh, the NBC is a minor deduction. Under NEM 3.0, with export rates of $0.05–$0.08/kWh, the NBC becomes a much more significant portion of the credit - in some cases consuming 30–50% of the export payment.
How accurate are these estimates?
The calculator uses simplified annual models rather than hour-by-hour TOU simulation. It is designed for directional accuracy - showing relative differences between NEM versions and the battery uplift - rather than billing-exact precision. Actual results vary based on your TOU rate schedule, monthly usage patterns, and how production and consumption align each hour. Treat the outputs as planning estimates and validate against your utility's bill calculator or a detailed energy model before finalizing a proposal.
Which utilities does this calculator support?
The calculator includes presets for PG&E, SCE, and SDG&E - the three California IOUs that fall under CPUC's NEM tariff rules. An "Other" option lets you manually enter retail and export rates for smaller utilities, community choice aggregators (CCAs), or out-of-state comparisons. Municipal utilities in California (LADWP, SMUD, etc.) operate under their own net metering rules and may not match the NEM 2.0/3.0 framework exactly.
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