PV Backup

[Brian Graham]

I've certainly heard about propane fridges. What about freezers?

I've crunched some numbers and my freezer (2kw/day) will take (6) 150 Watt panels (+ 2 more for recharge capability) and a good battery bank (I forget the numbers offhand) for 4 day backup. Its going to cost a LOT to run this puppy PV.

Of course, my family room with TV/Stereo/Computers on all day will be FAR more than that if I were to go totally PV.. :-(

Hence the bottom line is a HUGE startup expense, even for something "simple" as a PV backup for fridge/freezer for when the power is off.

Or am I missing something obvious?
—
Brian

 

[Steve Spence]

a sears Kenmore 8.8 cu. ft. chest freezer ($220) is rated for 300 kWh /
year, or approximately 820 wh / day. Three 100 watt panels should do nicely,
depending on climate.


A frostek propane freezer ($2200), with 8.5 cu. ft. capacity consumes 1.8 -
2.5 gallons of propane a week.

That $2000 difference would buy the panels and them some, with no propane
bill.

Maybe it's time for a new freezer?

--
Steve Spence
Renewable energy and sustainable living
http://www.green-trust.org
Discuss vegetable oil and biodiesel
powered diesels at
http://www.veggievan.org/discuss/

I've certainly heard about propane fridges. What about freezers?

I've crunched some numbers and my freezer (2kw/day) will take (6) 150 Watt

panels (+ 2 more for recharge capability) and a good battery bank (I forget
the numbers offhand) for 4 day backup. Its going to cost a LOT to run this
puppy PV.

Of course, my family room with TV/Stereo/Computers on all day will be FAR

more than that if I were to go totally PV.. :-(

Hence the bottom line is a HUGE startup expense, even for something

"simple" as a PV backup for fridge/freezer for when the power is off.

 

[Dave]

DC Fridges using the Danfoss compressor use about half the power of a
conventional AC fridge- even in tropical climates- see FAQ at
www.rpc.com.au

Dave

 

[Melodie de l'Epine]

If it's just to get you throught 10 hours or so of electric down-time,
don't bother - all "good" freezers have that much safety margin. Just
don't open the freezer, and everything should be fine.

If you're looking for 4 days backup - maybe you should check out your
insurance, most insurers can cover you for money lost when a long outage
means a lot of spoilt food. (or food you had to eat earlier than
expected). that way you can restock after the outage. Probably costs a
lot less, and if you make sure the food gets used (cook it then
refreeze, donate, have a party and eat everything...) it's not really
wasteful.


Mel


Brian Graham a écrit :

 

[Pom-pom-pom]

If it's just to get you throught 10 hours or so of electric down-time,
don't bother - all "good" freezers have that much safety margin. Just
don't open the freezer, and everything should be fine.

If you're looking for 4 days backup - maybe you should check out your
insurance, most insurers can cover you for money lost when a long outage
means a lot of spoilt food. (or food you had to eat earlier than
expected). that way you can restock after the outage. Probably costs a
lot less, and if you make sure the food gets used (cook it then
refreeze, donate, have a party and eat everything...) it's not really
wasteful.


Mel

LOL, good incentive for parties!

Thanks to our beloved utility*, John Doe is pleased to invite you for his
25th Black-Out party!
All you can eat molten ice cream
Bring your own flashlight


*Or Trade Union, depending on local culture.

 

[Brian Graham]

If all you want is backup power for a few hours when the power goes out,
then reduce the amount of solar panels and add more batteries. Depending on your specifics, you could go with as few as 2 of the solar panels. Add more batteries to compensate. When the power comes back online, the system will start trickle-charging the batteries and will be available in case of
another outage within a week or so. <<<

You can likely tell from my original posting that my desire is not just backup but ultimately off-grid. Hence my reference to my family room. But you made a good point regarding backup capability. And I'd start by being able to have backup power available and adding slowly from there.

Ottawa, Canada. My spreadsheet is at home so I'll see what I can recall offhand.

2000 watts/day for my chest freezer. From a 12V system= 167.7 ah + 15% for inverter inefficiency = 192 ah daily.

10amp panels, 4 hrs per day = 40ah per panel.

192ah / 40ah = 4.8 panels = 5 panels required. + 2 for recharging bats once used = 7 panels. Hmm. Think I was using 8amp panels in my spreadsheet.
SunFrost freezers. They use a fraction of the energy of a typical freezer,
meaning a cheaper solar system to run it when the power goes off, and a
lower utility bill when the power goes back on. <<<

It might be an idea. But in terms of running my electronics off-grid, its clearly going to require a LOT of panels, &/or a change in lifestyle. No more running the TV/VCR/Stereo/Computers 16 waking hours a day. That would be a LOT more than the freezer!

 

[Chuck Yerkes]

I've certainly heard about propane fridges. What about freezers?

