Quick answer
A home solar system is three pieces working together: solar panels that turn sunlight into DC electricity, an inverter that converts that DC into the AC power your outlets use, and (optionally) batteries that store energy for night or outages — plus the wiring and breakers that hold it together safely. In one sentence you can repeat to a neighbor: panels make the power, the inverter makes it usable, and the battery decides whether you still have power when the sun isn’t shining. Everything else — sizing, costs, wiring, payback — is detail on top of that picture; the full system planning guide works through the design order. One 2026 fact belongs in the picture from the start: the 30% federal tax credit expired December 31, 2025, so a system installed this year gets no federal credit and pays back over roughly 10–13 years in high-cost states.
Key takeaways
- A complete system is panels (DC) + inverter (DC→AC) + optional battery + wiring and protection. Nothing else is mandatory.
- Four questions decide the whole design: what you want to power, how much sun you get, whether you stay on the grid, and what you’ll spend.
- Grid-tied is the cheapest per watt ($2.50–$3.50/W installed) but shuts down in an outage; hybrid adds battery backup for ~$1,000–$1,400/kWh installed; off-grid is the most expensive per kWh but fully self-sufficient.
- Sizing starts with daily watt-hours, not peak watts: a ~1,820 Wh/day load needs roughly 570W of panels at 4 peak sun hours and a ~4.3kWh battery for two days of autonomy.
- The 30% federal ITC expired December 31, 2025 (P.L. 119-21). Budget 2026 installs with no federal credit and a 10–14 year payback nationally — 10–13 years in high-cost, high-rate states.
The four questions that determine any system
Every solar project, from a 100W shed setup to a whole-house install, is settled by four questions. Answer them in order and the design basically writes itself.
1. What do you want to power?
Start with the load list, not the panels. The unit that matters is watt-hours per day (Wh/day) — each appliance’s watts times the hours you actually use it — because that’s what the panels and battery have to supply.
Worked example for a modest home setup:
- Refrigerator: 150W running × 40% duty cycle × 24h = 1,440 Wh/day (the compressor cycles rather than running nonstop)
- Ten LED bulbs at ~5W each, 4h/day: 10 × 5W × 4h = 200 Wh/day
- Laptop charger, 60W for 3h: 60 × 3 = 180 Wh/day
- Total: ~1,820 Wh/day
For the full method (including surge loads and seasonal peaks), see our load calculation guide.
2. How much sun do you get?
Panel ratings assume full, noon-equivalent sun, so location is a sizing input, not an afterthought. The standard measure is peak sun hours per day — per NREL solar resource data, most of the continental US falls in the 3–6 hour range, with winter typically half of summer.
Panel watts ≈ daily Wh ÷ (sun hours × 0.8), where 0.8 covers angle, temperature, and charge-controller losses:
- 1,820 Wh/day at 4 sun hours: 1,820 ÷ (4 × 0.8) = ~570W of panels
- Same load at 3 sun hours (winter, northern state): 1,820 ÷ (2.4) = ~760W
- Same load at 5 sun hours (sunny southwest): 1,820 ÷ (4.0) = ~455W
That spread is why “how many panels do I need” has no single answer — the sun hours figure is the variable. Use our panel output calculator with your zip code.
3. Grid or no grid?
- Grid-tied: your system stays connected to the utility. Excess daytime power is exported, usually for credits under net metering, and you buy power at night. This is the cheapest design and the most common home setup.
- Off-grid: no utility connection at all. Your battery bank is the only supply after dark and through cloudy stretches, so the system must be sized for your worst season, not your average one.
- Hybrid: grid-tied plus a battery and a backup-capable inverter. It exports like a grid-tied system but can also run backed-up circuits during an outage.
Net metering rules vary sharply by state — see our net metering by state (2026) roundup.
4. What’s the budget?
Installed residential pricing runs $2.50–$3.50 per watt, so a typical 6kW system quotes $15,000–$21,000. Buying the same components yourself and doing the work lands 40–60% lower — roughly $5,100–$9,600 in parts for that 6kW. Batteries are billed at $1,000–$1,400 per kWh installed, while DIY LiFePO4 cells run $150–$300 per kWh.
And the budget line changed in 2026: the 30% federal investment tax credit expired December 31, 2025 under P.L. 119-21. Installations in 2025 can still claim it; 2026 installations get no federal credit. Without it, payback runs roughly 10–14 years nationally, and 10–13 years in high-cost, high-rate states. Our solar system cost breakdown works the full three-tier math.
| System tier | Installed total | DIY parts total | What it powers |
|---|---|---|---|
| ~2kW off-grid cabin (with ~5kWh battery) | Rarely quoted — installers seldom take small off-grid jobs | $4,000–$8,500 | Lights, fridge, water pump, electronics |
| ~6kW grid-tied home (no battery) | $15,000–$21,000 | $5,100–$9,600 | Offsets most of a typical home's annual kWh |
| ~10kW home + 10kWh battery | $35,000–$48,000 | $12,800–$25,500 | Whole-home offset plus 12–24h of backup |
Grid-tied vs hybrid vs off-grid
The three architectures answer the same question — “does it work when the grid fails?” — very differently. That single behavior drives price and design more than any other choice.
