Will this do the job on a sunny day?

Have looked through the forums and found some info which is a bit old so thought I would throw this out there and see what you think.

The plan - 10 year old Waeco CF110 fridge + 100 watt solar panel with regulator + 115AH Deep Cycle battery.

The fridge specs say it draws around 3.5 but I read elsewhere on the forum it is more like 4-4.5.

We are in Central Queensland and thought we could count on at least 8 hours sunlight per day (8am-4pm).

Would appreciate feedback from anyone who has the CF110 and similar setup or anyone who has anything interesting to say!
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Reply By: Rangiephil - Tuesday, Sep 18, 2012 at 14:13

Tuesday, Sep 18, 2012 at 14:13
IMHO you will be a bit marginal.
It will depend on the duty cycle of the fridge and how many amps it actually draws. If it is 4.5 amps with the fridge running, if the duty cycle is 50% then you will use 2.25X24 = 54amp hours per day.
a 100 watt panel will not give 100watts through a PWM regulator, but an MPPT will give more.
However , say you get 5amps for 4 hours ( my 120watt gives 6amps at 1PM)and 2 amps average for 3 hours, that is 26 amp hours total per day generated.

Your battery will give about 50% of its capacity without damage so it will give 60amp hours roughly.

So the fridge should run about 2 days at 50% duty cycle before the battery is effectively flat. That assumes 50% duty cycle and in hot weather this is not certain or even likely.

That is a big fridge so needs a lot of power.
Regards Philip A
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Follow Up By: Cathy M - Tuesday, Sep 18, 2012 at 16:17

Tuesday, Sep 18, 2012 at 16:17
Thanks for the analysis Rangiephil - very helpful.
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Reply By: Member - Sn00py2 (NSW) - Tuesday, Sep 18, 2012 at 14:14

Tuesday, Sep 18, 2012 at 14:14
Hi Cathy,

The above configuration will not be enough to power your fridge. If the fridge draws an average of 4.5amps/hour then it will draw up to 108 Amps in 24 hours (4.5amps *24hours = 108Amps). Your solar panels will produce 100watts/hour which is 8.33Amps/hour. In 8 hours it will produce a total of 66.67Amps so you will be short 41.33Amps/day which will be drawn from the battery. Your 115Amp battery, which should only be discharged to 50% (57.5Amps) to get a decent life, will therefore only provide this shortfall for just over a day.

For your set up you need at least 200Watts of solar panels to stand a chance of it being sufficient. Remember, not all days are sunny and cloud cover will reduce your ability to produce power. Also, you may be able to lower the load the fridge draws by keeping it out of the heat (shade, good ventilation and insulated cover) to get by.
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Follow Up By: Cathy M - Tuesday, Sep 18, 2012 at 16:29

Tuesday, Sep 18, 2012 at 16:29
Sn00py2 I am hoping that the 4.5 amps that I read on a thread is over the top for the Waeco. One thing you did not consider is that the compressor won't be running for 24 hours. At night the fridge will not be opened for at least 7 hours plus it is cooler at night, so I am working on the compressor running 15 hours = 67.5 amps. If it draws less than 4.5 then it will be even better.

Have been thinking of the cloudy days and might have to use a generator or rig up a dual battery system with the vehicle. Whatever we do there's no doubt it will cost more $!
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Reply By: pop2jocem - Tuesday, Sep 18, 2012 at 15:43

Tuesday, Sep 18, 2012 at 15:43

Not sure if this suggestion is useful or practical in your situation.
I don't have a solar setup but am currently (if you'll excuse the pun) working on one. What we do is let the fridge run for about an hour after the last food or drink is taken out, usually at night, and then either shut it off or at least turn it right down depending on the ambient temperature and turn it back on the next morning. It seems to help conserve the battery a bit and depends on when the car is next started.

AnswerID: 495166

Follow Up By: Cathy M - Tuesday, Sep 18, 2012 at 21:55

Tuesday, Sep 18, 2012 at 21:55
Thanks pop2jocem - sounds like an option but was thinking that we would need to be topping up the fridge with beer/wine/water for the next day so would need to take into consideration the load that would put on the fridge ie better at night or at midday when there is full sun? I have read fridges work better full (a waste of energy cooling air which escapes every time you open the fridge) which led me to and article about a guy who made small beanbags out of shade cloth. He would just throw the beanbags in the fridge as he took stuff out. The beanbags (full of polystrene balls) would mould to fit the space and wouldn't absorb any energy - pretty clever bloke I thought - might have to get out the needle and thread!
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Follow Up By: Member - silvwayne - Wednesday, Sep 19, 2012 at 06:15

Wednesday, Sep 19, 2012 at 06:15
Make sure you put your beer and wine in in the morning when it is cooler than at night.

