Summer is when most US solar installs happen — long sun hours, dry roofs, and peak air-conditioning bills make the economics obvious. But 2026 is a different landscape than the last few years: the federal incentive picture changed, and the numbers only work if you size the system correctly and understand how your state credits the power you export.
This guide covers the four things people actually want to know: how to size a system, what each size can run, how much it saves, and which US laws and incentives apply in 2026. We finish with the part most homeowners and installers get wrong — the wiring connections that decide whether a 25-year system actually lasts 25 years.
Note: This article is general educational information, not tax, legal, or financial advice. Solar incentives and net-metering rules change frequently and vary by state and utility. Confirm current federal rules at IRS.gov and state/local programs at the DSIRE database, and consult a qualified tax professional before making decisions.
How to Size a Solar System
System sizing comes down to one formula. Start with your average daily electricity use (find the kWh on your power bill, or divide your monthly kWh by 30):
System kW = Daily kWh ÷ Peak Sun Hours ÷ 0.8
The 0.8 accounts for real-world losses: inverter efficiency, wiring, heat, soiling, and panel tolerance.
Peak sun hours are the equivalent hours of full-strength sunlight your location gets per day — not daylight hours. Most of the US averages 4 to 5.5; the desert Southwest is higher, the Pacific Northwest lower. A worked example for a typical home:
| Step | Calculation | Result |
|---|---|---|
| Monthly usage | 900 kWh ÷ 30 days | 30 kWh/day |
| Divide by sun hours | 30 ÷ 4.5 | 6.67 |
| Apply loss factor | 6.67 ÷ 0.8 | 8.3 kW system |
| Panel count (400W panels) | 8,300W ÷ 400W | ≈ 21 panels |
So a household using 900 kWh a month in an average-sun region needs roughly an 8 kW system of about 21 panels. If you plan to add an EV or electrify heating, size up now — it's cheaper than expanding later.
What Each System Size Can Run
To match a system to your needs, start from the load. Here is the typical power draw of common devices — multiply watts by hours of use to get daily watt-hours (Wh):
| Device | Typical Draw | Notes |
|---|---|---|
| LED light | 9 W | Negligible — run dozens easily |
| Wi-Fi router / phone | 10 W | Always-on base load |
| Laptop | 50 W | Low draw, long runtime |
| LED TV | 80 W | ~0.4 kWh over an evening |
| Refrigerator | 150 W running | ~1–2 kWh/day (cycles on/off) |
| Microwave | 1,000 W | Short bursts |
| Window AC unit | 900–1,440 W | The big summer load |
| Central AC | 3,000–5,000 W | Needs a large system + good sun |
| Well / water pump | 750–1,500 W | High startup surge |
| EV charger (Level 2) | 7,200 W | Effectively doubles many homes |
Mapped to system tiers, that translates to:
100–200W — Portable / RV / Marine
Lights, phone charging, a router, a small 12V fan, and a few hours of laptop use with a battery. The classic off-grid starter for vans, boats, and campsites. This is the world of 12V DC wiring where sealed connections matter most.
400–600W — Off-Grid Cabin Essentials
Adds a 12V fridge, a water pump, and longer device runtimes. Enough for a weekend cabin or a well-equipped overland rig with a couple of batteries.
2–4 kW — Small Home (No Heavy AC)
Covers a small home's lights, fridge, electronics, and intermittent appliances — but not central air conditioning running all day.
6–10 kW — Typical Whole US Home
The range most grid-tied residential installs land in. Offsets most or all of an average home's usage including window-unit AC, with net metering smoothing out the daily swings.
10 kW+ — Large Home, Central AC, EV
Required once you add central air conditioning, electric heating, or EV charging. Size deliberately — these loads can double a household's demand.
How Much Solar Saves on Your Bill
Annual production is system size × peak sun hours × 365 × 0.8. Multiply by your electricity rate for the gross savings. Using the 8 kW system from earlier, at the US average residential rate of about 17¢/kWh:
| Figure | Calculation | Result |
|---|---|---|
| Annual production | 8 kW × 4.5 × 365 × 0.8 | ≈ 10,500 kWh/yr |
| Annual savings | 10,500 × $0.17 | ≈ $1,785/yr |
| 10-year savings | $1,785 × 10 | ≈ $17,850 |
| 25-year (system life) | illustrative, before rate inflation | ≈ $44,600 |
Treat these as illustrative. Two factors move them hard in both directions: your actual electricity rate (it ranges from ~11¢ to over 30¢/kWh by state — high-rate states pay back far faster) and net metering, which decides what your exported daytime power is worth. Panel output also degrades ~0.5% a year, while utility rates historically rise — the two roughly offset over the system life.
