Solar Data Source
MySolarROI uses homeowner-provided inputs, public data references, and transparent assumptions to help estimate solar costs, bill savings, payback period, incentives, financing impact, and long-term ROI.This page explains the main solar data sources that may be used or referenced when building solar estimates, what each source helps verify, and where homeowners should check current information before making a decision.
Solar results are never one-size-fits-all. Your actual numbers depend on your location, electricity rate, utility rules, roof conditions, system design, installer pricing, incentives, financing terms, tax situation, battery choices, and future electricity usage.
Use this page as a transparency guide. Then verify your own assumptions with your utility bill, installer quote, local utility, official incentive sources, and qualified professionals when needed.
Start with the MySolarROI solar ROI calculator to estimate solar savings, payback period, and long-term return using your own assumptions.
What Data MySolarROI Uses
MySolarROI estimates are built around the practical inputs that affect solar savings and ROI for homeowners.
| Data Type | Why It Matters | Best Source |
|---|---|---|
| Monthly electric bill | Helps estimate current energy spending and potential bill savings | Your utility bill or online utility account |
| Annual electricity usage | Helps size the system and estimate offset | 12 months of kWh usage from your utility |
| Electricity rate | Higher rates may increase solar savings; lower rates may lengthen payback | Your utility bill or rate tariff |
| Location | Affects sunlight, production, incentives, utility rules, and labor costs | Your address, ZIP code, or project location |
| System size | Determines estimated production, cost, savings, and payback | Installer quote or solar sizing estimate |
| Installed system cost | One of the biggest drivers of solar ROI | Written installer quote |
| Cost per watt | Helps compare quotes of different sizes | Gross cost divided by system watts |
| Solar production | Determines how much electricity the system may generate | Installer model, NREL PVWatts, or production estimate |
| Incentives and rebates | May reduce net system cost if you qualify | IRS, DSIRE, state energy office, local utility |
| Net metering or export credits | Determines how excess solar electricity is valued | Your local utility tariff |
| Financing terms | Interest, fees, lease payments, or PPA rates can change ROI | Lender, installer, lease, or PPA contract |
| Battery storage | Can add backup value but also increases cost | Battery quote, utility program, equipment specs |
Homeowner-Provided Inputs
The most important data often comes from the homeowner.
Your own utility bill, roof details, project goals, and quote information are usually more useful than national averages.
| Homeowner Input | Why It Improves the Estimate |
|---|---|
| 12 months of kWh usage | Shows actual annual electricity consumption |
| Current electricity rate | Shows the value of avoided grid electricity |
| Monthly bill amount | Helps estimate current spending and possible cash-flow impact |
| Solar quote price | Provides real project cost instead of a broad average |
| System size in kW | Helps estimate production, panel count, and cost per watt |
| Financing terms | Shows the effect of interest, fees, and total repayment |
| Battery quote | Helps separate solar-only and solar-plus-battery economics |
| Expected future loads | EV charging, heat pumps, or pool pumps may change system size |
If you do not have complete data yet, you can still use planning assumptions. Once you receive real quotes or utility information, update your estimate.
NREL PVWatts and Solar Production Data
Solar production is one of the most important assumptions in any solar savings or ROI estimate.
MySolarROI may reference or encourage comparison with NREL PVWatts because PVWatts estimates the energy production of grid-connected photovoltaic systems based on location and system inputs.
PVWatts can help estimate:
- annual solar production
- monthly production patterns
- the effect of system size
- the effect of tilt and azimuth
- the effect of system losses
- production differences by location
| PVWatts Input | Why It Matters |
|---|---|
| Location | Solar resource and weather vary by area |
| System size | Larger systems generally produce more electricity |
| Tilt | Panel angle affects annual and seasonal production |
| Azimuth | Panel direction affects production timing and output |
| System losses | Real-world losses reduce usable output |
| Array type | Roof mount, open rack, and tracking systems perform differently |
PVWatts is useful for production estimates, but it does not fully determine your electric bill savings, financing impact, tax eligibility, or solar ROI.
For a practical walkthrough, read the PVWatts calculator guide.
Electricity Rate and Utility Bill Data
Electricity rates strongly affect solar savings.
If you pay a higher rate per kWh, each kWh of solar electricity may be more valuable. If your rate is low, the same solar production may save less money.
