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Solar Inverter Size Calculator

Find the right inverter rating for your home. This home inverter calculator takes the load that must run together and your solar array size, and gives the recommended inverter VA/kVA and solar inverter kW.

Inverter VA = running watts ÷ 0.8 power factor × 1.2 headroom, rounded up to the next standard size. Example: 800 W of fans, lights, fridge and TV needs 1,200 VA, so a 1,450 VA inverter. Adding a 1.5 ton AC takes most homes to about 3,500 VA. For solar, pair a 3 kW array with a 2.5 to 3 kW inverter.

Find Your Inverter Rating

Sum of appliances running together, not everything you own. Build it with the solar load calculator.
Leave 0 for a backup-only (non-solar) inverter.

Your Inverter Recommendation

–
recommended inverter rating
VA required (with headroom)–
Solar inverter rating–
Load entered–
Rating guide only: motor loads and start-up surges need checking against the actual datasheet. A local solar contractor can confirm the inverter size and price for your home.

Built and maintained by Solar Calculators Pro · Power factor and headroom used for inverter sizing

Inverter Sizes for Typical Indian Home Loads

Simultaneous LoadExamplesRecommended Inverter
up to 500 WFans, lights, TV, router850 VA
500 – 900 W+ fridge, computer1,450 VA
900 – 1,600 W+ washing machine or 1 ton AC2,500 VA
1,600 – 2,300 W+ 1.5 ton AC3,500 VA
2,300 – 3,300 WTwo ACs or AC + geyser5 kVA
3,300 – 6,500 WLarge home, multiple ACs7.5 – 10 kVA

Motors and compressors (ACs, pumps, fridges) draw 2 to 3 times their running watts for a moment at startup. The 20% headroom built into this calculator absorbs normal starts; homes starting two big motors together should step one rating higher.

Backup Inverter VA vs Solar Inverter kW

Two different ratings get called "inverter size". The backup rating (VA/kVA) is how much load the inverter can run at once, sized from your simultaneous load at 0.8 power factor. The solar rating (kW) is how much panel power it can convert, normally matched so the array is 1.0 to 1.2 times the inverter kW (a DC/AC ratio that sacrifices nothing in practice, since panels rarely hit nameplate). A hybrid inverter carries both ratings; this calculator reports each separately so you can check a quote line by line.

Count Simultaneous Load, Not Total Load

The single most common inverter sizing error is adding up every appliance you own. The inverter only needs to carry what runs at the same moment. A realistic evening peak for a mid-size home: two fans, six lights, fridge, TV, router and one AC: about 2,100W, even though the house "owns" 6 kW of appliances. Two refinements make the number robust: include the fridge always (it decides for itself when to run), and pick the worst normal moment, not a hypothetical everything-on scenario. If you skipped it, build the list in the solar load calculator; its connected-load figure feeds this tool directly.

A Kochi Home With 4kW of Solar

A Kochi household peaks at 2,100W simultaneous load and is installing a 4kW panel array. Backup maths: 2,100 ÷ 0.8 power factor × 1.2 headroom = 3,150 VA, so the calculator recommends a 3,500 VA (3.5 kVA) unit. Solar maths: a 4kW array pairs with a 3.5 kW hybrid inverter (a healthy 1.14 DC/AC ratio). One 3.5 kVA hybrid machine satisfies both jobs here, which is the tidy outcome; when the two numbers diverge, the larger requirement wins.

Reading an Inverter Datasheet Before You Buy

  • Continuous vs surge rating. The 3,500 VA continuous line matters; the "7,000 VA surge for 20ms" line is for motor starts, not for running more load.
  • MPPT voltage window. Your string's voltage must sit inside it across seasons; installers handle this, but the range on the sheet is worth eyeballing for future panel additions.
  • Battery voltage and type support. A 48V LiFePO4-ready unit with a communication port (BMS talk) future-proofs a later battery purchase.
  • Efficiency curve, not peak. 97% peak efficiency at full load means little at your usual 30% load; the flat-curve unit wastes less all day.

