Introduction
Choosing between community solar and rooftop solar can be complex. This calculator helps you estimate and compare the
annual costs of subscribing to a community solar program versus owning a rooftop solar system.
Enter your electricity usage and cost assumptions to see which option is cheaper under the same usage.
Formulas Used in the Calculator
The calculator compares two main cost scenarios: community solar subscription costs and rooftop solar ownership costs.
Community Solar Annual Cost
This includes the cost per kilowatt-hour (kWh) charged by the community solar provider multiplied by your annual electricity usage,
plus any fixed annual subscription fees.
Rooftop Solar Annual Cost
This is calculated by spreading the initial rooftop installation cost over the system lifespan (annualized capital cost)
plus the annual maintenance cost.
Interpreting Results
The calculator outputs the estimated annual costs for both options. A lower annual cost suggests a more economical choice
based on your inputs. These estimates do not include potential tax credits, incentives, financing/interest, or changes in electricity rates.
Worked Example
Suppose you use 10,000 kWh annually. The community solar rate is $0.10/kWh with a $100 annual subscription fee.
Rooftop installation costs $15,000 with a 25-year lifespan and $200 annual maintenance.
- Community Solar Cost = (10,000 kWh × $0.10) + $100 = $1,000 + $100 = $1,100 per year
- Rooftop Solar Cost = ($15,000 ÷ 25 years) + $200 = $600 + $200 = $800 per year
In this example, rooftop solar has a lower annual cost, but other factors like upfront investment and maintenance responsibilities should be considered.
Comparison Table
Inputs and cost components used for community solar and rooftop solar annual cost comparison
| Cost Component |
Community Solar |
Rooftop Solar |
| Annual Electricity Usage (kWh) |
Input by user |
Input by user |
| Rate ($/kWh) |
Community Solar Rate |
Not applicable |
| Annual Subscription Fee ($) |
Subscription Fee |
Not applicable |
| Installation Cost ($) |
Not applicable |
Rooftop Install Cost |
| System Lifespan (years) |
Not applicable |
System Lifespan |
| Annual Maintenance Cost ($) |
Not applicable |
Annual Maintenance Cost |
| Estimated Annual Cost ($) |
CommunitySolarCost formula |
RooftopSolarCost formula |
Limitations and Assumptions
- The calculator assumes constant electricity usage and rates over the system lifespan.
- It does not account for potential incentives, tax credits, or changes in energy prices.
- Rooftop solar costs are annualized evenly over the lifespan; actual financing or loan costs are not included.
- Maintenance costs are estimated annually and may vary by system and location.
- Community solar subscription terms and availability vary by provider and region.
- The calculator does not consider environmental benefits or property value impacts.
Frequently Asked Questions
What is community solar?
Community solar allows multiple customers to subscribe to a shared solar power system, receiving credits on their electricity bills without installing panels on their property.
How does rooftop solar ownership work?
Rooftop solar involves installing solar panels on your property, generating electricity onsite, and potentially reducing your utility bills directly.
Can I combine community solar and rooftop solar?
In some cases, yes. Some customers subscribe to community solar while also having rooftop panels, but this depends on local regulations and utility policies.
Does this calculator include tax credits?
No, this calculator does not factor in tax credits or incentives. You should consider those separately when evaluating costs.
How accurate are the cost estimates?
Estimates depend on the accuracy of your inputs and assumptions. Actual costs may vary due to changes in rates, system performance, and other factors.
Can I use this calculator for commercial properties?
This calculator is designed for residential-scale usage. Commercial solar projects may have different cost structures and should be evaluated separately.
Why Compare Community and Rooftop Solar?
Rooftop solar has long been the gold standard for homeowners seeking lower energy bills and greener power. However, millions of people cannot install panels because they rent, live in shaded areas, or face structural limitations. Community solar subscriptions, which allocate a portion of a shared solar farm's production to a customer, have emerged as an alternative. Subscribers receive credits on their utility bills for the energy generated. They avoid upfront equipment costs but pay a per-kWh rate and often a small annual fee. This calculator puts community solar and rooftop ownership side by side so you can evaluate which path offers the lower annual cost for your specific usage.
