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solar powered fridge? [message #113134] Wed, 26 January 2011 04:44 Go to next message
hertfordnc is currently offline  hertfordnc   United States
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
Senior Member
The Revcon fridge works fine but I'm working on my little scotty trailer and i had an idea that needs testing.

How much solar would it take to sustain a regular 10 cubic foot house fridge?

I'm thinking 200 watts, charging a battery, through an inverter?

Then maybe you hack the fridge's thermostat with a relay so the inverter is cut off between cycles?

It seems to me if you had to replace a two-way Norcold for $1000 you could do just as well putting that money into a system like this.

Is my math wrong? If the fridge draws 1-2 amps and is only on 25% of the time, then a deep-cycle could run it for a while. Would 150 watts of solar be enough to maintain the battery?












Dave & Ellen Silva Hertford, NC 76 Birchaven, 1-ton and other stuff Currently planning the Great american Road Trip Summer 2021 It's gonna take a lot of Adderall to get this thing right.
Re: [GMCnet] solar powered fridge? [message #113138 is a reply to message #113134] Wed, 26 January 2011 07:15 Go to previous messageGo to next message
Byron Songer is currently offline  Byron Songer   United States
Messages: 1912
Registered: August 2007
Location: Louisville, KY
Karma: -2
Senior Member

Let's see.

If it's warmer weather and the fridge needs to kick on at night and there's
no sun to power the solar, will it work?

Seems to me you'd be better off to just plan to park where you have power.

Thinking outside the box.

Byron

dave silva wrote:

>
>
> The Revcon fridge works fine but I'm working on my little scotty trailer and
> i had an idea that needs testing.
>
> How much solar would it take to sustain a regular 10 cubic foot house fridge?
>
> I'm thinking 200 watts, charging a battery, through an inverter?
>
> Then maybe you hack the fridge's thermostat with a relay so the inverter is
> cut off between cycles?
>
> It seems to me if you had to replace a two-way Norcold for $1000 you could do
> just as well putting that money into a system like this.
>
> Is my math wrong? If the fridge draws 1-2 amps and is only on 25% of the time,
> then a deep-cycle could run it for a while. Would 150 watts of solar be
> enough to maintain the battery?
>
>
>
>
>
>
>
>
>
>


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-- Byron Songer
Full-timing to enjoy the USA
Former owner but still an admirer
GMC paint schemes at -
http://www.songerconsulting.net
Re: [GMCnet] solar powered fridge? [message #113143 is a reply to message #113138] Wed, 26 January 2011 07:51 Go to previous messageGo to next message
hertfordnc is currently offline  hertfordnc   United States
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
Senior Member
Byron Songer wrote on Wed, 26 January 2011 07:15

Let's see.

If it's warmer weather and the fridge needs to kick on at night and there's
no sun to power the solar, will it work?




That's where the battery comes in.

The question is, how much battery will it take and how much loss is there throguh an inverter?

And, if you are in the market for a new fridge, would the $1000 or so be better spent on something like htis, which would also augment your charging system.




Dave & Ellen Silva Hertford, NC 76 Birchaven, 1-ton and other stuff Currently planning the Great american Road Trip Summer 2021 It's gonna take a lot of Adderall to get this thing right.

[Updated on: Wed, 26 January 2011 07:53]

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Re: [GMCnet] solar powered fridge? [message #113144 is a reply to message #113138] Wed, 26 January 2011 07:59 Go to previous messageGo to next message
gmcrv1 is currently offline  gmcrv1   United States
Messages: 839
Registered: August 2007
Location: Memphis
Karma: -1
Senior Member
Being a rookie with the GMCs but having played with solar a little bit, as
Byron mentioned, warmer weather and of course the opening and closing cycles
of the door are the two power robbers. Others have mentioned that the 12
volt side of the fridge is not as efficient as running 110v. If you have to
have really cold beer go where you have a 110v source - or - if you're like
the British, try the 12v solar and see what happens. I'm working on a small
solar assist for the 12 volt side. I have replaced most of the interior
lighting with LEDs and the electrical demand will be significantly lower
then using the old filament bulbs. I've not looked at the power demands for
the 12v side of the fridge.

I found under cabinet LED lighting in a 3 x 3 LED array at Lowe's. They use
0.175 amps @12 volts per module each module replaces one filament bulb.
Each 1141 filament bulb consumes 1.44 amps. Do the math - about a 90%
reduction in demand. I did use 3 modules over the kitchen counter for
better lighting. I would say these mods give off approximately 85-90% of
the light compared to conventional bulbs.

