Do you really need to spend 8K dollars to run a 600Watt fridge?

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

I don't know about the claims, but when they list a BZ240 charge controller as one of their components, I walk away. Cheap crap.

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

ericlp wrote: »

http://partsonsale.com/sundanzer.html

I don't know about you but if I had to spend 8K just to run a refrigerator it's be hooking my house up to the mains and would never think about going off grid.

Now that we've kicked around the accuracy of the estimate of 8k to run a refrigerator, lets look at the other part of you comment.

If you want cheap reliable power, in many parts of the world the power grid is the place to get it. The mitigating factors are:

• Some places have incentives (tax, power buybacks, etc.) that make solar power more reasonable
• Some places do not have access to a reliable power grid
• Some people are willing to spend money to be less reliant on the power grid
• Some people like the technical challenges

In any case, conserving power is cheaper than generating it.

If your real question is, "Don't you have to be nuts to do solar instead of the power grid?", the answer is "No, but it helps."

Keith

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

I think the OP is missing a critical part of the equation. That is, why would one wish to go off the grid if one has grid power available? Grid tie PV solar comes at about 1/2 the cost per installed watt, with about twice the efficiency, leaving a system that is ~ 4 times more bang for the buck.

An 8000 system might buy about 1.5 kw of grid tie PV, which might yield ~ 4 kwh/day perhaps, on average. (Run and grid tie PV Watts Calc)

The point here, is any battery based Pv system is by it's very nature, very expensive to buy and maintain, ergo the kwh cost of the power is also very expensive! If you goal is to save money, do conservation. If your goal is to be "green" go grid tie. If your goal is to play around and learn about PV, build a small battery based system to see what you can do with it.

Tony

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

Doesn't this sort of beg the question,, if you are desiring a back up system to the grid, isn't ~$6000 to power the freezer a bit steep? The same $6k in gird tie, might put out ~1200 watts day in and day out. That plus a Honda Eu generator for the outage times might make better sense. Just a thought. (your fire shelter issues not withstanding, as it sounds like you are in a fairly unique situation)

Tony

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

oops:D I started this post a while back and did not see BB's note before posting: (edit)

if you are desiring a back up system to the grid, isn't ~$6000 to power the freezer a bit steep?

Agreed, however it is $4500 after the credit but even that is steep if all you want is to power a freezer.

In my case I need an instant fail safe system. Wildfire is a real threat. I don't trust a small engine generator to work when I need it.

There are other ways. I could set up a UPS system with just batteries, an inverter a charger and a better generator for guessing about $3000. However there would be no tax credit.

$4500 for a solar charged UPS system compared to $3000 for a grid charged UPS system. (not exactly UPS as there is no automatic switching)

The freezer draws about 1000 watt hours per day and the block heater, water pump, inverter add another 1000 watt hours per day. At 30 cents a killowatt hour that is $2190 over ten years assuming no increase in the cost of electricity.

Now the comparison is $4500 initial solar cost minus $2190 electric savings = $2310 compared to $3000 for a grid charged UPS.

The same $6k in gird tie, might put out ~1200 watts day in and day out. That plus a Honda Eu generator for the outage times might make better sense.

Grid tie doesn't do anything in an emergency when the grid is down. I only started looking at alternatives to the grid after the utility informed me that they would be shutting down the grid in a fire emergency. I would rely on a small engine generator for back up but not for emergency backup. I considered a 7kw Kuboto diesel generator for $5000.

Considering tax credits and electricity savings $2500 for solar emergency backup doesn't seem unreasonable to me and it is a lot more fun than the alternatives.

Zeuspaul

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

Ericlp,

Slow down a bit. You are running the risk of the greatest pitfall in RE, that is the "Ready, Fire, Aim!" syndrome.

Before you buy, or build anything, sit down, and do real, and real time load calculations factoring in all your likely uses. Build in some fudge factor for loads that will inevitably grow with time. Once you have your load calcs, you can then begin to size components, working backwards from Invereters, to batteries, to charge controllers to PV.

Just for the record, an off grid Pv system net numbers might look something like this. Take the name plate rating of the PV, divide that number in 1/2 to account for all system loses (PV/wiring/charge controller/battery chemistry/inverter etc) then take that number and multiply it by 4. That represents the AVERAGE number of hours of good sun one can expect on a 12 month basis. Some areas might get a few more, but not too many on an annual basis. For example, you might have ~12 hours of daylight in Hawaii on average, but how much haze is in the air early or late, how many hours of puffy cloud, how much over cast etc?

