Solar Decision Guide
Homeowner Summary
Solar energy has reached a tipping point: in most of the United States, a properly sized solar system produces electricity cheaper than buying it from the utility. With the 30% federal Investment Tax Credit (ITC) available through 2032, the financial case has never been stronger. But solar is not right for every home, and the details matter enormously — a poorly designed system or a bad financing agreement can turn a great investment into a mediocre one.
The key questions are: Is your roof suitable? Are your utility rates high enough to make the math work? What is the best way to pay for it (buy, lease, or PPA)? Do you need battery storage? This guide provides a structured framework for answering each question with confidence.
The short version: if you have a south-facing (or east/west-facing) roof with minimal shading and at least 10 years of life remaining, and your electricity rate is above $0.12/kWh, solar almost certainly makes financial sense as a purchased system. If your rate is above $0.15/kWh, it is a strong investment. Above $0.20/kWh (California, Northeast, Hawaii), it is exceptional.
How It Works
Solar Photovoltaic (PV) Basics: Solar panels convert sunlight into direct current (DC) electricity. An inverter converts DC to alternating current (AC) that your home uses. When the panels produce more than you consume, the excess flows to the grid. When you consume more than the panels produce (night, cloudy days), you draw from the grid. A net meter tracks the flow in both directions.
Net Metering: Under net metering, the utility credits you for excess electricity you export to the grid at or near the retail rate. At the end of each billing period, you pay only for the "net" electricity consumed. This effectively makes the grid your battery — export during the day, draw at night. Net metering policies vary significantly by state and utility.
Battery Storage: A home battery (like Tesla Powerwall, Enphase IQ, or Generac PWRcell) stores excess solar production for use after sunset, during power outages, or during peak-rate hours. Batteries add $10,000-$15,000 to the system cost but provide energy independence, backup power, and peak-rate avoidance. Whether a battery makes financial sense depends on your net metering policy and outage risk.
Maintenance Guide
DIY (Homeowner)
- Visual inspection of panels quarterly: look for physical damage, bird nests, heavy soiling
- Monitor production monthly via the inverter app or monitoring platform — a sudden drop indicates an issue
- Clean panels 1-2 times per year if production drops more than 5% (garden hose, soft brush; avoid harsh chemicals or pressure washers)
- Keep trees trimmed to prevent new shading
- Check the inverter display for error codes or warning lights periodically
- Verify the electric bill reflects net-metering credits
Professional
- Annual inspection: check panel mounting hardware, wiring connections, conduit integrity
- Inverter inspection: verify efficiency, check for overheating signs, test rapid shutdown
- String inverter replacement planning: budget for replacement at year 10-15 (micro-inverters last 20-25 years)
- Battery system maintenance: annual health check, firmware updates, capacity test
Warning Signs
- Production drops more than 10% compared to the same month last year (panel soiling, inverter issue, or new shading)
- Inverter shows error codes or flashing red/yellow lights
- Electric bill spikes despite solar (system may be offline without your knowledge — check the monitoring app)
- Visible damage to panels (hail, wind-blown debris, cracking)
- Roof leak near panel mounting points (flashing or sealant failure)
- Battery capacity decreasing noticeably (more than 20% degradation in the first 5 years is abnormal)
- Utility changes net metering policy (check annually — this affects ROI going forward)
When to Replace vs Repair
- Panels: 25-year manufacturer warranty is standard; panels degrade approximately 0.5% per year. At year 25, a panel is still producing 87%+ of original capacity. Replacement is rarely needed; repair individual panels only if physically damaged
- String inverter: 10-15 year lifespan. Plan for one replacement during the system's life ($1,500-$3,000). This is a known cost — include it in your ROI calculation
- Micro-inverters: 20-25 year lifespan with 25-year warranties from Enphase and others. Rarely need replacement
- Battery: 10-15 year lifespan with 70-80% capacity warranty. Replace when capacity drops below usable levels (typically 60-70% of original)
- Mounting hardware: Inspect at year 15-20. Corrosion on aluminum rails or degraded flashing may need repair
Pro Detail
Specifications & Sizing
Roof Assessment Checklist:
| Factor | Ideal | Acceptable | Not Recommended |
|---|---|---|---|
| Orientation | True south (180°) | SE to SW (135°-225°) | North-facing (loses 20-30%) |
| Roof pitch | 20-40 degrees | 10-50 degrees | Flat (needs tilt racks) or >50° |
| Shading | None (0% shade) | <10% shade 9AM-3PM | >25% shade during peak hours |
| Roof age | New or <5 years old | 5-15 years old | >15 years (replace roof first) |
| Roof condition | No damage, good drainage | Minor wear, repairable | Active leaks, structural concerns |
| Roof material | Composite shingle, metal | Tile (with special mounts) | Cedar shake, slate (fragile, expensive to mount) |
| Available area | 300+ sq ft unshaded | 200-300 sq ft | <200 sq ft (insufficient for meaningful system) |
System Sizing:
| Annual Electric Usage | System Size | Panel Count (400W) | Roof Area Needed | Approximate Cost |
|---|---|---|---|---|
| 5,000 kWh | 4 kW | 10 panels | 180 sq ft | $10,000 - $14,000 |
| 8,000 kWh | 6 kW | 15 panels | 270 sq ft | $14,000 - $20,000 |
| 12,000 kWh | 9 kW | 23 panels | 410 sq ft | $20,000 - $28,000 |
| 16,000 kWh | 12 kW | 30 panels | 540 sq ft | $26,000 - $36,000 |
| 20,000 kWh | 15 kW | 38 panels | 680 sq ft | $32,000 - $44,000 |
Sizes assume 1,400-1,800 kWh production per kW installed (varies by location — use PVWatts calculator for your specific address).