Thinking out of the fridge.

Tom Eckert N2VWN
73 Glacier
Oakland, TN





On Wed, Jan 26, 2011 at 7:15 AM, Byron Songer
<bsonger@songerconsulting.net>wrote:

> Let's see.
>
> If it's warmer weather and the fridge needs to kick on at night and there's
> no sun to power the solar, will it work?
>
> Seems to me you'd be better off to just plan to park where you have power.
>
> Thinking outside the box.
>
> Byron
>
> dave silva wrote:
>
> >
> >
> > The Revcon fridge works fine but I'm working on my little scotty trailer
> and
> > i had an idea that needs testing.
> >
> > How much solar would it take to sustain a regular 10 cubic foot house
> fridge?
> >
> > I'm thinking 200 watts, charging a battery, through an inverter?
> >
> > Then maybe you hack the fridge's thermostat with a relay so the inverter
> is
> > cut off between cycles?
> >
> > It seems to me if you had to replace a two-way Norcold for $1000 you
> could do
> > just as well putting that money into a system like this.
> >
> > Is my math wrong? If the fridge draws 1-2 amps and is only on 25% of the
> time,
> > then a deep-cycle could run it for a while. Would 150 watts of solar be
> > enough to maintain the battery?
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
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List Information and Subscription Options:
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Re: [GMCnet] solar powered fridge? [message #113146 is a reply to message #113144] Wed, 26 January 2011 08:08 Go to previous messageGo to next message
k2gkk is currently offline  k2gkk   United States
Messages: 4452
Registered: November 2009
Karma: -8
Senior Member

The Vitrifrigo refrigerators such as the one I
have in my boat, actually operate on 12 and/or
24 Volts (nominal). They are made to run on
24V but will also switch automatically to 12V
when that is what is supplied. To operate on
120V AC, the fridge includes a converter to
supply 24V DC which operates a little bit more
efficiently than when on 12V.

When the compressor is running, they draw
around 4.1 Amps, which amounts to very close to
50 Watts. I would say a 200 Watt solar system
could easily supply enough charge to a reasonably
sized battery to do just fine.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ex-Palm Beach, 76 ~ ~ ~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~



----------------------------------------
> Date: Wed, 26 Jan 2011 07:59:38 -0600
> From: gmcrv1@gmail.com
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] solar powered fridge?
>
> Being a rookie with the GMCs but having played with solar a little bit, as
> Byron mentioned, warmer weather and of course the opening and closing cycles
> of the door are the two power robbers. Others have mentioned that the 12
> volt side of the fridge is not as efficient as running 110v. If you have to
> have really cold beer go where you have a 110v source - or - if you're like
> the British, try the 12v solar and see what happens. I'm working on a small
> solar assist for the 12 volt side. I have replaced most of the interior
> lighting with LEDs and the electrical demand will be significantly lower
> then using the old filament bulbs. I've not looked at the power demands for
> the 12v side of the fridge.
>
> I found under cabinet LED lighting in a 3 x 3 LED array at Lowe's. They use
> 0.175 amps @12 volts per module each module replaces one filament bulb.
> Each 1141 filament bulb consumes 1.44 amps. Do the math - about a 90%
> reduction in demand. I did use 3 modules over the kitchen counter for
> better lighting. I would say these mods give off approximately 85-90% of
> the light compared to conventional bulbs.
>
> Thinking out of the fridge.
>
> Tom Eckert N2VWN
> 73 Glacier
> Oakland, TN
>
>
>
>
>
> On Wed, Jan 26, 2011 at 7:15 AM, Byron Songer
> wrote:
>
> > Let's see.
> >
> > If it's warmer weather and the fridge needs to kick on at night and there's
> > no sun to power the solar, will it work?
> >
> > Seems to me you'd be better off to just plan to park where you have power.
> >
> > Thinking outside the box.
> >
> > Byron
> >
> > dave silva wrote:
> >
> > >
> > >
> > > The Revcon fridge works fine but I'm working on my little scotty trailer
> > and
> > > i had an idea that needs testing.
> > >
> > > How much solar would it take to sustain a regular 10 cubic foot house
> > fridge?
> > >
> > > I'm thinking 200 watts, charging a battery, through an inverter?
> > >
> > > Then maybe you hack the fridge's thermostat with a relay so the inverter
> > is
> > > cut off between cycles?
> > >
> > > It seems to me if you had to replace a two-way Norcold for $1000 you
> > could do
> > > just as well putting that money into a system like this.
> > >
> > > Is my math wrong? If the fridge draws 1-2 amps and is only on 25% of the
> > time,
> > > then a deep-cycle could run it for a while. Would 150 watts of solar be
> > > enough to maintain the battery?
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Re: [GMCnet] solar powered fridge? [message #113151 is a reply to message #113146] Wed, 26 January 2011 08:36 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
According to a Dometic service manual covering most of their 3-way
refrigerators, the DC heating element can be operated at 9.6 to 22 VDC,
consuming a nominal 215 W @ 12 VDC.