Inverter Choices That Backfire

  • Buying VA as if it were watts. A 2,500 VA inverter carries about 2,000W of mixed home load; the 0.8 power factor is not fine print, it is the spec.
  • Massive oversizing "for the future". A 10 kVA unit idling on a 1 kW evening load burns its own standby power and cost double; one size of headroom is plenty.
  • Ignoring the DC/AC ratio the other way. A 5kW inverter under a 3kW array wastes inverter money; arrays should meet or slightly exceed inverter rating.
  • Two big motor starts together. If the borewell pump and AC can start in the same minute, step one rating up or interlock the pump; surge stacking trips undersized units.

Power Factor, Headroom and Standard Ratings

Required VA = Load (W) ÷ 0.8 power factor × 1.2 headroom
Recommended = next standard rating (850 / 1,450 / 2,500 / 3,500 VA, 5 / 7.5 / 10 kVA…)
Solar inverter kW = Array kW ÷ 1.1 (typical DC/AC ratio), rounded to 0.5 kW

Inverter settings

  • Power factor: 0.8, typical for mixed home loads
  • Headroom: 20% for motor starts and future additions
  • Ratings list: standard Indian home inverter sizes from 850 VA to 15 kVA

Inverter Size FAQs

What size inverter do I need for my home?+
Add up the watts of everything that runs at the same time, divide by 0.8 power factor and add 20% headroom. A typical home running fans, lights, fridge, TV and one 1.5 ton AC lands at about 3,500 VA; without the AC, 1,450 to 2,500 VA covers it.
What inverter size is right for a 3kW solar system?+
A 3 kW array pairs with a 2.5 to 3 kW solar or hybrid inverter (DC/AC ratio 1.0 to 1.2). If it is a hybrid system, also check the backup VA covers your power-cut load; the two ratings are independent.
What is the difference between VA and watts for inverters?+
Watts are real power; VA is apparent power, and inverters are rated in VA. Home loads average a 0.8 power factor, so a 2,500 VA inverter supports about 2,000 W of appliances. Ignoring this is the most common cause of undersized inverters.
Can I run a 1.5 ton AC on an inverter?+
Yes, on 3,500 VA or larger with a battery bank that can supply the current. An inverter AC is strongly preferred as its soft start avoids the heavy surge of a fixed-speed compressor.
Is a bigger inverter always better?+
No. Oversized inverters idle at lower efficiency and cost more upfront. Size to your realistic simultaneous load with one step of headroom for growth; the panels, not the inverter, decide how much energy you generate.
Can my solar array be bigger than the inverter rating?+
Yes, up to about 1.2 times the inverter kW is standard practice. Panels rarely deliver nameplate power on hot Indian roofs, so mild oversizing (called a higher DC/AC ratio) captures more morning and evening energy with negligible clipping.
Can one inverter handle both solar and battery backup?+
Yes: that is a hybrid inverter. It carries two independent ratings: solar kW it can convert and VA it can supply from the battery. Check each against your array and your simultaneous load; this calculator reports both numbers separately for exactly that reason.
What happens if my inverter is too small for my panels?+
The inverter clips output on bright middays, flattening the generation curve. Up to a 1.2 DC/AC ratio the annual loss is negligible; beyond about 1.3 you are throwing away real units and should size the inverter up.
How do I calculate inverter capacity and battery for my home?+
Inverter: add the watts of appliances used together, divide by 0.8 and add 20% headroom. Battery: backup watts × hours ÷ 1,000 ÷ 0.85, then divide by the usable depth of discharge (0.5 for lead-acid, 0.85 for lithium). For 800 W over 4 hours, that is a 1,450 VA inverter with about 4.4 kWh of lithium or 7.5 kWh of lead-acid battery.
How many solar panels can I connect to my inverter?+
For a grid-tied or hybrid solar inverter, the panel array can be up to about 1.2 times the inverter's kW rating: a 3 kW inverter takes up to about 3.6 kW, for example six 550 to 600 W panels. For a home inverter with a built-in solar charge controller, the limit is the maximum solar input (watts and voltage) printed on its datasheet.
How many solar panels do I need for a 2 kVA or 3 kVA inverter?+
The kVA rating tells you how much load the inverter can run at once, not how many panels it needs. Size the panels from the units you want to generate each day, then check that the array stays within the inverter's maximum solar input on its datasheet.

Match the Inverter to the Rest