Utility Rate Analysis:
| Electricity Rate | Solar ROI | Notes |
|---|---|---|
| Below $0.08/kWh | Poor | Solar rarely makes sense unless rates are rising rapidly |
| $0.08 - $0.12/kWh | Marginal | With ITC, breakeven in 10-15 years |
| $0.12 - $0.16/kWh | Good | Breakeven in 7-10 years. Solid investment |
| $0.16 - $0.22/kWh | Strong | Breakeven in 5-8 years. Excellent investment |
| Above $0.22/kWh | Exceptional | Breakeven in 4-6 years. Install as soon as possible |
Buy vs. Lease vs. PPA Comparison:
| Factor | Buy (Cash) | Buy (Loan) | Lease | PPA |
|---|---|---|---|---|
| Ownership | You own | You own | Leasing company owns | Provider owns |
| Upfront cost | $15,000-$30,000 | $0 down | $0 down | $0 down |
| Monthly payment | $0 | Loan payment | Lease payment | Per-kWh rate |
| ITC benefit | You get 30% | You get 30% | Company keeps it | Company keeps it |
| Total 25-year savings | Highest | High | Lowest | Low |
| Maintenance responsibility | You | You | Leasing company | Provider |
| Home sale impact | Adds value | Adds value (transfer loan) | Complicates sale | Complicates sale |
| Best for | Homeowners with cash/equity | Most homeowners | Renters, short-term owners | Renters, short-term owners |
Strong recommendation: Buy the system (cash or loan) whenever possible. Leases and PPAs sacrifice 40-60% of the total financial benefit. The 30% ITC alone often covers the down payment on a solar loan.
Battery Storage Decision Framework:
| Factor | Battery Makes Sense | Battery Does Not Make Sense |
|---|---|---|
| Net metering | Reduced or no net metering | Full retail net metering |
| Outage frequency | Frequent outages (>4/year) | Rare outages (<1/year) |
| TOU rates | Large peak/off-peak spread (>$0.10 difference) | Flat rates |
| Critical loads | Medical equipment, sump pump, security | No critical loads |
| Budget | Can afford $10,000-$15,000 additional | Budget-constrained |
| Grid reliability | Unreliable (rural, storm-prone) | Very reliable |
Common Failure Modes
- Inverter failure at year 8-12 (string inverters): This is the most common solar system failure. Most string inverters have a 10-12 year warranty. Budget for one replacement. Micro-inverters avoid this issue with 25-year warranties but cost 10-15% more upfront
- Hot spot damage: A shaded or damaged cell in a panel can overheat and damage the panel. Bypass diodes mitigate this but do not eliminate it. Panel-level monitoring (micro-inverters or optimizers) detects hot spots early
- Roof penetration leak: Improperly sealed mounting bolts leak over time. Quality installations use flashing and sealant rated for 25+ years. Inspect after 5 years and after any major storms
- Critter guard failure: Squirrels and birds nest under panels, damaging wiring. Critter guard (wire mesh around the panel perimeter) is a recommended add-on ($500-$1,000)
- Production degradation: Panels degrade at ~0.5%/year. This is normal and accounted for in financial projections. Degradation above 1%/year indicates a quality or installation issue
Diagnostic Procedures
- Review monitoring data: Compare monthly production to expected output (use PVWatts as a benchmark). Production within 90% of expected is normal; below 80% warrants investigation
- Check each panel (if micro-inverters or optimizers are installed): Individual panel production should be within 10% of its neighbors. An outlier indicates a panel issue, shading, or inverter fault
- Inspect panels visually: Look for cracks, discoloration, delamination, snail trails (micro-cracks visible as lines on the cell surface)
- Check inverter: Error codes, efficiency rating, and power output vs. rated capacity
- Inspect wiring and conduit: Look for damage, loose connections, rodent gnawing
- Check roof penetrations: Any signs of water intrusion around mounting points
- Review utility bills: Verify net-metering credits are being applied correctly
Code & Compliance
- Solar installation requires an electrical permit and inspection in all jurisdictions
- Structural review may be required to verify the roof can support the added weight (3-5 lbs/sq ft)
- Utility interconnection agreement must be signed before the system is energized
- Rapid shutdown is required by NEC 2017+ (modules must de-energize within 30 seconds of grid disconnection)
- Fire setback requirements vary by jurisdiction (typically 3-foot pathways on the roof for firefighter access)
