SharePlane · SMUD Solar + Powerwall ROI
DealElectricalUsageRatesTOU ledgerCalculatorUnknownsSources
Sacramento residential energy stack analysis · self-contained model · no utility identifier included

SMUD solar, storage, and Powerwall decision model.

A single-page, interactive view of the proposed Powerwall 3 + Expansion, added 3.08 kW solar array, SMUD incentives, current bill profile, and realistic ROI range. Because apparently electricity bills needed a cockpit, a tax footnote, and a tiny warning siren.

Base-case read

Assuming the $13,415 net investment holds, the $880/year VPP credit is paid, and added solar produces about 3,900 kWh/year, the deal pencils out mainly because the battery incentive is strong and your house still imports a lot of energy.

8.9 yrs

Default interactive model, before assigning value to outage backup. Adjust assumptions below.

$13,415 net to recoup$880/year VPP credit3,800-4,000 kWh/year new solar27 kWh storage
Gross project economic value$34,415
SMUD enrollment incentive−$10,000
Tesla rebate−$1,000
Installer lease/tax-structure subsidy−$10,000
Long-term investment to recoup$13,415

The $10k installer subsidy is modeled as embedded in the net deal economics. It is not treated as a separately enforceable rebate because the lease/tax structure is intentionally sensitive. Human accounting, a haunted forest with decimals.

Project snapshot

What is being added, what is already on the roof, and what still needs confirmation before the handshake turns into paperwork.

Added PV array3.080 kW DC7 × Silfab 440W, 2.836 kW CEC AC
New storage27 kWhPowerwall 3 + Powerwall 3 DC Expansion
Existing Sunrun solar4,748 kWhActual generation over uploaded year
Verified VPP value$880/yr2-battery recurring credit, before tax

Confirmed economics

Powerwall 3 + Expansion qualifies for $880/year VPP.
SMUD lists Powerwall 3 with DC Expansion in the 2026 recurring incentive table.
Net long-term investment is modeled at $13,415.
This is the amount the household must economically recover over time.

Design facts

New panels are not optimally south-facing.
Plan orientation is split at 291° and 111° azimuth with 30° tilt, so the 3,800-4,000 kWh estimate is treated as realistic, not guaranteed.
Subpanel rating still needs final confirmation.
Preliminary drawing showed 125A. Sales statement said 200A.

Battery role

Backup + VPP + peak support.
Pure rate arbitrage is not the main value driver because your annual peak kWh is limited. The VPP credit is the anchor.
SMUD can control events.
SMUD says it leaves a 20% reserve and can dispatch during grid events.

Electrical capacity gate

This is the one remaining non-economic decision gate. A 200A subpanel is useful distribution hardware, but it does not create a second 200A utility service. The final answer lives in the load calculation, feeder/breaker sizing, and any load-management strategy. Copper wire continues to be rude about physics.

What the installer has represented

200A subpanel will be installed.
The installer says final plans will reflect the 200A panel, replacing the earlier preliminary 125A drawing mismatch.
Solar and batteries do not add household load.
Their electrical team correctly notes that PV and storage are power sources, not additional appliance demand. The issue is existing and future load, not the solar/storage hardware itself.
Preliminary load calc was about 171A on a 200A service.
That was represented as after the modeled EV charger placeholder. The question is whether the modeled assumptions match the actual home.

What still needs to be true

Actual HVAC and water-heater dataThe final load calculation should account for the actual 5-ton heat pump and electric water heater, not a stale 3-ton AC assumption or incomplete appliance list.
Future EV charging pathA future 40A charger may be fine. A future 60A-80A output charger likely needs load management or a SMUD service upgrade. That should be stated plainly.
High-load home electronicsServer/workstation loads are not always captured well by generic dwelling calculators. They may not dominate the formal NEC load calc, but they matter operationally for circuit planning.
Decision posture: the deal can still be financially attractive, but do not treat the new subpanel as new service capacity. Treat it as distribution/future-flexibility unless the final electrical design proves additional usable headroom.

Your last 12 SMUD bills

Billing period analyzed: June 10, 2025 through June 9, 2026. This is the macro-level reality check. Your house is a high-load site with useful room for more solar because current exports are small relative to total consumption.

Total household use21,189 kWhGross load before solar offsets
Imported from SMUD17,261 kWhStill grid-dependent even with current solar
Sent to SMUD820 kWhOnly 17.3% of current solar output
Annual SMUD charges$2,962Actual electric service charges paid

Annual energy flow

Existing solar supplied about 22.4% of gross household usage. Most of that solar was self-consumed, which is good. The new array should mostly offset imports, not merely flood SMUD with cheap export energy.

Monthly bill and usage trend

Bars = bill dollars. Line = gross household kWh. Summer plus EV plus HVAC is where civilization starts invoicing you for comfort.

