Panels are quoted per watt and everyone compares them. The inverter is quoted as a line item and almost nobody does — which is odd, because it is the component with the shortest life and the widest price spread on the whole system.
Price per watt
| Type | $/W of array | 6 kW system | 10 kW system |
|---|---|---|---|
| String inverter | $0.10–0.20 | $600–1,200 | $1,000–2,000 |
| String + DC optimisers | $0.20–0.32 | $1,200–1,900 | $2,000–3,200 |
| Microinverters | $0.25–0.40 | $1,500–2,400 | $2,500–4,000 |
| Hybrid (battery-ready) | $0.30–0.55 | $1,800–3,300 | $3,000–5,500 |
US installed-equipment ranges at the time of writing, before labour. The spread inside each row is mostly brand and warranty length, not capability.
On a typical residential quote the inverter is 8–15% of the total. Panels are 25–35%, and labour, racking, permitting and margin are the rest.
What each one is actually buying
String inverter. One box, all panels wired in series strings. Cheapest per watt, highest efficiency, one point of failure. Shading on one panel drags down the whole string it sits in.
String plus optimisers. A small device per panel that handles the mismatch, feeding one central inverter. Recovers most of the shading loss for roughly half the microinverter premium.
Microinverters. One inverter per panel, on the roof. Per-panel monitoring, no single point of failure, and the conversion happens at the panel so there is no high-voltage DC on the roof. The cost is that you now have twenty electronic devices under the panels instead of one in the garage.
Hybrid. A string inverter with a battery port and, usually, a backup output. Paying for this without a battery is a bet that you will add one — see how many batteries for off-grid for what that battery ends up costing.
The replacement nobody quotes
This is the number that changes the comparison.
| Component | Expected life | Warranty |
|---|---|---|
| Panels | 25–30 yr | 25 yr performance |
| Racking | 25+ yr | 10–25 yr |
| String inverter | 10–15 yr | 5–12 yr, extendable |
| Microinverters | 15–25 yr | 20–25 yr standard |
A 25-year system on a string inverter is very likely a two-inverter system. Add a replacement at year 12 — the unit plus a few hours of labour — and the cheap option closes a large part of the gap on its own.
Worked example, 8 kW system over 25 years:
- String: $1,400 now + ~$1,800 replacement at year 12 = $3,200
- Microinverters: $2,800 now, 25-year warranty = $2,800
The order reverses. It reverses further if the roof is shaded, and back again if the array is a single unshaded plane where the string inverter never gives anything up.
How to read the line on a quote
Three questions:
- What is the inverter warranty, in years, and is an extension priced? A 5-year warranty on a 25-year system is a decision being made for you.
- Is it sized to the array or to the panels? A 7.6 kW inverter on an 8 kW array is normal and correct — arrays rarely hit nameplate, and modest DC/AC oversizing is standard practice, not a shortfall.
- If it is hybrid, what does the battery port actually accept? Many hybrids only work with one manufacturer's battery, which quietly picks your battery brand years in advance.
Where the money is, in order
If the budget is fixed, spend it in this order:
- Array size — every extra panel produces for 25 years
- Inverter warranty — the cheapest way to avoid the year-12 bill
- Optimisers, but only if there is real shading — on a clean south roof they buy nothing
- Battery-ready hybrid, only if the battery is actually planned
Microinverters versus string is not a quality question. It is a roof question: shading, multiple planes and awkward orientations make the case, and a single clean plane does not.