| Type | What it does | Typical cost scale | Works in an outage? |
|---|---|---|---|
| Grid-tied | Panels + inverter, connected to the utility. Excess power is exported for credits (net metering); you draw from the grid at night. | Lowest: $2.50–$3.50/W installed, no battery | No. The inverter must detect the outage and shut down within seconds (anti-islanding protection per UL 1741 / IEEE 1547) to protect utility workers. |
| Hybrid | Grid-tied plus battery and a backup-capable inverter. Runs on solar and grid during the day, banks surplus, and can island selected circuits in an outage. | Middle: grid-tied cost + $1,000–$1,400/kWh installed for the battery | Yes, for backed-up circuits — typically hours to a day, depending on battery size and what you run. |
| Off-grid | No utility at all. Panels, battery, and inverter must cover every load, every day, worst season included. | Highest per kWh delivered — the battery bank is large and must handle winter autonomy | Yes — that's the point. But only for as long as the battery bank is sized to last. |
The honest summary: if your utility offers fair net metering and you don’t need outage power, grid-tied is the best value. The moment “I want power when the grid goes down” becomes a requirement, you’re buying a battery — and that roughly doubles the total cost on an installed quote.
The 60-second version of sizing
The full method (with an interactive load planner) lives in our how to size a solar system guide. The compressed version is four steps:
- Daily load: add up watts × hours of use for everything that runs. (Our example: ~1,820 Wh/day.)
- Panels: daily Wh ÷ (sun hours × 0.8). (1,820 ÷ 3.2 ≈ 570W at 4 sun hours.)
- Battery: days of autonomy × daily Wh ÷ usable depth of discharge. (2 × 1,820 ÷ 0.85 ≈ 4,280 Wh — about 4.3kWh usable with LiFePO4’s ~80–90% DoD.)
- Inverter: cover the worst simultaneous running watts plus ~25% headroom, then verify surge. (Our fridge alone: 150W continuous, ~800W surge.)
| Step | Formula | Our example result |
|---|---|---|
| Daily load | Σ (watts × hours) | ~1,820 Wh/day |
| Panel array | daily Wh ÷ (sun hrs × 0.8) | ~570W at 4 sun hours |
| Battery (2 days autonomy) | 2 × daily Wh ÷ 0.85 | ~4.3kWh usable (LiFePO4) |
| Inverter | peak running × 1.25, surge verified | 150W-continuous / 800W-surge class for the fridge |
Two realities to accept before you start: a single 100W panel cannot run a fridge (that example needs ~570W), and your battery — not the weather — is what carries you through cloudy days. Solar is a recharge source; storage is the guarantee.
What this site covers
- Sizing and load math: calculators for panel output, battery capacity, inverter sizing, and load planning, with the arithmetic shown, not hidden.
- Component decisions: panels (mono vs poly), inverters (micro vs string, MPPT vs PWM controllers), batteries (LiFePO4 vs lead-acid), and system voltage — each with comparison tables and honest trade-offs.
- Costs, incentives, and wiring: the cost guides hub with regional pricing, the installed vs DIY breakdown, the 2026 incentive reality (no federal ITC), and a full wiring and protection cluster for the safety-critical part.
What this site is not: a place that claims “we tested” gear or quotes brand-marketing numbers. Every figure here is a conservative, verifiable range — check the sibling pages, they show their work.
Common beginner mistakes
Three mistakes show up in nearly every first project. All are avoidable:
- Buying gear before measuring loads. A random “100W panel + 100Ah battery” bundle bought before you know your daily watt-hours is how people end up with a system that charges a phone but won’t start the fridge. Do the load list first — it takes an evening and an extension cord with a $20 wattmeter.
- Sizing for summer sunshine. If your numbers work in July but the system is used in December, you’ve undersized the array and the battery both. Off-grid systems should be sized for the worst season, not the average or the best.
- Underestimating soft costs and the battery bill. On an installed quote, hardware is only 40–50% of the total — labor and soft costs (permits, interconnection, sales margin) make up the rest. And on battery systems, storage is billed at $1,000–$1,400/kWh installed versus $150–$300/kWh for DIY cells. The gap between a $15,000 and a $35,000 quote is usually the battery line plus labor, not the panels.
FAQ
How do solar panels produce electricity?
What is the difference between DC and AC power?
Do solar panels work on cloudy days?
How long do solar panels last?
Does solar work during a power outage?
Is solar worth it in 2026 without the federal tax credit?
Next logical reads
How do solar panels work — the photovoltaic effect and panel technology Solar use-case guides Solar components explained Solar yard lights buying guide Solar phone chargers Portable solar panels Solar components explained — panels, inverters, charge controllers, batteries How to size a solar system — the full step-by-step with the interactive planner Solar wiring decisions — wire size, fuses vs breakers, series vs parallel Solar system cost breakdown — installed vs DIY tiers, line by line Cost guides hub — regional panel and battery pricing guides
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