Quick answer
A solar inverter is the device that converts the direct current (DC) made by solar panels into the alternating current (AC) used by a home’s outlets and the utility grid, while matching the grid’s voltage and frequency.
It also manages the panels for best output, shuts down or rides through grid problems as standards require, and, in hybrid designs, charges and discharges a battery.
Quick facts
The key facts about Solar Inverter, with sources:
- Job
- Convert panel DC to grid-matched AC 2
- Main types
- Central, string, micro; plus power optimizers and hybrid/battery inverters 1
- String trade-off
- Shade or a fault on one panel lowers output for the whole string 1
- Micro trade-off
- Each panel works on its own; can cost more 1
- Grid standard
- IEEE 1547-2018; certified through UL 1741 (Supplement SB) 3
- In an outage
- Grid-tied systems shut down unless designed with storage to run alone 1
Key takeaways
- Panels make DC; your home runs on AC. The inverter is the translator between them.
- String inverters are one box for many panels; microinverters sit under each panel.
- Standard grid-tied inverters shut off in an outage to protect line workers.
- Modern inverters must meet IEEE 1547-2018 grid-support rules, tested through UL 1741 SB.
- An inverter is part of the electrical service work, so it is permitted and inspected.
What a solar inverter does
Solar panels make direct current, power that flows one way like a battery’s. Your outlets, appliances and the utility grid use alternating current, which reverses direction many times a second. EIA explains that inverters are used on PV panels or arrays to convert DC electricity to AC 2.
An inverter does more than flip DC to AC. It finds the best operating point for the panels as light changes through the day. It times its output to match the grid’s voltage and its 60-hertz frequency. It also watches the grid and decides when to keep running and when to disconnect.
The DOE notes that modern inverters can also supply and absorb reactive power to help keep voltage steady on the grid 1. That grid-support role is why inverter rules have grown stricter in recent years.
How power flows through the inverter
- Sunlight → panels make DC
- DC → inverter tracks the panels’ best operating point
- Inverter → AC matched to grid voltage and 60 Hz
- AC → main panel → home circuits; any surplus → meter → grid
- Grid fault → inverter rides through short dips or disconnects, per IEEE 1547 settings 3
Grid-following, grid-forming and outages
Most home inverters are grid-following. DOE explains that a grid-following inverter relies on an outside grid signal to time its switching 1. When the grid disappears, it has nothing to follow, so it stops. That is deliberate. It keeps the panels from feeding power onto lines that crews think are dead.
A grid-forming inverter makes its own signal and can run a small isolated grid, such as a home cut off from the utility by a battery gateway 1.
That is how solar-plus-battery systems keep the lights on in an outage.
DOE notes solar can charge a battery over DC or after conversion to AC, and such systems can run without grid support if designed to 1.
Storage itself is never 100% efficient, because some energy is lost converting it in and out 5.
DOE adds that small inverters ride through brief voltage or frequency disturbances but disconnect if a disturbance lasts long or is larger than normal 1.
Types of solar inverters
| Type | Where it sits | Strength | Trade-off |
|---|---|---|---|
| String inverter | One box, often near the panel | Lower cost per watt | Shade on one panel lowers the whole string 1 |
| Microinverter | Under each panel | Panels work independently | Can cost more 1 |
| String + power optimizers | Optimizer at each panel, one inverter | Panel-level tuning with one inverter | More parts on the roof |
| Hybrid (battery-ready) | One box for solar and battery | Charges a battery on the DC side | Tied to compatible batteries |
| Central inverter | Utility-scale plants | Handles very large arrays 1 | Not used on homes |
String inverter
- One inverter for many panels
- Cost-effective 1
- Weakest panel limits the string
Microinverters
- One small inverter per panel
- Shade on one panel does not drag the rest 1
- Can cost more
Source: [1]
Example: how shade changes the inverter choice
A shaded roof shows DOE’s description of string and micro behavior in practice. It shows logic, not a production estimate 1.
| Roof situation | String inverter | Microinverters |
|---|---|---|
| All panels on one south face, no shade | Works well; lower cost | Works well; may cost more |
| Chimney shades two panels each morning | Whole string drops while shaded | Only the two shaded panels drop |
| Panels split over east and west faces | Needs separate strings or optimizers | Each panel handled on its own |
| Adding a battery later | Hybrid string inverter can be battery-ready | Usually an AC-coupled battery added |
For the electrical side of adding solar, such as panel capacity and the backfed breaker, see the panel space tool.