US Solar Laws & Incentives in 2026
This is the area that changed most — and where outdated advice is everywhere. Here is the accurate 2026 picture.
Federal: the 30% residential credit has ended
The federal Residential Clean Energy Credit (Section 25D) — the 30% credit homeowners relied on — was terminated by the One Big Beautiful Bill Act (signed July 4, 2025) for systems placed in service after December 31, 2025. There is no phase-down: a homeowner buying with cash or a loan in 2026 gets no federal tax credit. Verify against the IRS's OBBB modification FAQ.
The remaining federal path: third-party-owned systems. With a lease or power purchase agreement (PPA), the financing company owns the system and claims the 30% commercial credit (Section 48E, currently available through 2027), passing the benefit to you through lower payments. You don't own the system, but you still capture an effective federal subsidy.
State: net metering is now the main lever
With the federal credit gone for owners, state net-metering policy is the biggest factor in whether solar pays off. About 38 states plus DC have net metering or net billing, but the difference between them is large:
Full Retail Net Metering
Exports credited at the full retail rate — the best case. Strongest in New Jersey, Massachusetts, Maine, New York, Maryland, Connecticut, and Vermont.
Net Billing (avoided cost)
Exports credited at a lower wholesale/avoided-cost rate. About a third of states have shifted this way — California's NEM 3.0 cut export credits by roughly 75% for new systems.
State Tax Credits & Rebates
Several states still offer their own income-tax credits, upfront rebates, or performance payments (SRECs) — these can be significant. Look yours up on DSIRE.
Property & Sales Tax Exemptions
Many states exempt solar from added property tax (the value boost isn't taxed) and/or waive sales tax on equipment. Quiet but real savings.
Because these vary by state and by utility, the single most useful step you can take is to look up your exact location in the DSIRE database (the Database of State Incentives for Renewables & Efficiency) and confirm your utility's current net-metering or net-billing tariff before you sign anything.
The Part Installs Get Wrong: the Connections
A solar system is sold on a 25-year horizon, but it only lasts that long if the connections do. PV wiring lives outdoors under constant UV, daily thermal cycling, and moisture — the harshest environment short of marine. Every unsealed joint is a future failure point, and a single corroded connection can drag down a whole string's output.
The fix is UV-stabilised 3:1 dual wall adhesive-lined heat shrink at the vulnerable points: MC4 connector tails, string-to-combiner transitions, grounding lugs, and especially the battery-bank lugs on off-grid and hybrid systems. The adhesive bonds to the cable jacket and seals the conductor against the 25 years of weather the panels are warrantied for.
For the full method — sizing, ratios, and the seal procedure for each connection type — see our dedicated heat shrink for solar & PV wiring guide and the battery terminal guide for off-grid banks.
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Browse All Sizes
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Frequently Asked Questions
How many solar panels do I need to run a house?
Divide your daily kWh use by your local peak sun hours (typically 4–5.5 in the US), then by about 0.8 for system losses, to get system size in kW. Divide by panel wattage (~400W) for the count. A typical home using 30 kWh/day in a 4.5 sun-hour region needs roughly 8.3 kW — about 21 panels.
Is there still a federal solar tax credit in 2026?
Not for cash or loan purchases. The 30% Residential Clean Energy Credit (Section 25D) expired December 31, 2025 under the One Big Beautiful Bill Act, with no phase-down. The only remaining federal path is a lease or PPA, where the financing company claims the 30% commercial credit (48E, through 2027) and passes it on. Confirm with a tax professional and IRS.gov.
How much can solar save on my electricity bill?
It depends on system size, local sun, your rate, and net metering. As an illustration, an 8 kW system in a 4.5 sun-hour region produces ~10,500 kWh/yr; at the ~17¢/kWh US average that is about $1,785/yr offset. High-rate states save much more; low export credits under net billing reduce it.
What can a small solar system actually run?
A 100–200W system with a battery runs lights, phone charging, a router, and a small fan — great for RV, marine, or camping. 400–600W adds a laptop and a 12V fridge or pump. 2–4 kW covers a small home minus heavy AC. A whole home typically needs 6–10 kW, and central AC or EV charging pushes past 10 kW.
Does net metering still exist in 2026?
Yes, but it varies by state. ~38 states plus DC have net metering or net billing, but about a third have shifted to lower-value net billing. Strong full-retail states include NJ, MA, ME, NY, MD, CT, and VT; California cut credits sharply under NEM 3.0. Check your state and utility on DSIRE.
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