The short version
- Residential solar is quoted per watt of capacity; most US homeowners see $2.50–$3.50 per watt before incentives.
- A typical 7 kW system therefore lands around $18,000–$25,000 before any credits or rebates.
- Labour, permitting and an electrical panel upgrade can matter more to your total than the panel brand.
- Adding a battery commonly adds $10,000–$18,000 and is a separate decision from the panels.
Why everything is priced per watt
Installers quote in dollars per watt of installed capacity because it is the only figure that lets you compare a 5 kW system on a simple roof with a 12 kW system on a complicated one. Multiply the rate by the system size and you have the pre-incentive price.
As a planning range, most US residential quotes fall between $2.50 and $3.50 per watt. Below that band, ask what has been left out. Above it, ask what the extra is buying — sometimes it is a genuinely harder install, sometimes it is sales commission.
| System size | Roughly suits a bill of | Indicative cost before incentives |
|---|---|---|
| 4 kW | Under $100/mo | $10,000 – $14,000 |
| 6 kW | $100 – $150/mo | $15,000 – $21,000 |
| 8 kW | $151 – $250/mo | $20,000 – $28,000 |
| 11 kW | $250 – $400/mo | $27,500 – $38,500 |
| 14 kW | $400+/mo | $35,000 – $49,000 |
What is actually in the price
Hardware is less than half of a typical residential quote. The rest is the work of getting it legally installed and connected.
- Panels. The most visible cost and often the smallest lever. The gap between a mid-tier and premium panel is usually a few cents per watt.
- Inverter. String inverter, microinverters or optimisers. Microinverters cost more and handle partial shade better, which matters if any part of your roof is obstructed.
- Racking and mounting. Tile and slate roofs cost more to work on than asphalt shingle. Steep pitches and multiple roof planes add labour.
- Electrical work. The quiet budget-breaker. Older homes often need a main panel upgrade, typically $2,000–$4,000, before an array can be connected.
- Permits, inspection and interconnection. Varies enormously by jurisdiction. Some cities process in days; others take months and charge accordingly.
- Sales and overhead. Real, and larger than most homeowners expect. This is where quotes for identical hardware diverge most.
The four things that move your number most
- How much power you actually useSystem size follows consumption, and consumption is the single biggest driver of cost. Pull twelve months of bills before you talk to anyone.
- Your roofAge, material, pitch and how many separate faces the array has to be split across. A single unshaded south-facing plane is the cheapest case.
- Your electrical panelIf it cannot accommodate a solar backfeed breaker, an upgrade is not optional.
- Where you liveLabour rates, permitting fees and utility interconnection requirements vary by thousands of dollars between neighbouring states — and what your utility pays for exported power changes the payback far more than the price does. Solar by state has the local picture.
- What it costs after year oneVery little, in most climates — but "very little" is not nothing, and one inverter replacement is a realistic line in a 25-year budget. What solar maintenance actually costs.
Telling a fair quote from a padded one
Get three quotes, then compare them on the same basis:
- Normalise to dollars per watt. A "cheaper" quote for a smaller system is not cheaper.
- Compare estimated annual production, not just capacity. kWh per year is what you actually buy.
- Check what is excluded. Panel upgrade, tree trimming, roof repair and permit fees are the usual omissions.
- Read the warranty terms. Product, performance and workmanship warranties are three different things with three different lengths.
- Be wary of urgency. "This price expires tonight" is a sales technique, not a market condition.
Cost is not the same as what you pay
Incentives, and how you finance the system, change the number that reaches your bank account by a lot. A cash purchase has the lowest lifetime cost; a loan spreads it but adds interest; a lease or power-purchase agreement usually means no upfront cost and no ownership — which also means the tax credit is not yours.
We walk through that trade-off in solar lease vs. loan vs. buying outright, and how incentives apply in the federal solar tax credit explained.