inverter

HI all from British Columbia, what im working on is a 600 watt aray with 6-225 amp h 6 volt deep cycle battries , all i want to power is my fridge, freezer, and sat dish, i need aprox 2100 wh per day, what size inverter do you think i should go with a 2000 or 3000w. thanks

bulldog said:

HI all from British Columbia, what im working on is a 600 watt aray with 6-225 amp h 6 volt deep cycle battries , all i want to power is my fridge, freezer, and sat dish, i need aprox 2100 wh per day, what size inverter do you think i should go with a 2000 or 3000w. thanks

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Inverter is determined by power required.

For optimal efficiency:

3X your typical run power.

Must also be able to handle 5X the surge of any motors (fridge and freezer compressor) UNLESS those motors are "inverter" type, i.e., they have built-in soft start.

Not sure if you know but not all inverters are equal and most inverter advertising from online retailers like Amazon and AliExpress are woefully inaccurate and often misleading. IMO, whether you can afford one or not, at least look at the specs of expensive high quality inverters such as from Victron or Samlex and others to learn what they deem as features, vs. most of the crap you will find on Amazon. Will Prowse on YouTube also has a bunch of inverter videos and reviews, that watched repeatedly will help you figure out what they are about and what features are useful to you and what you can afford.

You may also benefit from searching the forums on past inverter threads, as for: modified sine wave inverter, pure sine wave inverter, inverter surge load, low frequency inverter, high frequency inverter, inverter / charger, All in One (AiO) inverters, plus other things that you will read in the discussions, such as inverter idle current or draw, eco mode and how that works or doesn't, generator auto start if needed, inverter power factor and so on. All of this and more and "what inverter should I buy" has been discussed before and can be found in these forums. Go SLOW, do not impulse buy and budget to pay more for a quality inverter/charger or even buy an older one used. Mine is 20 years old and works better and does so many things better than many new "inverters" available today, especially new low cost inverters that may not have a good track record.

Also read and perform Sunshine_Eggo's Energy Audit info in the Resources section.

Not MY energy audit. @FilterGuy get's that credit.

I would also recommend some of the lesser brands like Giandel and WZRELB ("reliable").

One thing to watch for is "surge" rating.

You see a lightweight 2000W inverter that says 4000W surge, it's not real. Sure... it can handle 4000W for about 20 milliseconds, but not the handful of seconds an electric motor is required to start.

If you're running a lightweight inverter with motors, make sure the max continuous rating of the inverter is 5X the continuous run power of the motor.

As an example, my first inverter:


Is rated for 4000W surge. I didn't expect it to work, but I have a 3/4hp jet pump that draws 800W run... that's about 4000W surge... Nope... didn't work.

yes i intend to purchase only quality brand products, the question is with the system as outlined as above which inverter would suit best a 2000 or 3000 watt

bulldog said:

yes i intend to purchase only quality brand products, the question is with the system as outlined as above which inverter would suit best a 2000 or 3000 watt

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As you may have gathered from my response, the answer depends on your loads. Listing your devices is not your loads.

the fridge and freezer both draw 6 amps and the sat dish will draw 2.5 amps is that what you mean by the loads

bulldog said:

the fridge and freezer both draw 6 amps and the sat dish will draw 2.5 amps is that what you mean by the loads

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That's a start. 6A at 12V? 120VAC?

Power = volts * amps.

A great way to get power numbers is to get a kill-a-watt or equivalent device between the 120VAC outlet and your appliance. It will report Watts (VA) and kWh consumption as well as letting you know your household voltage and frequency.

What DC voltage are your batteries set up for? 12 volt, 24 volt, 48 volt? You also need an inverter set up for that voltage and to put out 120 volts AC from your batteries? Do you want the inverter to also have a battery charger function? What is your budget? You can't really go wrong with Victron Inverter/Chargers or Victron Inverter if you want pure sine wave? I've got a friend in BC who has a 24 volt, 2,400 Watt Trace 2424 DW Modified Sine Wave for Sale. Very durable, heavy, low frequency with a built in charger function.

The larger the inverter the larger the amount of energy it wastes around the clock even when there is no load on it.

For that reason I always select the smallest needed for the job, especially on a small system.

But that brings up the larger issue here- you need way more panels than the 600w you're currently going with.

Leeds said:

The larger the inverter the larger the amount of energy it wastes around the clock even when there is no load on it.

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Depends doesn't it? Some inverters have really high efficiency inversion and most good ones have an adjustable Eco or Search mode. My 4000 watt 24 Volt low frequency 20 year old inverter, has a search function that just sips barely any watts and that can be greatly adjusted in search pulses over time and even in standard mode, the manual lists it using only 16 watts for inverting or in idle / On. Read today of a similar Samlex that uses even less than that. Lots of variables. Most small inverters may also be less efficient, so there are those losses not calculated and they have far fewer functions. But whatever works.

E. Cho said:

Depends doesn't it? Some inverters have really high efficiency inversion and most good ones have an adjustable Eco or Search mode.

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If you need ANY power at all ECO/search modes are generally useless. The fridge thermostats may not function at all when inverter is on ECO or search.

E. Cho said:

My 4000 watt 24 Volt low frequency 20 year old inverter, has a search function that just sips barely any watts and that can be greatly adjusted in search pulses over time

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This is a pretty rare capability.

sunshine_eggo said:

If you need ANY power at all ECO/search modes are generally useless. The fridge thermostats may not function at all when inverter is on ECO or search.



This is a pretty rare capability.

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My inverter/charger will not wake up by my ac,heat,fridge or computer on eco mode.

Yes the search mode needs trial and error with appliances or loads but it is adjustable. It worked great with lights over 8 watts at a more frequent search pulse. I used it that way for many years before I had enough battery and solar recharging power to just leave it on 24/7. It's a feature that small systems could use for overnight and many low cost inverters don't have.