In the automatic source selection mode, the battery voltage must stay above
12.8 VDC for DC operation; an override mode allows total battery depletion.

Comparing compression vs adsorption refrigeration is the proverbial apples
vs strawberries (did I get that right?) situation.

Ken H.


On Wed, Jan 26, 2011 at 9:08 AM, D C *Mac* Macdonald <k2gkk@hotmail.com>wrote:

>
> The Vitrifrigo refrigerators such as the one I
> have in my boat, actually operate on 12 and/or
> 24 Volts (nominal). They are made to run on
> 24V but will also switch automatically to 12V
> when that is what is supplied. To operate on
> 120V AC, the fridge includes a converter to
> supply 24V DC which operates a little bit more
> efficiently than when on 12V.
>
> When the compressor is running, they draw
> around 4.1 Amps, which amounts to very close to
> 50 Watts. I would say a 200 Watt solar system
> could easily supply enough charge to a reasonably
> sized battery to do just fine.
>
> ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
> ~~ ~ D C "Mac" Macdonald ~ ~~
> ~ ~ Amateur Radio - K2GKK ~ ~
> ~ ~ USAF and FAA, Retired ~ ~
> ~ ~ ~ Oklahoma City, OK ~ ~ ~
> ~~ ~ ~ "The Money Pit" ~ ~ ~~
> ~ ~ ~ ex-Palm Beach, 76 ~ ~ ~
> ~ www.gmcmhphotos.com/okclb ~
> ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
>
>
>
> ----------------------------------------
> > Date: Wed, 26 Jan 2011 07:59:38 -0600
> > From: gmcrv1@gmail.com
> > To: gmclist@temp.gmcnet.org
> > Subject: Re: [GMCnet] solar powered fridge?
> >
> > Being a rookie with the GMCs but having played with solar a little bit,
> as
> > Byron mentioned, warmer weather and of course the opening and closing
> cycles
> > of the door are the two power robbers. Others have mentioned that the 12
> > volt side of the fridge is not as efficient as running 110v. If you have
> to
> > have really cold beer go where you have a 110v source - or - if you're
> like
> > the British, try the 12v solar and see what happens. I'm working on a
> small
> > solar assist for the 12 volt side. I have replaced most of the interior
> > lighting with LEDs and the electrical demand will be significantly lower
> > then using the old filament bulbs. I've not looked at the power demands
> for
> > the 12v side of the fridge.
> >
> > I found under cabinet LED lighting in a 3 x 3 LED array at Lowe's. They
> use
> > 0.175 amps @12 volts per module each module replaces one filament bulb.
> > Each 1141 filament bulb consumes 1.44 amps. Do the math - about a 90%
> > reduction in demand. I did use 3 modules over the kitchen counter for
> > better lighting. I would say these mods give off approximately 85-90% of
> > the light compared to conventional bulbs.
> >
> > Thinking out of the fridge.
> >
> > Tom Eckert N2VWN
> > 73 Glacier
> > Oakland, TN
> >
> >
> >
> >
> >
> > On Wed, Jan 26, 2011 at 7:15 AM, Byron Songer
> > wrote:
> >
> > > Let's see.
> > >
> > > If it's warmer weather and the fridge needs to kick on at night and
> there's
> > > no sun to power the solar, will it work?
> > >
> > > Seems to me you'd be better off to just plan to park where you have
> power.
> > >
> > > Thinking outside the box.
> > >
> > > Byron
> > >
> > > dave silva wrote:
> > >
> > > >
> > > >
> > > > The Revcon fridge works fine but I'm working on my little scotty
> trailer
> > > and
> > > > i had an idea that needs testing.
> > > >
> > > > How much solar would it take to sustain a regular 10 cubic foot house
> > > fridge?
> > > >
> > > > I'm thinking 200 watts, charging a battery, through an inverter?
> > > >
> > > > Then maybe you hack the fridge's thermostat with a relay so the
> inverter
> > > is
> > > > cut off between cycles?
> > > >
> > > > It seems to me if you had to replace a two-way Norcold for $1000 you
> > > could do
> > > > just as well putting that money into a system like this.
> > > >
> > > > Is my math wrong? If the fridge draws 1-2 amps and is only on 25% of
> the
> > > time,
> > > > then a deep-cycle could run it for a while. Would 150 watts of solar
> be
> > > > enough to maintain the battery?
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist



Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
'off the grid' fridges [message #113152 is a reply to message #113146] Wed, 26 January 2011 08:40 Go to previous messageGo to next message
bukzin is currently offline  bukzin   United States
Messages: 840
Registered: April 2004
Location: North California
Karma: 0
Senior Member
This may be of some interest.


http://www.realgoods.com/p2p/search/searchresults.do?method=view&search=basic&keyword=fridge&sortby=bestSellers&page=1


Bukzin
1977 Palm Beach
Re: [GMCnet] solar powered fridge? [message #113153 is a reply to message #113146] Wed, 26 January 2011 08:48 Go to previous messageGo to next message
hertfordnc is currently offline  hertfordnc   United States
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
Senior Member
OK, one more time....

I am talking about a conventional apartment size reefer from Lowes for $200.

Powered by an inverter connected to a battery and replenished by a 150 watt solar panel.


Solar panels have gotten a lot cheaper but RV reefers have not, so maybe the power requirements need to be revisited.

A three way fridge uses a lot more electricity in either electric mode than a conventional AC fridge.

The sticker on the dorm fridge i removed from the Revcon says it draws 1 amp when running and uses 27 KW per month. That assumes a room temerture outside environment.


If the solar panel can replenish the battery after a long hot night then this system would be an alternative to spending a $1000 on a two-way Dometic or Norcold.

The solar panel and the inverter would bring the cost up to the same $1000 or so but if it worked then i think it would be better.

The conventional fridge is a lot lighter, and cheap to replace.

If you don't need Air conditioning then you could dry camp for a long time with very little energy use.

If you do need AC then the load from the fridge doesn't really matter.


Dave & Ellen Silva Hertford, NC 76 Birchaven, 1-ton and other stuff Currently planning the Great american Road Trip Summer 2021 It's gonna take a lot of Adderall to get this thing right.

[Updated on: Wed, 26 January 2011 08:54]

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Re: [GMCnet] solar powered fridge? [message #113155 is a reply to message #113153] Wed, 26 January 2011 09:01 Go to previous messageGo to next message
k2gkk is currently offline  k2gkk   United States
Messages: 4452
Registered: November 2009
Karma: -8
Senior Member

Hi, Dave.

Go to Lowe's (or equivalent) and look on the
fridge data plate to determine the power draw
for a fridge of interest.

To be reasonably safe as to the draw, add at
least 50% to that power draw and go from there
to find a reasonable approximation of the
actual power draw needed from a solar system
and inverter. Remember that your inverter
MIGHT be 80% efficient and you need to add
at least 25% to what you think you need, just
to make up for THAT inverter inefficiency.

I have a Kenmore "student" size fridge on our
dock and its performance is BARELY adequate
to keep beverages cold in the summer, even
though it is under cover (no direct sun)!

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ex-Palm Beach, 76 ~ ~ ~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~



----------------------------------------
> To: gmclist@temp.gmcnet.org
> From: david.j.silva@uscg.mil
> Date: Wed, 26 Jan 2011 08:48:52 -0600
> Subject: Re: [GMCnet] solar powered fridge?
>
>
>
> OK, one more time....
>
> I am talking about a conventional apartment size reefer from Lowes for $200.
>
> Powered by an inverter connected to a battery and replenished by a 150 watt solar panel.
>
> If the solar panel can replenish the battery after a long hot night then this system would be an alternative to spending a $1000 on a two-way Dometic or Norcold.
>
> The solar panel and the inverter would bring the cost up to the same $1000 or so but if it worked then i think it would be better.
>
> The conventional fridge is a lot lighter, and cheap to replace.
>
> If you don't need Air conditioning then you could dry camp for a long time with very little energy use.
>
> If you do need AC then the load from the fridge doesn't really matter.
> --
> Dave & Ellen Silva
>
>
> Happy owners of a 1972 Flatnose Revcon
> Here by the generosity of the GMC community
> http://www.davesilva.com/revcon
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Re: [GMCnet] solar powered fridge? [message #113166 is a reply to message #113153] Wed, 26 January 2011 10:42 Go to previous messageGo to next message
Gary Worobec is currently offline  Gary Worobec   United States
Messages: 867
Registered: May 2005
Karma: -1
Senior Member
Dave,
I would not recommend this. Most under counter fridges are motor/compressor
powered at about 1/3 horsepower which equals about 200 watts @ 110 VOLTS.
This means you will need about 16 amps of 12 volt to run it. Considering a
150 watt solar array will only get you about 7 amps average at the best of
conditions you will be in the negative. This does not even take into account
the losses in the inverter. Since these fridges are not really well
insulated they do run more than normal so within a day or so I think you
will have some issues.