The rise of community solar addresses equity concerns in renewable energy adoption. Renters, condo dwellers, and low-income households can participate without a roof. Utilities and third-party developers increasingly offer subscriptions with modest discounts below utility rates. Yet those savings might pale compared to the long-term benefits of owning panels if you have the means and suitable property. By quantifying both options, the tool helps households make informed decisions about joining a community solar program or investing in a rooftop system.
How the Calculation Works
The annual cost of community solar is straightforward: multiply your annual electricity usage by the subscription rate and add any annual administrative fee. Rooftop solar involves spreading the installation cost across the system's lifespan and adding expected annual maintenance like cleaning or inverter replacement reserves. The calculator assumes the rooftop system offsets your entire annual usage; if it generates less, real costs would include residual grid consumption. Results display each approach's annual cost and the difference between them, revealing the more economical choice over time.
The formula for annual rooftop solar cost r is:
r
=
I
L
+
M
Where is the installation cost, is system lifespan in years, and is annual maintenance cost.
Community solar annual cost s is:
s
=
U
×
R
+
F
Where is annual usage and is the community solar rate per kWh, with representing any subscription fee.
The difference displayed is s−Cr.
Worked Example (Alternative Scenario)
Imagine a household using 8,000 kWh annually. A community solar provider offers energy at $0.11 per kWh with a $20 yearly fee. The annual cost becomes 8,000 × $0.11 + $20 = $900. A rooftop system sized to meet the same demand costs $20,000 to install, is expected to last 25 years, and needs $200 per year in maintenance and inverter reserves. The annualized cost is $20,000 / 25 + $200 = $1,000. In this scenario, community solar appears cheaper by $100 per year. However, if installation costs drop to $15,000 or incentives reduce the net price, rooftop ownership could win over the long term. This demonstrates the importance of customizing assumptions for your situation.
Scenario Comparison
The first table explores how community solar rates influence annual costs for an 8,000 kWh household with a $20 fee.
Community solar annual cost at different subscription rates for 8,000 kWh usage and $20 fee
| Rate ($/kWh) |
Annual Community Cost ($) |
| 0.09 |
740.00 |
| 0.11 |
900.00 |
| 0.13 |
1,060.00 |
The second table varies rooftop installation cost while keeping lifespan at 25 years and maintenance at $200.
Rooftop solar annualized cost at different installation costs for 25-year lifespan and $200 maintenance
| Install Cost ($) |
Annual Rooftop Cost ($) |
| 15,000 |
800.00 |
| 20,000 |
1,000.00 |
| 25,000 |
1,200.00 |
Limitations and Assumptions (More Detail)
This calculator assumes your rooftop system offsets 100% of usage and ignores financing costs. Real installations may rely on loans with interest, or produce less than expected due to shading, orientation, or degradation. Maintenance costs are treated as a flat annual value though major component replacements may occur intermittently. Community solar contracts can include escalators, early termination fees, or credit rate variations tied to utility prices. The model does not account for tax credits, renewable energy certificates, or net metering payouts that can significantly change rooftop economics. Users should adjust inputs based on actual quotes and contract terms.
Environmental and community benefits are mentioned qualitatively. Community solar often supports local jobs and expands access to clean energy, while rooftop installations can increase property value and provide backup power when paired with batteries. Regulatory frameworks also vary widely by region, affecting interconnection costs and credit valuations. Therefore, treat the results as a starting point rather than a definitive financial plan.
Further Reading
To dive deeper into ownership economics, explore the solar roof payback calculator or compare hybrid solutions with the solar battery payback calculator. If you are evaluating other renewable options, the solar vs home wind system cost calculator offers additional context.
