Alternative Power sources

Author

inverters

Bill Wilson

2005-07-24, 9:06 pm

Looking for a 3000 watt (or so) inverter and am trying to decide if true
sine wave is worth the price. I'm building a solar powered system for my
kitchen. It'll be used to power a refrigerator (possibly a chest freezer
conversion), and 2 chest freezers and lights and occasional electric mixer
and maybe a ceiling fan.
Is true sine wave the way to go or for starters, would modified sine be
okay?
I would like opinions please.........thanks!

2005-07-24, 9:06 pm

Bill Wilson wrote:
> Looking for a 3000 watt (or so) inverter and am trying to decide if true
> sine wave is worth the price. I'm building a solar powered system for my
> kitchen. It'll be used to power a refrigerator (possibly a chest freezer
> conversion), and 2 chest freezers and lights and occasional electric mixer
> and maybe a ceiling fan.

So all kinds of AC motors... for that, yeah, you'd be best off with
sinewave. Modified square wave (modified sinewave is a marketing term)
is best for non-motor purposes, like lighting. To be fair, I do know a
person running a refrigerator off a new mod-square inverter, and it
seems to work well.

If you're going to be running a refrigerator and two chest freezers,
though, be careful in sizing that inverter. IF they all came on at the
same time, you'd want to make sure the inverter could handle the surge.
And you might want to look into the DC ceiling fans. They are a bit
more expensive, but use a great deal less electricity.

> Is true sine wave the way to go or for starters, would modified sine be
> okay?
> I would like opinions please.........thanks!

If it were me, and in my off-grid home, it is ;-), yes, I'd say it's
worth it.
Get something modern and reputable, like say a OutBack, something like
a VFX3524 or something (a 3500 watt inverter with 24v input).

DJ

Kiwi John

2005-07-24, 9:06 pm

without a doubt
"DJ" <dj_macintyre@hotmail.com> wrote in message
news:1122175916.762909.103480@g44g2000cwa.googlegroups.com...
>
>
> Bill Wilson wrote:
>
> So all kinds of AC motors... for that, yeah, you'd be best off with
> sinewave. Modified square wave (modified sinewave is a marketing term)
> is best for non-motor purposes, like lighting. To be fair, I do know a
> person running a refrigerator off a new mod-square inverter, and it
> seems to work well.
>
> If you're going to be running a refrigerator and two chest freezers,
> though, be careful in sizing that inverter. IF they all came on at the
> same time, you'd want to make sure the inverter could handle the surge.
> And you might want to look into the DC ceiling fans. They are a bit
> more expensive, but use a great deal less electricity.
>
>
> If it were me, and in my off-grid home, it is ;-), yes, I'd say it's
> worth it.
> Get something modern and reputable, like say a OutBack, something like
> a VFX3524 or something (a 3500 watt inverter with 24v input).
>
> DJ
>

Jack Hayes

2005-07-24, 9:06 pm

"Bill Wilson" <mrbillwilson@hotmail.com> wrote in message
news:dbv00t01623@enews2.newsguy.com...
> Looking for a 3000 watt (or so) inverter and am trying to decide if true
> sine wave is worth the price. I'm building a solar powered system for my
> kitchen. It'll be used to power a refrigerator (possibly a chest freezer
> conversion), and 2 chest freezers and lights and occasional electric mixer
> and maybe a ceiling fan.
> Is true sine wave the way to go or for starters, would modified sine be
> okay?
> I would like opinions please.........thanks!
>
>

I have had no problem running a 1/3 HP water pump on a modified sine wave
over the last 10 years, but the true sine wave would be better.
More importantly with your loads I would look at setting up a system to
avoid running more than 1 freezer at a time, this will minimize peak battery
current which will result in more useable energy from your battery bank.

Jack

Vaughn

2005-07-24, 9:06 pm

Others have had better results, but my 'fridge and my square wave inverter
do not like each other.

Vaughn

JoeSixPack

2005-07-24, 9:06 pm

Scott Willing

2005-07-25, 3:21 pm

On Sat, 23 Jul 2005 21:55:38 -0500, "Bill Wilson"
<mrbillwilson@hotmail.com> wrote:

>Looking for a 3000 watt (or so) inverter and am trying to decide if true
>sine wave is worth the price. I'm building a solar powered system for my
>kitchen. It'll be used to power a refrigerator (possibly a chest freezer
>conversion), and 2 chest freezers and lights and occasional electric mixer
>and maybe a ceiling fan.
>Is true sine wave the way to go or for starters, would modified sine be
>okay?
>I would like opinions please.........thanks!
>

Aside from more efficient motor operation, also consider that with
most sine-wave inverters, you also get a high-quality, high-power,
adjustable and possibly power-factor corrected multi-stage battery
charger for replenishing batteries from the grid or a generator when
the sun hasn't been out for a while. And it's practically free since
it uses the same power components as the inverter.

The battery charger in my Outback VFX3524 is worth every bit as much
to me, if not more than, the sinewave output from the inverter.
(Caveat: I rarely run AC motors myself; if I did, I'd value the sine
output more than I do at present.)

The PFC charger in the Outback is a far friendlier load for my
generators than the non-PFC charger I was using before. One of the
gennies couldn't even maintain a steady output unless I swamped the
non-linear load characteristic of my charger with a baseboard heater
-- and even the other one would actually deliver more current to the
batteries with the swamp load in place than without. A big non-linear
load is about the worst thing a generator can see. Control options on
the Outback are quite extensive, e.g. enabling me to tailor the
maximum charger draw to the generator capability.

All this has cut my typical genny run-time from all day to a couple of
hours. Some folks might not place a lot of value in that, but I sure
do.

-=s

Windsun

2005-07-26, 2:21 pm

An AC motor will use about 20% more power with a modified sine wave than
with a true sine wave.

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"Bill Wilson" <mrbillwilson@hotmail.com> wrote in message
news:dbv00t01623@enews2.newsguy.com...
> Looking for a 3000 watt (or so) inverter and am trying to decide if true
> sine wave is worth the price. I'm building a solar powered system for my
> kitchen. It'll be used to power a refrigerator (possibly a chest freezer
> conversion), and 2 chest freezers and lights and occasional electric mixer
> and maybe a ceiling fan.
> Is true sine wave the way to go or for starters, would modified sine be
> okay?
> I would like opinions please.........thanks!
>
>

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