With solar panels you need to take into account the angle they will be
mounted and it's usually flat in our case unless you want to be going up and
down the coach ladder all the time to adjust for sun arc and angle and also
the dust and dirt factor. A layer of dust on the panels reduces the
efficiency more that you would think. As a matter of fact the first person
to invent a system for automatic washing of ground based solar panel
"fields" is going to make a ton of money. Some are working on it but no real
solutions as yet. Just the old squeegee and a bucket.

Thanks

Gary and Joanne Worobec
1973 GMC Glacier
Anza, CA




----- Original Message -----
From: "dave silva" <david.j.silva@uscg.mil>
To: <gmclist@temp.gmcnet.org>
Sent: Wednesday, January 26, 2011 6:48 AM
Subject: Re: [GMCnet] solar powered fridge?


>
>
> OK, one more time....
>
> I am talking about a conventional apartment size reefer from Lowes for
> $200.
>
> Powered by an inverter connected to a battery and replenished by a 150
> watt solar panel.
>
> If the solar panel can replenish the battery after a long hot night then
> this system would be an alternative to spending a $1000 on a two-way
> Dometic or Norcold.
>
> The solar panel and the inverter would bring the cost up to the same $1000
> or so but if it worked then i think it would be better.
>
> The conventional fridge is a lot lighter, and cheap to replace.
>
> If you don't need Air conditioning then you could dry camp for a long
> time with very little energy use.
>
> If you do need AC then the load from the fridge doesn't really matter.
> --
> Dave & Ellen Silva
>
>
> Happy owners of a 1972 Flatnose Revcon
> Here by the generosity of the GMC community
> http://www.davesilva.com/revcon
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Re: [GMCnet] solar powered fridge? [message #113167 is a reply to message #113166] Wed, 26 January 2011 10:55 Go to previous messageGo to next message
Mr ERFisher is currently offline  Mr ERFisher   United States
Messages: 7117
Registered: August 2005
Karma: 2
Senior Member
Great post Gary

And

In orgn the sun don't shine;)

Gene
Sent from McDonalds






On Jan 26, 2011, at 8:42 AM, "Gary Worobec" <gtw5@earthlink.net> wrote:

> Dave,
> I would not recommend this. Most under counter fridges are motor/compressor
> powered at about 1/3 horsepower which equals about 200 watts @ 110 VOLTS.
> This means you will need about 16 amps of 12 volt to run it. Considering a
> 150 watt solar array will only get you about 7 amps average at the best of
> conditions you will be in the negative. This does not even take into account
> the losses in the inverter. Since these fridges are not really well
> insulated they do run more than normal so within a day or so I think you
> will have some issues.
>
> With solar panels you need to take into account the angle they will be
> mounted and it's usually flat in our case unless you want to be going up and
> down the coach ladder all the time to adjust for sun arc and angle and also
> the dust and dirt factor. A layer of dust on the panels reduces the
> efficiency more that you would think. As a matter of fact the first person
> to invent a system for automatic washing of ground based solar panel
> "fields" is going to make a ton of money. Some are working on it but no real
> solutions as yet. Just the old squeegee and a bucket.
>
> Thanks
>
> Gary and Joanne Worobec
> 1973 GMC Glacier
> Anza, CA
>
>
>
>
> ----- Original Message -----
> From: "dave silva" <david.j.silva@uscg.mil>
> To: <gmclist@temp.gmcnet.org>
> Sent: Wednesday, January 26, 2011 6:48 AM
> Subject: Re: [GMCnet] solar powered fridge?
>
>
>>
>>
>> OK, one more time....
>>
>> I am talking about a conventional apartment size reefer from Lowes for
>> $200.
>>
>> Powered by an inverter connected to a battery and replenished by a 150
>> watt solar panel.
>>
>> If the solar panel can replenish the battery after a long hot night then
>> this system would be an alternative to spending a $1000 on a two-way
>> Dometic or Norcold.
>>
>> The solar panel and the inverter would bring the cost up to the same $1000
>> or so but if it worked then i think it would be better.
>>
>> The conventional fridge is a lot lighter, and cheap to replace.
>>
>> If you don't need Air conditioning then you could dry camp for a long
>> time with very little energy use.
>>
>> If you do need AC then the load from the fridge doesn't really matter.
>> --
>> Dave & Ellen Silva
>>
>>
>> Happy owners of a 1972 Flatnose Revcon
>> Here by the generosity of the GMC community
>> http://www.davesilva.com/revcon
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
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Re: solar powered fridge? [message #113168 is a reply to message #113134] Wed, 26 January 2011 11:44 Go to previous messageGo to next message
idrob is currently offline  idrob   United States
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
Senior Member
hertfordnc wrote on Wed, 26 January 2011 02:44

