350W panel preset
Solar Calculator for 350 Watt Panels
Start with 350W panels pre-filled, then adjust usage, state, shade, and offset for your home.
Use this preset when a quote lists lower-wattage modules and you want to see how panel count and roof space increase for the same target.
Estimate preview
Panels, cost, savings
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Estimate solar with 350W panels
Enter monthly kWh or electric bill. The calculator uses state-level assumptions and shows the math behind the result.
Your estimate
Example resultYou likely need 21-25 panels
Estimated system size: 7.8 kW. This is an estimate, not an installer quote.
Confidence
Medium
Planning estimate only — not an installer quote, engineering design, or tax advice.
Payback uses gross system cost before verified incentives, financing fees, batteries, and roof work.
- Estimated system size
- 7.8 kW
- Sized for your target offset and system loss assumption.
- Likely panel count
- 21-25
- Centered around 23 panels at 350W equivalent.
- Roof space
- 555 sq ft
- Includes a spacing factor, not a final layout plan.
- Annual production
- 10,800 kWh
- Modeled first-year output at the selected offset; not a production guarantee.
- Gross cost
- $18,445 - $23,939
- Before verified incentives, financing, or battery costs.
- Gross cost per watt
- $2.35 - $3.05
- Before incentives. Useful for comparing installer quotes.
- Annual savings
- $2,693
- Based on state residential rate and self-consumption assumption.
- Payback
- 6.8 years - 8.9 years
- Simple gross-cost payback estimate.
Annual usage: 10,800 kWh
Annual production target: 10,800 kWh
State rate: 35.25 cents/kWh
Export assumption: Partial export credit
Direct solar use: 5,940 kWh
Modeled exports: 4,860 kWh
Panel count view
21-25 panels
Estimate shape
Production, savings, and payback
Privacy note: the printable report link stores estimate inputs in the URL, including ZIP and usage or bill values. Keep it private if those details are sensitive.
Local scenarios
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Assumptions behind this estimate
- California state-level electricity rate and solar production defaults are used.
- 100% bill offset target.
- 350W solar panels.
- 14% system loss assumption.
- Roof area uses about 21 sq ft per panel plus spacing factor.
- Gross cost range excludes verified incentives, financing, batteries, roof work, and panel upgrades.
- 55% of annual solar production is modeled as directly used before export.
- Export value assumption: Partial export credit.
- Savings are energy-only and exclude fixed charges, minimum bills, demand charges, and time-of-use detail.
- You provided monthly kWh usage.
- State production defaults are used for this estimate.
Confidence drivers
- Overall confidence: Medium.
- You provided monthly kWh usage.
- State production defaults are used for this estimate.
Expected production: 10,800 kWh
System loss: 14%
Export value: Partial export credit
Direct solar use: 5,940 kWh
Modeled exports: 4,860 kWh
State production default: 1,600 kWh/kW/year
SolarCalcNow provides planning estimates only. Results are not installer quotes, engineering designs, tax advice, financing recommendations, or utility interconnection approval.
Optional next step
Want installer quotes based on this estimate?
Your estimate stays visible. This form is optional and uses explicit consent.
Installer quote matching is not active yet. You can still calculate, save, and print your estimate before contacting installers directly.
SolarCalcNow provides planning estimates only. Results are not installer quotes, engineering designs, tax advice, financing recommendations, or utility interconnection approval.
Real baseline
What the calculator returns for 900 kWh/month
Same inputs, different state data: 350 W panels, 900 kWh/month, low shade, 100% offset target, partial export credit, and no ZIP-level PVWatts override. This makes the state-rate and production assumptions visible before a quote.
| State | System | Panels | Gross cost | Payback |
|---|---|---|---|---|
| California | 7.8 kW | 21-25 | $18,445-$23,939 | 6.8 years-8.9 years |
| Texas | 8.4 kW | 22-26 | $19,674-$25,953 | 15.2 years-20.0 years |
| Massachusetts | 10.0 kW | 27-31 | $27,628-$36,670 | 12.3 years-16.3 years |
350W panels are still common on older quotes and compact roof layouts. Fewer watts per module usually means more panels for the same system kW, which can affect roof area and layout complexity.
Compare 350W against 400W or 450W on the same usage and state before accepting an installer panel count. Equipment availability varies by region and brand.
Compare planning presets
Same calculator engine with a different starting assumption. Useful before comparing installer quotes.
Monthly usage presets
Panel wattage presets
State calculators
Start with local assumptions
FAQ
Common solar calculator questions
When are 350W panels still used?
Some installers still propose 350W-class modules on tight roofs, legacy designs, or when higher-wattage inventory is limited. Always confirm the exact model on the quote.
Does panel wattage change payback?
Wattage mainly changes panel count and layout. Payback still depends on gross installed cost, production, and utility rules — not wattage alone.
Should I compare other wattages?
Yes. Run the same usage with 400W and 450W presets to see how panel count and roof space shift before comparing installer proposals.
What to do next
After calculating, save the estimate assumptions, check incentive status, and compare installer quotes against the same baseline.