The best source is usually your own utility bill because it reflects your actual rate plan, usage, and charges.
| Electricity Data | Best Source | Why It Matters |
|---|---|---|
| Annual usage | Utility bill or utility account | Helps size the solar system |
| Effective electricity rate | Utility bill | Helps estimate avoided cost |
| Fixed charges | Utility bill | May remain after solar |
| Time-of-use rates | Utility tariff | Can change value by time of day |
| Minimum bills | Utility tariff | Can limit bill reduction |
| Export credit rate | Utility solar tariff | Determines value of excess solar sent to grid |
Public sources such as EIA can provide state or national electricity data for context, but your own bill is usually more accurate for personal savings estimates.
For savings methodology, read the solar savings calculator guide.
Solar Cost Data
Solar cost is one of the biggest drivers of payback period and ROI.
MySolarROI estimates may reference broad cost benchmarks for planning, but real project cost should always come from written installer quotes.
Solar cost can include:
- solar panels
- inverter or microinverters
- racking and mounting hardware
- design and engineering
- installation labor
- permitting
- interconnection
- electrical work
- monitoring
- main panel upgrades
- roof work
- battery storage
- sales, overhead, and installer margin
| Cost Source | What It Helps With | Limitation |
|---|---|---|
| Installer quote | Best source for project-specific cost | Must compare what is included and excluded |
| Cost per watt | Helps compare quotes of different system sizes | Does not show equipment quality or add-ons |
| DOE/NREL benchmarks | Useful market context | Not a local quote |
| SEIA market data | Useful industry context | Not specific to your roof or utility |
For cost methodology, read the solar cost calculator guide.
Incentive and Tax Credit Data
Incentives can reduce net solar cost, but they must be verified.
MySolarROI may reference or encourage users to check:
- IRS guidance
- DSIRE
- state energy offices
- local government programs
- utility rebate pages
- battery incentive programs
- program application rules
| Incentive Source | What It Helps Verify |
|---|---|
| IRS | Federal tax credit rules and forms |
| DSIRE | State, local, and utility renewable energy incentives |
| State energy office | State-level program details |
| Local utility | Utility rebates, export credits, and interconnection rules |
| Local government | City or county solar programs |
| Tax professional | Personal tax eligibility and filing questions |
For new 2026 residential projects, homeowners should be careful with federal residential tax credit assumptions. Do not automatically include old federal credit assumptions without checking current IRS guidance and personal eligibility.
For details, read the federal solar tax credit 2026 guide and the solar tax credit calculator guide.
Net Metering and Utility Rule Data
Net metering, net billing, and solar buyback rules affect how excess solar electricity is valued.
These rules can vary by state, utility, tariff, system size, customer class, and installation date.
| Utility Rule | Why It Matters |
|---|---|
| Full retail net metering | May increase savings if exported solar is credited near retail value |
| Net billing | Requires separate import and export rate assumptions |
| Avoided cost credit | May reduce the value of exported solar |
| Time-of-use rates | Production timing can affect savings |
| Fixed charges | May remain after solar |
| Annual true-up rules | Determine how unused credits are handled |
The best source for this information is your local utility’s current solar tariff or rate schedule.
For a homeowner-friendly explanation, read the net metering explained guide.
Financing Data
Financing can significantly affect solar ROI.
MySolarROI estimates may consider cash purchase, solar loans, leases, and PPAs, but the final terms must come from written financing documents.
| Financing Data | Why It Matters |
|---|---|
| Cash price | Shows base system cost without loan structure |
| Financed price | Shows whether financing increases cost |
| APR | Affects interest and monthly payment |
| Loan term | Affects payment size and total repayment |
| Dealer fee | May be included in financed price |
| Lease payment | Affects monthly cash flow |
| PPA rate | Determines cost of solar electricity purchased under contract |
| Escalator | Can increase lease or PPA payments over time |
| Home sale terms | May affect transfer, payoff, or buyout |
For financing comparisons, read the solar financing comparison guide, the solar loan calculator guide, and the solar lease vs PPA guide.
Battery Storage Data
Battery storage can add backup value, but it also increases project cost.
Battery estimates should consider:
- installed battery cost
- usable capacity
- power rating
- backup configuration
- critical loads
- time-of-use savings
- low export credit value
- utility battery incentives
- warranty and degradation
- replacement assumptions
| Battery Data | Why It Matters |
|---|---|
| Usable kWh | Shows how much energy is available |
| Power rating | Shows how much load the battery can support at once |
| Backup loads | Determines what runs during an outage |
| Installed cost | Determines financial impact |
| Incentives | May reduce net battery cost if available |
| Warranty | Affects long-term value and replacement risk |
For battery-specific analysis, read the solar battery ROI guide.
