Inverter Clipping and DC-to-AC Ratios in Plain Terms

If you’ve noticed that your solar system never quite hits its full advertised kilowatt output — you’re not alone. Many solar owners are surprised to see their system rated at 10 kW, yet the monitoring app never shows it producing more than 7 or 8 kW at a time. Some worry something’s wrong — or worse, that they were sold a system that underperforms.

But there’s a technical and very intentional reason for this, and it actually benefits most homeowners — especially in the Pacific Northwest.

DC Ratings vs. AC Output

The kilowatt rating of your solar system typically refers to the total DC power capacity of the solar panels — the maximum amount of power they’re capable of producing under ideal conditions. But your home — and the grid — runs on AC (alternating current), so all that DC power has to run through an inverter to be usable.

Here’s where the important difference comes in: the inverter has its own maximum power limit, usually measured in AC kilowatts, and in many systems, the inverter is intentionally smaller than the total panel capacity.

What’s a DC-to-AC Ratio?

The DC-to-AC ratio compares the total wattage of your solar panels to the size of your inverter. For example:

• 10 kW of solar panels with an 8 kW inverter = 1.25 DC-to-AC ratio 

Many well-designed systems have ratios between 1.1 and 1.3 — and sometimes even higher. This approach is deliberate and smart, especially in climates like ours.

What Is Inverter Clipping?

When the sun is strongest — typically midday on clear days — your panels might produce more power than the inverter can handle. The inverter responds by “clipping” the output to stay within its maximum AC limit. That means you might see your system flatline at 7.6 or 8 kW, even if the panels could technically produce more in that moment.

Think of it like a highway on-ramp. During light traffic, cars (solar energy) flow freely onto the freeway (your inverter). But at rush hour, if too many cars show up at once, the metering lights hold some back. The system still runs efficiently — just not at full blast every moment.

Why Not Just Use a Bigger Inverter?

You could — but it’s not usually worth it.

In the Pacific Northwest, we deal with a wide range of weather — clouds, rain, haze, and short winter days. These conditions mean your panels rarely operate at full power. In fact, much of the year they’re working at partial output. A slightly smaller inverter lets the system perform more efficiently across a wide range of conditions, rather than being oversized for the fewer, perfect months each year.

Plus, the cost of adding more panels is relatively marginal. The expense of adding a second inverter or upgrading to a significantly larger one is much higher — not just in equipment, but in installation, labor, and permitting. You’ll often get better value by spending that budget on more panel coverage, rather than extra inverter capacity you rarely need.

The Big Picture

• The graphic above illustrates the advantages of a high DC-to-AC ratio — the benefits are found in sections A & C.
• Your system’s nameplate (e.g. 10 kW) refers to the maximum potential output of your panels under perfect conditions (B). 
• The inverter — which limits how much power can be converted and used at any one time — may be intentionally undersized. 
• Clipping happens only during peak sun conditions and is built into the design to give you the best performance year-round. 
• A slightly undersized inverter helps you capture more energy over the year, especially in a region with variable sunlight like the PNW. 
• Investing in more panels is usually more cost-effective than overbuilding your inverter capacity. 

Conclusion: Getting a Smarter System

A solar system isn’t just designed for one perfect sunny day. It’s built for your whole year. By pairing your panels with the right inverter — even if that means a bit of clipping — you’re getting a system that works harder, longer, and with maximum cost-efficiency.