T

How much solar would it take to sustain a regular 10 cubic foot house fridge?

I'm thinking 200 watts, charging a battery, through an inverter?

snip...

Would 150 watts of solar be enough to maintain the battery?




A subject near and dear to my heart.

1. Look at the yellow hang tag on the refrigerator you are considering. Most of the small 120 volt ones are quite inefficient. I think you will find a number of about 340 Kwh a year. 340/365 days a year = .931 kw per day you will be using. Since the inverter/battery loss will be aproximately 25% total, you will need to replace the 931 watts with more solar. 931/.75 = 1242 watts solar input needed.

2. The solar panel, rated at say 200 watts, will only produce that under ideal conditions, full sunshine, directly facing the sun, etc. Under real life conditions, you may get 150 watts out of it on average, for maybe at best 5 hours a day. 150 x 5 = 750 watts of charge. Probably less.

3. 1242 watts needed and 750 watts of charge. The remainder needs to be provided by the battery.

I think you can see the problem.

How to change it:

1. Find a more efficient refrigerator (good luck, the inexpensive ones are just not efficient. Small does not equal low energy use I have found).

2. Add more solar panel capacity.

The subject is a lot more complex than it appears. There are a lot of variables in energy use, refrigerator efficiency, charge efficeincy, and so on. The math will help give you ballpark ideas however. The bottom line is that NO, a 200 watt panel will not sustain, over time, a small household type refrigerator.


Rob Allen
former owner of '76 x-PB
Re: [GMCnet] solar powered fridge? [message #113202 is a reply to message #113153] Wed, 26 January 2011 16:56 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
Senior Member
Dave,

Your question got me to thinking so I did some checking and so did some
checking and found this:

1) Lowes fridge: $219

http://www.lowes.com/ProductDisplay?partNumber=326297-47224-LFPH31M6LM&langI
d=-1&storeId=10151&productId=3240526&catalogId=10051&cmRelshp=sim&rel=nofoll
ow&cId=PDIO1

2) 150 - 200 watt solar panel: $280 - $400

http://www.ecobusinesslinks.com/solar_panels.htm

3) Solar charge controller: $32

http://www.adventurerv.net/norcold-compact-gaselect-refrig-way-left-opening-
p-1225.html

4) Cost of inverter $25

http://www.harborfreight.com/automotive-motorcycle/power-inverters/200-watt-
continuous-power-inverter-66967.html

5) Cost of deep cycle battery: $100 (guesstimate)

6) Cost of 2-way fridge from Adventurer RV: $797

http://www.adventurerv.net/norcold-compact-gaselect-refrig-way-left-opening-
p-1225.html

Math:

Lowes Fridge: $219
Solar Panel: $280 - 400
Charge Controller: $32
Inverter: $25
Battery: $100
Total: $656 - $776

Norold 2-Way fridge: $797

http://www.adventurerv.net/norcold-compact-gaselect-refrig-way-left-opening-
p-1225.html

Savings: $141 - $21

I did the same study for fridges here but didn't use it because it the
prices are outrageous compared to the USA.

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426


-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of dave silva
Sent: Thursday, January 27, 2011 1:49 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] solar powered fridge?



OK, one more time....

I am talking about a conventional apartment size reefer from Lowes for $200.


Powered by an inverter connected to a battery and replenished by a 150 watt
solar panel.

If the solar panel can replenish the battery after a long hot night then
this system would be an alternative to spending a $1000 on a two-way Dometic
or Norcold.

The solar panel and the inverter would bring the cost up to the same $1000
or so but if it worked then i think it would be better.

The conventional fridge is a lot lighter, and cheap to replace.

If you don't need Air conditioning then you could dry camp for a long time
with very little energy use.