I've crunched some numbers and my freezer (2kw/day) will take (6) 150 Watt panels (+ 2 more for recharge capability) and a good battery bank (I forget the numbers offhand) for 4 day backup. Its going to cost a LOT to run this puppy PV.

Of course, my family room with TV/Stereo/Computers on all day will be FAR more than that if I were to go totally PV.. :-(

Hence the bottom line is a HUGE startup expense, even for something "simple" as a PV backup for fridge/freezer for when the power is off.

Well a "simple" backup for the biggest energy user in your house.

Or am I missing something obvious?

When the north east lost power for 5 days, as is usually the case, it
was in the winter. A lot of mom's freezer contents went in the basement
between the insulated door and the hatch to the outside in coolers
(unsealed). Animal proof and cold.

The ice cream was deemed unable to survive that and consumed.

So if you're using it as an "oh crap, I've got not power" in that
extremely rare situation, then a generator will be less costly to start
and, since it's not in use daily or weekly, the noise/smell/enviro-cost
can be rationalized away.

And do your calculations cover that batteries get recharged in the day?
Reasonably, you'd only need an 18 hr backup.

If it's winter, with less canadian sun, then...well, it's COLD OUTSIDE!
Take advantage.


As far as "going off grid" - if you're not moving, why?
There's another term: "Not using any grid power" that can be had.
Especially with Net metering.

I'll be delighted to be a net-zero customer.

(I'd be overjoyed if they would pay me for over generation, I'd put up
another 10 panels and make some money from it. Hell, even credit
against the gas bill would be dandy.)

Going off grid without lifestyle changes from a consumptive lifestyle
would mean that you're paying a LOT up front for that lifestyle.
It just makes choices clear.
$500 35" CRT TV or a $600 20" LCD TV that uses 1/4 the power. Or
no TV.

One never-bad thing to try is putting away your TV for a month. The
first week is hard, then you learn to get games and books of games and
read more. Or interact. 30 days of no TV would hardly harm anyone
long term and you can rationalize it to kids in the summer with the
rerun factor.

chuck

 

[Steve Spence]

you are only 1.5 hours north of me (Potsdam NY). We are offgrid. Give me a
call sometime.


--
Steve Spence
Renewable energy and sustainable living
http://www.green-trust.org
Discuss vegetable oil and biodiesel
powered diesels at
http://www.veggievan.org/discuss/

out,
then reduce the amount of solar panels and add more batteries. Depending

on your specifics, you could go with as few as 2 of the solar panels. Add
more batteries to compensate. When the power comes back online, the system
will start trickle-charging the batteries and will be available in case of

another outage within a week or so. <<<

You can likely tell from my original posting that my desire is not just

backup but ultimately off-grid. Hence my reference to my family room. But
you made a good point regarding backup capability. And I'd start by being
able to have backup power available and adding slowly from there.only about 2 hours of peak sun per day to require 6 pv panels. You may be
cutting yourself short on this figure. <<<

Ottawa, Canada. My spreadsheet is at home so I'll see what I can recall offhand.

2000 watts/day for my chest freezer. From a 12V system= 167.7 ah + 15% for

inverter inefficiency = 192 ah daily.

10amp panels, 4 hrs per day = 40ah per panel.

192ah / 40ah = 4.8 panels = 5 panels required. + 2 for recharging bats

once used = 7 panels. Hmm. Think I was using 8amp panels in my spreadsheet.

SunFrost freezers. They use a fraction of the energy of a typical freezer,
meaning a cheaper solar system to run it when the power goes off, and a
lower utility bill when the power goes back on. <<<

It might be an idea. But in terms of running my electronics off-grid, its

clearly going to require a LOT of panels, &/or a change in lifestyle. No
more running the TV/VCR/Stereo/Computers 16 waking hours a day. That would
be a LOT more than the freezer!

 

[Steve Spence]

and go to propane freezer/fridge.

--
Steve Spence
Renewable energy and sustainable living
http://www.green-trust.org
Discuss vegetable oil and biodiesel
powered diesels at
http://www.veggievan.org/discuss/

"Brian Graham" <[email protected]> wrote in message

its clearly going to require a LOT of panels, &/or a change in lifestyle. No
more running the TV/VCR/Stereo/Computers 16 waking hours a day. That would
be a LOT more than the freezer!

 

[Steve Spence]

Between my propane fridge, stove, hot water heater, and my dryer, I'm using
75 gallons a month, at $1.44 / gallon ......

I'm working on my anaerobic methane biodigester .....

 

[Brian Graham]

If you check over at alt.solar.thermal, you'll see I have something similar in mind. (Thread Will this Work?...) And the answer seems to be a very big YES!
I've got three large passive solar hot water panels coming (~3'x8'),
the vacuum tube type, that I'm hoping will put a nice dent in my
heating bill next winter!