Time-of-use exposure

The battery can help shift energy away from expensive periods, but your current peak exposure is not massive. The big guaranteed value remains the VPP payment.

Annual SMUD imports by TOD bucket

Interpretation

Peak imports
1,539 kWh
Non-peak imports
15,722 kWh

Only 8.9% of annual imported kWh landed in the 5-8 p.m. peak window. Weighted peak rate is about 26.1¢/kWh; weighted non-peak import rate is about 14.5¢/kWh. Even if every current peak kWh were shifted, the theoretical annual rate-arbitrage ceiling is only about $179/year.

That is why this model uses a modest battery optimization value, not fairy dust.

Summer off-peak15.50¢Midnight-noon, weekends/holidays
Summer mid-peak21.39¢Noon-5 p.m. and 8 p.m.-midnight
Summer peak37.65¢Weekdays 5-8 p.m.
Non-summer off-peak12.85¢Midnight-5 p.m. and 8 p.m.-midnight
Non-summer peak17.76¢Weekdays 5-8 p.m.
SSR export value9.60¢Credit for excess exported solar

Actual time-of-use ledger

This restores the nerdy part that actually matters: annual imported kWh by SMUD rate bucket, current rate, share of imports, and modeled charge exposure. This is why the battery is valuable, but not because of giant arbitrage.

TOU bucketAnnual imported kWhShare of grid importsRate usedModeled energy costInterpretation
Summer off-peak3,58020.7%15.50¢/kWh$555Large summer baseline bucket. More solar can offset this, but value is moderate.
Summer mid-peak1,85410.7%21.39¢/kWh$397Useful solar/battery target, especially afternoon and early evening shoulder load.
Summer peak6433.7%37.65¢/kWh$242Most expensive bucket, but not enough volume to carry the ROI alone.
Non-summer off-peak10,28859.6%12.85¢/kWh$1,322Dominant import bucket. New solar offsets some of this at a lower avoided value.
Non-summer peak8965.2%17.76¢/kWh$159Peak but comparatively mild. Battery helps, just not dramatically.
Total imports17,261100%Weighted avg 15.5¢/kWh$2,675Energy-only exposure before fixed charges, taxes, credits, and bill structure.
Peak import total1,539 kWh8.9% of annual imports
Peak-shift ceiling~$179/yrTheoretical spread value, not a guaranteed saving
Primary battery value$880/yrVPP payment remains the anchor

Interactive ROI calculator

Adjust the assumptions that actually matter. The defaults are deliberately conservative-ish: 3,900 kWh/year new solar, 90% self-use, 15.5¢ avoided import rate, $100/year incremental battery optimization, and a $47/year SSR export-value drag.

Year-1 benefit$0
Simple payback0 yrs
20-year NPV$0

Monthly source table

The boring table that keeps the pretty dashboard from becoming interpretive dance.

BillPeriodBill $Gross useFrom SMUDSolar genSent to SMUDNet billedEV credit kWh

Known unknowns and decision gates

These are not reasons to kill the deal. They are the last few places where sloppy language can turn a good project into future annoyance with a permit number.

Property encumbranceGet a clear answer on whether there is any lien, UCC filing, fixture filing, deed restriction, or other recorded encumbrance against the house/property.
Subpanel mismatchSales statement says 200A. Preliminary drawing showed 125A. Final plan set should show the actual installed panel and match the quote.
Lease/title transferThe post-5-year ownership transfer may not be fully documented because the tax/lease structure depends on third-party ownership. Treat any unwritten transfer promise as operational expectation, not guaranteed asset title.
VPP incentive durabilityThe 2026 payment is strong, but SMUD terms say recurring incentives may be adjusted annually and the program can change.
SSR transitionAdding battery storage with SMUD incentives can move solar customers to the Solar and Storage Rate. In your case the export-value loss looks modest because annual exports are low.
Tax treatmentSMUD says recurring incentives are taxable and reportable if over $600. Use the calculator tax haircut if you want after-tax payback.

Sources and calculation notes

Self-contained file, but not self-deluding. The model uses uploaded bills, uploaded plan documents, and public SMUD program/rate pages.

Uploaded documents used

  • SMUD bills from June 2025 through May 2026, extracted from the 12 uploaded PDF statements.
  • Project plan set dated 06/25/2026 showing the 3.080 kW DC / 2.836 kW AC PV addition, Tesla Powerwall 3 + DC Expansion, existing solar system, and preliminary electrical drawing.
  • The plan set's preliminary subpanel note showed 125A. Sales statement says 200A, so this remains a document-control gate.

Public program/rate references

Model principle: VPP income is treated as the anchor. Added solar savings are modeled conservatively. Battery optimization is deliberately modest because your current annual peak imports are limited.