If you do need AC then the load from the fridge doesn't really matter.
--
Dave & Ellen Silva


Happy owners of a 1972 Flatnose Revcon
Here by the generosity of the GMC community
http://www.davesilva.com/revcon


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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426
Re: [GMCnet] solar powered fridge? [message #113206 is a reply to message #113202] Wed, 26 January 2011 17:31 Go to previous messageGo to next message
k2gkk is currently offline  k2gkk   United States
Messages: 4452
Registered: November 2009
Karma: -8
Senior Member

Rob, please do the tinyurl bit on these long
URLs as they wrap due to your email program.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ex-Palm Beach, 76 ~ ~ ~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~



----------------------------------------
> From: robmueller@iinet.net.au
> To: gmclist@temp.gmcnet.org
> Date: Thu, 27 Jan 2011 09:56:47 +1100
> Subject: Re: [GMCnet] solar powered fridge?
>
> Dave,
>
> Your question got me to thinking so I did some checking and so did some
> checking and found this:
>
> 1) Lowes fridge: $219
>
> http://www.lowes.com/ProductDisplay?partNumber=326297-47224-LFPH31M6LM&langI
> d=-1&storeId=10151&productId=3240526&catalogId=10051&cmRelshp=sim&rel=nofoll
> ow&cId=PDIO1
>
> 2) 150 - 200 watt solar panel: $280 - $400
>
> http://www.ecobusinesslinks.com/solar_panels.htm
>
> 3) Solar charge controller: $32
>
> http://www.adventurerv.net/norcold-compact-gaselect-refrig-way-left-opening-
> p-1225.html
>
> 4) Cost of inverter $25
>
> http://www.harborfreight.com/automotive-motorcycle/power-inverters/200-watt-
> continuous-power-inverter-66967.html
>
> 5) Cost of deep cycle battery: $100 (guesstimate)
>
> 6) Cost of 2-way fridge from Adventurer RV: $797
>
> http://www.adventurerv.net/norcold-compact-gaselect-refrig-way-left-opening-
> p-1225.html
>
> Math:
>
> Lowes Fridge: $219
> Solar Panel: $280 - 400
> Charge Controller: $32
> Inverter: $25
> Battery: $100
> Total: $656 - $776
>
> Norold 2-Way fridge: $797
>
> http://www.adventurerv.net/norcold-compact-gaselect-refrig-way-left-opening-
> p-1225.html
>
> Savings: $141 - $21
>
> I did the same study for fridges here but didn't use it because it the
> prices are outrageous compared to the USA.
>
> Regards,
> Rob M.
> USAussie - Downunder
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
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Re: [GMCnet] solar powered fridge? [message #113229 is a reply to message #113206] Wed, 26 January 2011 21:38 Go to previous messageGo to next message
Don A is currently offline  Don A   United States
Messages: 895
Registered: October 2008
Location: Dallas, TX
Karma: 0
Senior Member

Mac just copy and paste the full link!


Don Adams Dallas, TX
'76 26' Glenbrook, '90 Sidekick
rebuilt by R Archer, powered by J Bounds, Koba
[IMG]http://www.gmcmhphotos.com/photos/data/6109/G2.jpg[/IMG]
Re: [GMCnet] solar powered fridge? [message #113256 is a reply to message #113202] Thu, 27 January 2011 06:06 Go to previous messageGo to next message
hertfordnc is currently offline  hertfordnc   United States
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
Senior Member
Robert Mueller wrote on Wed, 26 January 2011 16:56

Math:

Lowes Fridge: $219
Solar Panel: $280 - 400
Charge Controller: $32
Inverter: $25
Battery: $100
Total: $656 - $776

Norold 2-Way fridge: $797





Rob,

So you're validating my premise? The math may not work all by itself but if one already had an investment in solar, and had to replace a fridge, then it seems to me that adding more solar and switching to a home fridge would make sense.

thanks


Dave & Ellen Silva Hertford, NC 76 Birchaven, 1-ton and other stuff Currently planning the Great american Road Trip Summer 2021 It's gonna take a lot of Adderall to get this thing right.
Re: [GMCnet] solar powered fridge? [message #113264 is a reply to message #113256] Thu, 27 January 2011 07:44 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
Senior Member
Dave,

Not really, I was just trying to see how much one would save.

I did not express an opinion either way.

Like I said I ran the same study here in Australia and the costs are much
higher for both the RV fridge and the Solar Setup.

Having said that Mark Bennett has his coach setup with solar panels and I
believe it is all electric too.

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426


-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of dave silva
Sent: Thursday, January 27, 2011 11:06 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] solar powered fridge?