How Often Should Data Be Checked?
Solar data can change. Homeowners should verify key assumptions before signing a contract.
| Data Type | Why It Should Be Checked |
|---|---|
| Electricity rates | Utility rates can change over time |
| Net metering rules | Utilities and regulators can update solar tariffs |
| Incentives | Programs can expire, change, or run out of funding |
| Tax credit rules | Federal and state tax rules can change |
| Installer pricing | Local quote pricing varies by project and market |
| Financing terms | APR, dealer fees, and loan terms can change quickly |
| Battery programs | Utility battery programs may open, close, or revise terms |
Always verify current information with official sources, written quotes, and current contract documents.
What MySolarROI Does Not Guarantee
MySolarROI is an educational calculator, not a guarantee.
It does not guarantee:
- actual solar savings
- actual payback period
- actual ROI
- tax credit eligibility
- incentive approval
- installer pricing
- solar production
- utility bill outcomes
- net metering treatment
- financing approval
- home value increase
- battery backup duration
Use the calculator to understand the math and compare scenarios. Use official sources and professional advice to verify final decisions.
Recommended Verification Checklist
Before signing a solar contract, verify these items:
- 12 months of electricity usage from your utility bill
- current electricity rate and rate plan
- system size in kW
- gross installed cost
- cash price and financed price
- cost per watt
- annual production estimate
- shade and roof assumptions
- utility net metering or export credit rules
- incentives and eligibility
- loan, lease, or PPA terms
- battery cost and backup limits
- roof or electrical work included in the quote
- warranty and maintenance terms
For quote review, use the solar quote comparison checklist.
External Sources to Check
Use these sources to verify solar assumptions before making a decision:
- NREL PVWatts Calculator
- NREL solar resource and renewable data
- U.S. Department of Energy homeowner solar guide
- EIA electricity data
- DSIRE incentive and policy database
- IRS Residential Clean Energy Credit guidance
- FTC solar consumer guidance
- CFPB solar financing research
- Your state energy office
- Your local utility’s current rate plan, interconnection rules, and solar export tariff
FAQ About Solar Data Sources
What data sources does MySolarROI use?
MySolarROI uses homeowner-provided inputs, public electricity data references, solar production tools, incentive resources, utility rule assumptions, financing inputs, and transparent financial formulas to estimate solar cost, savings, payback, and ROI.
Is MySolarROI connected to my utility bill?
No, not automatically. Homeowners should enter their actual bill details when possible. Your own utility bill is usually more accurate than a state or national average.
Where does solar production data come from?
Solar production estimates may reference tools such as NREL PVWatts, solar resource data, installer production models, and user-entered assumptions such as system size, tilt, azimuth, and losses.
Where does incentive data come from?
Incentive information should be checked against IRS guidance, DSIRE, state energy offices, local governments, and utility program pages. Incentives can change, so homeowners should confirm eligibility before signing.
Does MySolarROI guarantee my solar savings?
No. MySolarROI provides educational estimates. Actual savings depend on your utility rates, net metering rules, production, system cost, financing, roof conditions, incentives, and future energy use.
Should I use public averages or my own bill?
Your own utility bill is usually better. Public averages can help with early research, but your actual electricity usage, rate plan, and utility rules matter more.
How often should solar data be checked?
Electricity rates, incentives, utility rules, tax rules, and financing terms can change. Homeowners should verify the latest information before signing a contract.
Are installer quotes still necessary?
Yes. A calculator helps you understand the math, while installer quotes provide project-specific pricing, equipment, roof design, and financing details. Always compare multiple quotes.
Conclusion
The goal of this Solar Data Sources page is simple: show homeowners where MySolarROI estimates come from and what those numbers can and cannot tell you.
Solar calculators are most useful when the inputs are clear. Your electric bill, installer quote, local utility rules, incentive eligibility, production estimate, and financing terms all matter.
Use MySolarROI as a practical starting point. Then verify the details with your installer, utility, tax professional, and local program administrator before making a final solar decision.
Run your solar ROI estimate and compare conservative, base-case, and optimistic scenarios before reviewing installer quotes.