Where you see the inverter
A string inverter is a wall box, often in the garage or beside the meter. Microinverters hide under the panels; you see their gateway box near the panel. The inverter’s AC rating appears on the quote as the system’s “AC size,” which is often lower than the panels’ DC size.
On the utility interconnection form, the inverter model and its UL 1741 certification are listed, because the utility checks it meets grid rules 3. On your monitoring app, the inverter is what reports production.
Benefits and drawbacks
What it does well
Where it falls short
- Grid-tied units shut off in outages without storage 1.
- Electronics wear out before panels do in many systems; check warranties.
- Heat reduces output; placement matters.
- Utility settings and approvals can delay start-up.
Limits
- No backup by default. Grid-tied systems need a battery and gateway to run during an outage 1.
- Clipping. When panels make more DC than the inverter’s AC rating, the extra is lost at peak hours.
- Panel capacity. The inverter’s backfed breaker must fit the panel’s busbar limits.
- Settings. Utilities can require specific settings under IEEE 1547 3.
What drives the cost
No prices in this glossary. These factors move the inverter part of a quote.
- Type. Microinverters and optimizers add parts at each panel 1.
- AC rating. Bigger systems need more inverter capacity.
- Battery-readiness. Hybrid units cost more upfront.
- Grid-support certification. UL 1741 SB-certified units may be required by your utility 3.
- Panel work. A full or old panel may need an upgrade.
- Warranty length. Inverter warranties are often shorter than panel warranties; compare terms.
How an inverter gets installed
A licensed solar installer and electrician do this work. DOE notes a certified electrician inspects the system during installation 4.
- Design the array and pick inverter type and size.
- Check panel capacity and where the inverter output ties in.
- Submit permits and the utility interconnection application.
- Install, wire and label disconnects.
- Pass inspection, get utility permission to operate, then switch on.
Upkeep
- Watch the monitoring app; a drop in output is often the first sign of an inverter fault.
- Keep wall-mounted inverters clear of storage so they can shed heat.
- Note any fault codes and send them to the installer.
- Ask about firmware updates that utilities may require.
Warning signs
A dark display, fault lights, buzzing louder than usual, scorch marks or a burning smell mean call the installer. Do not open the inverter. Panels make DC voltage whenever light hits them, even when the grid is off.
If your production falls on sunny days, the inverter or a panel-level device may have failed. Our electrical inspection page explains when a broader check makes sense.
Solar wiring stays live in daylight
Solar panels produce DC voltage whenever there is light, even with the grid down and the main breaker off. Never touch inverter or panel wiring. Leave all troubleshooting to a licensed installer.
Standards and rules
| Authority | Standard | What it requires |
|---|---|---|
| IEEE | IEEE 1547-2018 (tests in IEEE 1547.1-2020) | Ride-through, voltage and frequency support, communications 3 |
| UL | UL 1741, Supplement SB | Certifies inverters to IEEE 1547 grid-support functions 3 |
| NFPA 70 (NEC) | 2023 ed., Articles 690 and 705 | PV systems and interconnection to the premises wiring |
| Your utility | Interconnection rules and settings | Approval before the system may operate |
Solar inverter vs related devices
| Device | Converts | Main use |
|---|---|---|
| Solar inverter | Panel DC → AC | Solar systems |
| UPS | AC → battery DC → AC | Keeping devices on |
| Battery system inverter | Battery DC ↔ AC | Storage and backup |
| Transformer | AC voltage up or down | Grid and appliances |
| Generator alternator (standby unit) | Mechanical → AC | Backup power |
Myths
- Myth Solar keeps my lights on when the grid fails.