Robert Mueller wrote on Wed, 26 January 2011 16:56
> Math:
>
> Lowes Fridge: $219
> Solar Panel: $280 - 400
> Charge Controller: $32
> Inverter: $25
> Battery: $100
> Total: $656 - $776
>
> Norold 2-Way fridge: $797

Rob,

So you're validating my premise? The math may not work all by itself but if
one already had an investment in solar, and had to replace a fridge, then it
seems to me that adding more solar and switching to a home fridge would make
sense.

thanks
--
Dave & Ellen Silva

_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist



Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426
Re: solar powered fridge? [message #113268 is a reply to message #113134] Thu, 27 January 2011 08:08 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
hertfordnc wrote on Wed, 26 January 2011 05:44

The Revcon fridge works fine but I'm working on my little scotty trailer and i had an idea that needs testing.

How much solar would it take to sustain a regular 10 cubic foot house fridge?

I'm thinking 200 watts, charging a battery, through an inverter?

Then maybe you hack the fridge's thermostat with a relay so the inverter is cut off between cycles?

It seems to me if you had to replace a two-way Norcold for $1000 you could do just as well putting that money into a system like this.

Is my math wrong? If the fridge draws 1-2 amps and is only on 25% of the time, then a deep-cycle could run it for a while. Would 150 watts of solar be enough to maintain the battery?


Dave,

This is a subject about which I can provide real world data.

We are very capital limited and when the coach reefer went down, I was looking for some solution that did not involve scraping the coach.

We bought a little Frigidarie that would fit in the space at one of the big box stores. A 50$ 750 watt inverter from HF (on sale for 30$), and a plug and a box and some wire (~20$) again at LowDespot (they are close). My coach now has a pair of GC2 for a house bank (225Ah). During the next excursion, a Friday evening drive to Sunday evening backhaul, we did run the APU for a half hour for the microwave and hot water Saturday evening, but the coach house bank did not show signs of being over taxed.

You need a big inverter with short, heavy wires to a large size battery to support the starting load of the crumby Chinese compressor. The actual running load is less than 100 watts, but the starting load is an issue. If you buy an HF inverter get their replacement plan and they are know to have issues.

There is another problem with the little reefers. The condenser is the shell. So, it will not work well in a tight space. It needs space on both sides to cool effectively.

You can shed a lot of light on the whole problem with a spreadsheet. Both for power budget and cost budget, but it largely comes out to what you already have or can use. I use some of the inverter capacity to charge things for which I do not have 12VDC charger.

Where I put the inverter, it is not very accessible, so I did carefully hack into it to provide a remote switch (save the parts in case the smoke leaks out and you have to take it back).

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: [GMCnet] solar powered fridge? [message #113285 is a reply to message #113264] Thu, 27 January 2011 10:08 Go to previous messageGo to next message
comcast is currently offline  comcast   United States
Messages: 604
Registered: August 2009
Karma: 0
Senior Member
> Math:
>
> Lowes Fridge: $219
> Solar Panel: $280 - 400
> Charge Controller: $32
> Inverter: $25
> Battery: $100
> Total: $656 - $776
>
Norold 2-Way fridge: $797

OR:

Fridge: $219
Inverter: $25
Battery: 2 additional 6vdc $200
Combiner: $100
Total: $544

Even less if you already have a combiner.
Batteries can be placed behind the fridge for access through vent door.
You can then add solar later if needed or charge via engine or
generator when/if needed.

Roger Black
77 Birchaven
Burns, Tn




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Re: [GMCnet] solar powered fridge? [message #113290 is a reply to message #113285] Thu, 27 January 2011 10:39 Go to previous messageGo to previous message
jknezek is currently offline  jknezek   United States
Messages: 1057
Registered: December 2007
Karma: 5
Senior Member
Quote:


Fridge: $219
Inverter: $25
Battery: 2 additional 6vdc $200
Combiner: $100
Total: $544

Even less if you already have a combiner.
Batteries can be placed behind the fridge for access through vent door.
You can then add solar later if needed or charge via engine or
generator when/if needed.

Roger Black
77 Birchaven
Burns, Tn




This is the route I think I'm taking. Our fridge is starting to go. Doesn't work on 12 volt and doesn't work well on the landline either. We already have a combiner, but I'll have to check if it can work with 3 battery banks. Either that or I'll run new wiring from the inverter in the electric cabinet over the top to where the fridge is located.


Thanks,
Jeremy Knezek
1976 Glenbrook
Birmingham, AL
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