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Follow Up By: Cathy M - Wednesday, Sep 19, 2012 at 09:01

Wednesday, Sep 19, 2012 at 09:01
Thanks Wayne - that makes sense!
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Reply By: Bob Y. - Qld - Tuesday, Sep 18, 2012 at 20:49

Tuesday, Sep 18, 2012 at 20:49

Can't help you with any info on the Waeco, but can offer some advice on your solar panel.

Unless you are prepared to "track" the sun with your panel, you won't get 8 hours of peak sun. Would suggest peak hours with a stationery panel would be more like 4 hrs. We've got panels on the shed, and it is at least 10am before approaching peak watts, and then by 2 or 3pm, it's already falling towards 50% output. Was amazed, and disappointed, at the effect the different angles of the sun, affect the output. An MPPT regulator would boost things along a bit better for you.

We are in Central Qld too, so get plenty of sunshine. Also, a number of people on this site have bought panels from Bit Deals. They're panels are pretty good value, and the service has been good too. No affiliation etc.

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Follow Up By: Cathy M - Tuesday, Sep 18, 2012 at 22:05

Tuesday, Sep 18, 2012 at 22:05
Well that's disappointing Bob Y. Of course we can move the panels to face the sun but who wants to be tied to the campsite to do that tedious job?! Have taken on board the MMPT which RangiePhil mentioned earlier and have done some investigation. It looks like a good option to make the most out of the panel. So much involved in creating power without the option of connecting 240V - makes the cost of electricity to our homes seem cheap in comparison not to mention convenience.
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Follow Up By: Bob Y. - Qld - Wednesday, Sep 19, 2012 at 10:29

Wednesday, Sep 19, 2012 at 10:29
Sorry for being a party pooper, Cathy. But I wasn't happy about their performance either.

Am sure with the hints given by the others you will achieve some success. Pop's suggestion about turning the fridge off, is what we've done when we had limited battery capacity(no 2nd battery), and it worked well in mild weather.

Don't forget that you could, depending where you are camped, run the vehicle for an hour in the morning, or evening.. This will give the battery a significant hit, before the solar kicks in later in the day.

Have to agree, town or rural power is quite cheap, when you consider the alternative, generating your own power. Now that's a quick way to spend a lot of money!!! Speaking from experience here.

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Follow Up By: Cathy M - Wednesday, Sep 19, 2012 at 11:03

Wednesday, Sep 19, 2012 at 11:03
Thanks Bob.....pretty much leaning towards the generator as back up at this point and charge up in the morning before the solar kicks in as you say and just after we put in the beer/wine!!
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Reply By: Cravenhaven - Wednesday, Sep 19, 2012 at 07:56

Wednesday, Sep 19, 2012 at 07:56
We have a new model Waeco CF80 which I believe uses the same compressor as the CF110. When I bought the fridge I ran a number of tests to find out just how much power the fridge would use (to compare to the 2 older fridges that we had previously used). I found that the fridge draws approx 4.5 amps when running (starts at 6 amps and drops to 4.5 for most of the on-time) and ran at about a 50% duty cycle with an ambient temperature of 18 degrees and configured as one cabinet, ie dividers removed and keeping a couple of bags of ice frozen.

In practical use we have approx 250AH of battery and can run without external power for 2-3 days in Queensland in the winter months when using the fridge as a combined fridge/freezer.

We also have an 80watt panel which I drag out if we are confining ourselves to the campground for a longer period and get a peak output of 5 amps when it is cool, but in normal use it will provide closer to 4-4.5 amps provided I keep it aimed at the sun. In summer the output drops to 3.5-4 amps. We get around 25 AH per day from the panel in winter like this.

In your case your CF110 fridge will draw more power than our CF80 and you have less battery and are not planning on being 'tied' to your campsite to move the 100W panel around. You need a much bigger solar setup, or a generator to satisfy your requirements.

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Follow Up By: Cathy M - Wednesday, Sep 19, 2012 at 09:10

Wednesday, Sep 19, 2012 at 09:10
Thanks Cravenhaven.....have been thinking a generator as a back up would be useful in more ways than one. I have done a bit more research about the way solar panels work and was surprised that they are more effective in cooler conditions as you point out. Appreciate your feedback.
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