- HOA restrictions: the Solar Access Act in many states prevents HOAs from prohibiting solar but may allow "reasonable" aesthetic restrictions
- Battery storage requires fire department notification in some jurisdictions and may have specific installation requirements (distance from sleeping areas, ventilation)
Cost Guide
| Component | Cost Range | Notes |
|---|---|---|
| Solar panels (per watt, installed) | $2.50 - $3.50/W | Includes panels, inverter, mounting, labor |
| 6 kW system (before incentives) | $15,000 - $21,000 | Typical 3-bed home |
| 10 kW system (before incentives) | $25,000 - $35,000 | Larger home or EV + HVAC |
| 30% ITC (on 6 kW) | -$4,500 to -$6,300 | Federal tax credit |
| Net cost after ITC (6 kW) | $10,500 - $14,700 | Before state/utility incentives |
| Battery storage (per unit) | $10,000 - $15,000 | Tesla Powerwall, Enphase IQ |
| Battery ITC (30%) | -$3,000 to -$4,500 | Standalone batteries now qualify |
| String inverter replacement | $1,500 - $3,000 | At year 10-15 |
| Annual maintenance | $100 - $300 | Cleaning + inspection |
ROI Calculator Inputs:
System cost after ITC: $_______
Annual electricity offset: $_______ (current rate x kWh produced)
Annual rate increase (est): 3-5% per year
Loan interest (if financed): $_______/year
Maintenance reserve: $200/year
Inverter replacement (yr 12): $2,000 (amortize over 25 years = $80/year)
Year 1 net savings: (electricity offset) - (loan payment) - (maintenance)
Payback year: when cumulative savings = system cost
25-year total savings: typically $30,000-$60,000 for a purchased system
Energy Impact
A properly sized solar system offsets 70-100% of a home's electricity consumption. For a home using 10,000 kWh/year at $0.15/kWh:
- Annual electricity cost without solar: $1,500
- Annual cost with solar (grid-tied, net-metered): $0-$300
- Annual savings: $1,200-$1,500
- 25-year savings (with 3% annual rate increases): $45,000-$55,000
- System cost after ITC: $14,000-$18,000
- Net 25-year profit: $27,000-$37,000
Solar plus battery storage can achieve 90-100% energy independence, virtually eliminating the electricity bill and providing backup power during outages.
Shipshape Integration
How SAM Informs the Solar Decision:
SAM provides the most accurate solar assessment available by using actual home data rather than estimates:
- Consumption baseline: SAM knows the home's actual electricity consumption patterns — hourly, daily, and seasonally. This is far more accurate than estimating from utility bills, enabling precise system sizing
- Post-solar monitoring: After installation, SAM tracks production vs. consumption in real time, verifying the system performs as projected. "Your solar system produced 820 kWh in March — 95% of projected output. Your self-consumption ratio is 62%."
- Degradation tracking: SAM compares year-over-year production normalized for weather. "Your panels are degrading at 0.4% per year — well within normal range" or "Production has dropped 8% year-over-year despite similar weather — recommend an inspection"
- Self-consumption optimization: SAM schedules high-draw devices (EV charger, heat pump water heater, dishwasher) to coincide with peak solar production, maximizing self-consumption and minimizing grid export (especially valuable in states with low net-metering rates)
- Battery optimization: For homes with battery storage, SAM manages charge/discharge cycles to maximize value — charging from solar, discharging during peak TOU hours, and reserving capacity for outage protection
- ROI tracking: SAM maintains a running total of energy savings, showing the homeowner their actual return: "Your solar system has saved you $4,280 since installation. Projected payback: month 82 of 96."
Dealer Opportunity: Solar assessment and installation is a high-value service. Shipshape data gives dealers the critical advantage of knowing exactly how much electricity each customer uses, what their peak demand looks like, and whether the home's envelope should be improved first (per the upgrade prioritization framework). A Shipshape-informed solar proposal is more credible than a generic door-to-door pitch. The dealer dashboard shows which customers have high electricity costs (prime solar candidates) and which have already improved their envelope (ready for right-sized solar). Post-installation, the ongoing monitoring creates a service relationship: annual inspections, inverter replacement planning, and battery storage upsell when net-metering policies change.