New Solar System
I Already Have Solar
Battery Only
1
Location & Bills
We use this to find your roof on satellite, look up your utility rate, and pull local weather data.
$
Your highest bill from June to August. If blank, we estimate from your home size and local climate.
$
Your highest bill from December to February. A home heated by a heat pump often has its highest bill in winter, so enter both.
Auto-populated when you enter your address.
2
Your Roof
🗺
Enter your address above
Satellite view will load automatically, or enter roof details manually below.
Single face
Gable
Hip (4 faces)
Flat
Custom
Select your roof type. Gable = 2 slopes, Hip = 4 slopes.
25°
Most US homes are 20°–35°. Flat roofs are 0°–5°.
N
NE
E
SE
S
SW
W
NW
sq ft
Total roof area available. Fire code setbacks and pathways (~33%) will be deducted automatically.
None
Minimal (5%)
Moderate (15%)
Heavy (30%)
Severe (50%)
3
System Preferences
How much of your electric bill should solar cover?
Max roof space
Max consumption
100% of bill
75% of bill
50% of bill
Custom kW
The main breaker in your panel. It sets how much solar one panel can take back (NEC 705.12, the 120% rule).
Include home battery?
Stores excess solar for evening use and backup power.
Charging an EV at home?
Size your system to cover EV charging and see fuel savings.
kWh
Your last 12 months of use, from your bill or your utility's website, including any EV you already charge at home. It sets the yearly total; your bills still shape the months. An EV you add below is counted on top.
Microinverters
String + optimizers
String only
Microinverters work best with shading or multi-face roofs. String inverters cost less for simple layouts.
Compare inverters in resultsShow top inverter picks with scoring breakdown.
%/yr
Typical: 0.3–0.7%/yr. Premium panels degrade slower.
%
Includes wiring, soiling, mismatch, clipping. NREL default: 14%.
%
Leave blank to auto-calculate from weather data and roof pitch.
25 years
30 years
Asphalt shingles
Metal roof
Clay / concrete tile
Flat / rubber
Affects mounting hardware cost. Tile adds ~15%; metal saves ~5%.
Bifacial panels?
Panels that collect light on both sides. Best for flat/low-pitch roofs with light-colored surfaces.
%/yr
Historical average is ~2.5–3.5%/yr. Used for 25-year savings projections.
%/yr
Your alternative return, paying down a mortgage, or leaving it invested. Sets the net present value and the levelised cost, which say whether solar beats that alternative rather than just whether it eventually pays back.
%/yr
Annual erosion in export compensation. 0% assumes today's NEM rate holds for 25 years. Try 2–5% for a conservative estimate.
Include battery replacement in long-term analysis
Most lithium-ion batteries retain usable capacity for 15–25+ years depending on warranty class and cycling. Off by default; turn on for a conservative scenario that budgets for one replacement when expected capacity drops below 50%.
Monthly Solar Production vs. Grid Usage
Each month shows two stacked bars side by side: solar production split into self-consumed (green), exported to the grid (yellow) and, with a battery, its small round-trip loss (dark gray), next to the energy you still pulled from the grid (light gray). Where the utility buys all output, the production bar is what it bought.
Cumulative Savings Over Time
When your solar investment breaks even and total net benefit over the analysis period.
Financing Options
Set the loan and lease terms you have been quoted; the comparison below updates as you type.
%
10 yr
15 yr
20 yr
25 yr
$/kWh
%/yr