- Reality Grid-tied inverters stop in an outage unless the system is designed with storage to run alone 1.
- Myth Microinverters are always better.
- Reality They help with shade but can cost more; a string inverter can suit an open roof 1.
- Myth Inverter rules are the same everywhere.
- Reality Utilities set settings and timelines for IEEE 1547 adoption 3.
State and utility factors
States and utilities adopted IEEE 1547-2018 on different timelines; Solar Builder reported that California, Texas and New York had set or planned adoption dates, while other states had not announced plans 3. Your state’s NEC edition decides the PV wiring rules.
Choosing an inverter
For a single open roof face, a string inverter is often enough. For shade or several roof faces, consider microinverters or optimizers. If you want backup now or later, choose a design that supports a battery and a gateway.
Check your panel first. The electrification readiness tool shows whether your service has room for solar alongside other new loads.
Ask this on every quote
Ask what happens in an outage. If the answer is “nothing,” the design has no backup.
Questions about Solar Inverter
What does a solar inverter do?
It converts the direct current made by solar panels into alternating current that your home and the grid use. It also tunes the panels for the most output as light changes, matches the grid’s voltage and frequency, and decides when to ride through or disconnect during grid problems, following IEEE 1547 settings.
Do solar panels work during a power outage?
Not with a standard grid-tied inverter. It follows the grid’s signal and shuts down when the grid fails, which protects line workers. To keep power during outages, the system needs a battery and a gateway, or an inverter design that can form its own small grid while isolated from the utility.
What is the difference between a string inverter and a microinverter?
A string inverter is one box serving a row of panels, so shade or a fault on one panel lowers the whole string’s output. Microinverters sit under each panel, so each works on its own, which helps on shaded or split roofs. DOE notes microinverters can cost more.
What is a hybrid inverter?
A hybrid inverter handles both solar panels and a battery in one unit. It can charge the battery from the panels on the DC side and supply the home from either source. Hybrid units make adding storage simpler but tie you to batteries that are compatible with that inverter.
What is UL 1741 SB?
UL 1741 is the safety standard for inverters, and Supplement SB certifies that an inverter meets the grid-support functions of IEEE 1547-2018, tested under IEEE 1547.1-2020. Those functions include riding through brief disturbances and adjusting power for voltage and frequency. Many utilities now require SB-certified inverters.
How long do solar inverters last?
It depends on the model, heat and use, and the warranty is the best guide. Inverter warranties are often shorter than panel warranties, so many owners plan for an inverter replacement during the life of the panels. Compare warranty years and terms on every quote.
Why is my inverter AC size smaller than my panel DC size?
Designers often pair more panel capacity than inverter capacity because panels rarely produce their full rating. The inverter clips a little power at peak hours, but the system makes more energy over the day. The ratio of DC to AC size shows on most quotes.
Where should a solar inverter be installed?
String inverters usually mount on a wall in a garage, utility room or outside near the meter, where they can shed heat and be reached for service. Microinverters mount under the panels. The installer follows the maker’s clearances and the local code edition your state has adopted.
Do I need a permit to replace a solar inverter?
Usually, yes. Replacing an inverter changes the electrical interconnection, so most towns require a permit and inspection, and the utility may need to update its records. A licensed installer handles this and confirms the new inverter meets the utility’s current rules.
Sources
- U.S. DOE, Solar Integration: Inverters and Grid Services Basics, retrieved .
- U.S. EIA, Solar explained: Photovoltaics and electricity, retrieved .
- Solar Builder, Smart PV inverter overview: IEEE 1547-2018 and UL 1741 explained, retrieved .
- U.S. DOE, Homeowner’s Guide to Going Solar, retrieved .
- U.S. DOE, Solar Integration: Solar Energy and Storage Basics, retrieved .
Expert review
Written by the HyreElectrical Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Checked against DOE inverter and storage basics, DOE’s homeowner solar guide, EIA’s PV explainer and Solar Builder’s IEEE 1547/UL 1741 overview on 2026-10-10.
Suggest a correction. We fix errors and say what changed.