Solar panels in Franklin, TN
Roofs in Franklin get about 1,539 hours of usable sunlight a year — more than 56% of the cities we've measured. Here's what that means in cost, savings and payback, using real rooftop data rather than a national average.
Check your specific roof in Franklin → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Franklin solar system costs
A 21-panel system (8.4 kW) is about right for an average Franklin home using 10,800 kWh a year. It would produce roughly 10,988 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 4,186 | $6,384 | $507 | 12.6 yrs |
| 12 panels | 4.8 kW | 6,279 | $9,576 | $760 | 12.6 yrs |
| 16 panels | 6.4 kW | 8,372 | $12,768 | $1,013 | 12.6 yrs |
| 20 panels | 8 kW | 10,465 | $15,960 | $1,266 | 12.6 yrs |
| 26 panels | 10.4 kW | 13,605 | $20,748 | $1,392 | 14.9 yrs |
How we worked this out for Franklin
Every number on this page comes from these seven steps. Nothing is a national average — the sunlight figure is measured from Franklin rooftops.
| # | Step | Result |
|---|---|---|
| 1 | What one panel makes here 400W ÷ 1000 × 1,539 sun hrs × 0.85 system losses |
523 kWh/yr |
| 2 | Panels needed to cover typical usage 10,800 kWh ÷ 523 kWh per panel |
21 panels |
| 3 | System size 21 panels × 400W |
8.40 kW |
| 4 | Annual production 8.40 kW × 1,539 hrs × 0.85 |
10,988 kWh/yr |
| 5 | Installed cost 8,400 W × $2.85 per watt, then −30% federal credit |
$16,758 |
| 6 | Annual saving 3,780 kWh used as generated × 12.1¢ + 7,208 kWh exported × 12.1¢ |
$1,313/yr |
| 7 | Payback $16,758 ÷ $1,313 per year |
12.8 years |
Step 6 matters more than it looks. Only 34% of what a system this size produces in Franklin is used the moment it is generated; the other 7,208 kWh is exported and credited one-for-one under net metering. Because exports here are credited at or near retail, that split changes the payback very little — 12.6 years against the 12.8 we show. In places where exports pay a fraction of retail the same split moves payback by years, which is why we model it explicitly rather than assuming.
Assumptions: 400W panels, 15% system losses (inverter, wiring, heat, soiling), $2.85/W installed, 10,800 kWh typical annual household use, 12.1¢/kWh electricity. Change any of those and every figure above moves — which is exactly why a single national "solar costs X" number is misleading.
Notice that payback barely improves as systems get bigger, and eventually gets worse. That's because you can only save money on electricity you were going to buy anyway. Once a system covers your usage, extra panels mostly generate exports at a much lower rate.
Why Franklin gets 1,539 sun hours
That figure comes from Google's analysis of real rooftops across Franklin — it already accounts for shading from trees, chimneys and neighbouring buildings, which is why it's lower than the raw "hours of daylight" figures you'll see elsewhere. An unusually open, unshaded roof in Franklin reaches about 1,618 hours, roughly 5% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,539 hrs/yr |
|---|---|
| Unshaded roof | 1,618 hrs/yr |
| Electricity rate (Tennessee avg) | 12.1¢/kWh |
| Installed cost assumed | $2.85/W |
| Panel size assumed | 400 W |
| Federal tax credit | 30% |
| Typical household usage | 10,800 kWh/yr |
| Power used as generated | 34% |
| Paid for exported power | full retail (net metering) |
| Rooftops sampled here | 14 |
| Google imagery from | 2015 |
When Franklin actually produces
Annual totals hide the thing that catches people out: 34% of Franklin's yearly sunlight arrives in May–July, and just 15% across November–January.
| Month | Sun hrs | Share of year |
|---|---|---|
| Jan | 77 | |
| Feb | 99 | |
| Mar | 126 | |
| Apr | 154 | |
| May | 173 | |
| Jun | 180 | |
| Jul | 176 | |
| Aug | 161 | |
| Sep | 136 | |
| Oct | 107 | |
| Nov | 82 | |
| Dec | 70 |
Franklin produces about 2.6× as much in Jun as in Dec — a normal mid-latitude swing. Expect real winter shortfall and summer surplus rather than steady year-round output.
The annual total is measured from Google's rooftop imagery. Its split across months is calculated from solar geometry at Franklin's latitude, not separately measured, so treat the monthly figures as the shape of a typical year rather than a forecast.
How Franklin compares to the other 788 cities
| Measure | Franklin | Rank of 788 |
|---|---|---|
| Usable sunlight | 1,539 hrs | 347th |
| Sunlight lost to shade | 5% | 415th most |
| Median roof size | 335 m² | 73rd largest |
| Electricity rate | 12.1¢ | 710th highest |
| Payback | 12.8 yrs | 632nd fastest |
| Grid carbon | 802 kg/MWh | 146th dirtiest |
What actually stands out about Franklin:
- Plenty of roof to work with. Typical roofs here fit around 101 panels — roughly 4× what an average home needs. Roof size will not be what limits your system in Franklin.
- Large roofs. At a median of 335 m², Franklin has the 73rd-largest typical roof footprint we've measured.
- Cheap electricity is the headwind. Tennessee power costs about 12.1¢/kWh. Low rates are good news generally, but they lengthen solar payback — there is simply less bill to displace.
- Older imagery. Google's aerial capture of Franklin dates from 2015. Tree growth and new construction since then are not reflected.
Cities with almost the same sunlight
These are the closest matches to Franklin's 1,539 usable sun hours from other states and provinces. Same sunlight, different electricity prices — which is usually what decides whether solar is worth it.
| City | Sun hrs | Rate | Payback |
|---|---|---|---|
| Norfolk, VA | 1,539 | 14.2¢ | 10.9 yrs |
| Chapel Hill, NC | 1,539 | 13.2¢ | 11.7 yrs |
| Alpharetta, GA | 1,538 | 14.1¢ | 11 yrs |
| Joliet, IL | 1,538 | 16.3¢ | 9.5 yrs |
Nearby cities
See all of Tennessee → statewide sunlight, rates, incentives and every city we've measured.
Franklin solar questions
How many solar panels do I need in Franklin?
About 21 panels for an average home using 10,800 kWh a year. Franklin roofs get 1,539 usable sun hours, so each 400W panel produces roughly 523 kWh annually. A typical Franklin roof fits about 101 panels, so roof space is unlikely to be your limit.
Is solar worth it in Franklin?
At 12.1¢/kWh and 1,539 sun hours, a typical system pays for itself in about 12.8 years and returns roughly $16,055 over a 25-year panel life. That is slower than average, so compare several quotes before committing. Exported power earns full retail credit here.
How much do solar panels cost in Franklin?
A 8.4 kW system costs about $23,940 before incentives and $16,758 after the 30% federal tax credit. That works out near $2.85 per watt installed. Roof pitch, shading, electrical panel upgrades and equipment choice move the price most, which is why quotes for the same house can differ by thousands.
Worth reading before you buy
Estimates only, generated 2026-08-22 from Google Solar API rooftop samples and average Tennessee electricity rates. Not a quote and not financial advice. Your roof, usage, utility plan and local incentives will change these numbers — get real quotes before buying.