So your proposed 1,250 watt system might look like this

1250/2=625*4=2500 wh/day, or 2.5 kwh/day. There will certainly be days when you might get more, but there will most certainly be days when you get less. One often overlooked efficiency number with off grid PV systems is the amount of power that is lost (not generated) when the batteries come close to full and the charge controller drops currents back. This is one reason I like to use the 50%*4 rule more than a more conventional PV watts that gives a more best case, but not real situation for off grid.

So knowing that you can reliably generate ~2.5 kwh/day gives you a starting point in knowing if that will fit your loads.

want a full size fridge with an ice maker no more the 400kWh per year. Run a TV, Computer, Washer Machine, 12v water pump. Ceiling Fan, Lights (led), Satellite Receiver, modem, skill saw, battery chargers for rechargeable drill, Alarm Clock, charger for cell phone, a blender ... Maybe a microwave tho I can probably do with out one.

Don't need AC, Water Heater will be Passive solar, and any cooking devices will be run off propane like BBQ, burner for making tea / coffee and or cooking.

I have a pretty good hunch that you are going to have way more loads than capacity. A couple of guestimates:

Fridge .5kwh/day, computer .3 kwh, pump .1, ceiling fan 35 watts 24/7= .8 Sat receiver 4 hours .2 kwh, TV 4 hours= .4 for a total of just that stuff ~2.3 kwh charge the drills, charge the phone and you will be way over. It is very common for people to over estimate the amount of solar power they can harvest, at the same time underestimating the loads they actually use.

Just for the record, we have ~400 watts of PV, we routinely use ~.6-.8 kwh/day. We can go three days without using a generator. On a really good day we can generate ~ 1.5 kwhs (more in the summer) but I use the 50%*4 rule for the whole year and it works out just fine.

Good luck,

Tony

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

Sure its possible to use a chest freezer as a fridge but its such a pain to do so.. Itried it soon gave up and it drove my wife mad. its hard to lean into it to get things out"she is only 5'4" .THre seems no simple way to put things on top of the things at the bottom then easily get the things out from underneath. It nearly impossible to use all the interior space the simple way you can with a refrigerator.

It not that expensive to run a refrigerator off solar and batteries or that difficult..
Well its not with refrigerators made up to about 2 years ago but I have been told the new ones work "differently" to the older ones,, but dont know what the differences are as im not a fridge mechanic

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

EriclpIm a bit confused about this. can you explain??Another thing you do realize what .1kwh is don't you? You can't get a fridge this size a normal stand up one to go below 400kWh

Uh, 36 vs 400kWh.

I had and still have Whirlpool chest feeezer 20cft and and a 16cft Whirlpool fridge
The chest freezer uses about 960 kwh per year the fridge uses about 450kwh per year.


Freezers have thicker walls with more insulation R value then a standard fridge

This is not true for my fridge and freezer in fact the fridge wall thickness is slightly more than the chest freezers

So, can you share what freezer you had and how you wired it up and what kinda readings were you getting from it?It is just a standard chest freezer? only reading was 960kwh per year

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

80% is a pretty good bench mark figure. I would bet in Hawaii you are going to get less on average.

As for chest freezers to use as fridges. While they are very efficient, they are a pain to use, as in order to use the volume, you have to stack stuff on top of other stuff, the net result is you have to always be taking stuff out to get to other stuff, negating some of the advantage.

I'm sure there are those that have felt that headache worth it,,, but not me!

Tony.

Edit: sorry, didn't realize most of this had already been said,

T

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

maybe you need a frig lazy susan.;)

Re: Do you really need to spend 8K dollars to run a 600Watt fridge?

So your 20cft freezer becomes a 10cft fridge,, just great.. I really think unless you willing to put up with huge inconvienence using a chest freezer as a fridge is not practical . Nobody can ever show how to make full or even 3/4 of the freezer usable. And by usable I mean make any item easy to get in or out for all members of a family, mum ,dad and the kids big and small.:cool:

Something else never mentioned if you now use a chest freezer as a fridge instead of your "old fridge" where do you keep your items you need to keep frozen??? in the frezer half of the "old fridge" ?? or in another chest freezer???Seems self defeating to me