Solar Inverter Size Calculator
What size solar inverter do you need? Enter your panel power to see a suitable inverter size, the DC-to-AC ratio, and how much energy would be lost when the inverter reaches its limit. Use it as a first check before you speak to an installer.
For planning only. This tool gives a preliminary estimate. It is not a design, and a qualified professional must check it against the datasheets and your local electrical rules.
Your inverter size
For 6 kW of panels near Los Angeles, a 5 kW inverter gives a ratio of 1.20.
Preliminary estimate. Must be verified by a qualified professional.
- Pass: Panel-to-inverter ratio looks typical1.20 is within a common planning range.
- Pass: The inverter covers your peak load3 kW is within its 5 kW rating.
- Pass: Check your grid operator's export limitLimits vary by area, so confirm yours in writing.
What clipping looks like
The inverter flattens the top of the curve. This is a typical day. The brightest days clip more.
| Point | Panels could make | Inverter delivers |
|---|---|---|
| 00:00 | 0 | 0 |
| 01:00 | 0 | 0 |
| 02:00 | 0 | 0 |
| 03:00 | 0 | 0 |
| 04:00 | 0 | 0 |
| 05:00 | 0.02 | 0.02 |
| 06:00 | 0.54 | 0.54 |
| 07:00 | 1.59 | 1.59 |
| 08:00 | 2.66 | 2.66 |
| 09:00 | 3.59 | 3.59 |
| 10:00 | 4.27 | 4.27 |
| 11:00 | 4.61 | 4.61 |
| 12:00 | 4.6 | 4.6 |
| 13:00 | 4.22 | 4.22 |
| 14:00 | 3.53 | 3.53 |
| 15:00 | 2.6 | 2.6 |
| 16:00 | 1.55 | 1.55 |
| 17:00 | 0.53 | 0.53 |
| 18:00 | 0.02 | 0.02 |
| 19:00 | 0 | 0 |
| 20:00 | 0 | 0 |
| 21:00 | 0 | 0 |
| 22:00 | 0 | 0 |
| 23:00 | 0 | 0 |
| Inverter | Ratio | Yearly output | Clipped |
|---|---|---|---|
| 6 kW | 1.00 | 10,943 kWh | 0% |
| 5 kW | 1.20 | 10,943 kWh | 0% |
| 4 kW | 1.50 | 10,659 kWh | 2.6% |
What if?
Save this result, change any setting, and compare.
How this is calculated
DC-to-AC ratio
Panels rarely reach their full rating, so inverters are often smaller than the panels connected to them. The ratio compares the two.
DC-to-AC ratio = panel kW ÷ inverter kW
Clipping
When panels produce more than the inverter can pass, the extra is lost. We estimate this by running the solar model for your location with and without the limit.
Checks
We compare the result against common planning limits, your peak load, and your supply type. Your inverter's datasheet and your grid operator decide what is allowed.
Worked example: 6 kW of panels
At a target ratio of 1.2, 6 kW of panels needs about 5 kW, so the next common size is 5 kW.
That gives a ratio of 1.20. On typical days at the example location, clipping is about 0% of yearly output. The brightest days clip more than this model shows.
How accurate is this?
The model uses typical days for each month, so it understates clipping on the brightest days. Treat the clipping figure as a low estimate. This tool is a preliminary check, and a qualified professional must verify the design.
Common mistakes
- Assuming an inverter must match the panel rating exactly
- Ignoring the maximum DC input on the datasheet
- Forgetting grid limits on inverter size or export
- Using a grid-tied inverter's rating as a backup rating
Limits of this tool
- It does not design strings or check voltage, so use the string voltage calculator
- Inverter sizes are common examples, not specific products
- Local rules and grid operators can set lower limits
What to do next
- Check your panel strings with the string voltage calculator
- Confirm your design with a qualified installer
Frequently asked questions
What size inverter do I need for a 6 kW solar system?
Often about 5 kW, which gives a ratio of 1.2. Check your inverter's limits and your grid rules.
Can I connect more panels than the inverter rating?
Often yes, within the maker's limits. It is common because panels seldom reach their full rating.
What is a good DC-to-AC ratio?
Around 1.1 to 1.3 is common for homes. The right value depends on your climate, roof direction, and equipment.
What is inverter clipping?
It is the energy lost when panels produce more than the inverter can convert. A small amount is often acceptable.