need to boost my solar capability

[Fhunter1]

Looking for some sage advice on solar charging units / size,

I basically use very little 12V power aside from fridge Norcold 45 and charging an occasional phone or HT ham radio. Usually I charge phones or the HT on the Jeep when we run an errand or when out adventuring.

I has a SolarFilm 60w panel which just can't seem to keep up with the Fridge. After about 3 days I am down to about 11.5 or 11.3 volts in the battery. On a long stay somewhere I have been using the jeep to charge it back up to normal level of 12.7 +.

So around Christmas I decide I needed to fix the situation so we were good to go when the weather breaks a bit. I thought perhaps the fridge was just older and pulling too much juice so I start to research options for replacing the fridge and started to look at the power consumption and the recommended solar panel sizes to run them.

My general assumption is that I should be running about a 100 W panel instead of the 60 W. Is that assumption correct?

Assuming it is what is my best option. ? I like the PowerFlim and a 120W panel is fairly pricey. I could daisy chain another panel (30W) and then be at 90W. Is 90W enough to support a fridge out west(Arizona Utah, Texas, etc) in the summer? Is there another option I should consider?


Thanks in advance

 

[AndrewP]

60 watts should be close to enough to support just routine fridge use. Do you know the actual output from your panel? Just because it says 60 watts doesn't mean that's what you're getting.

I would measure the output with a watt meter (Amazon, $20). You should be getting about 3 amps in good sun.

Just an aside-One of my friends had his very expensive Powerfilm 60 watt panel fail. It would start to work, and charge, but as soon as it warmed up, it would stop producing power. They had a known issue in the panel electronics and fixed his no questions asked. We figured it out by using a wattmeter and would see his output drop from about 3 amps to zero after 5-10 minutes.

Something like this will help a lot and is even cheaper now than a year ago!:
http://www.amazon.com/GT-Power-Anal...F8&qid=1453594982&sr=8-11&keywords=watt+meter

 

[IdaSHO]

Do the math. I bet your 60 watts isnt remotely enough to actually keep up with your fridge.



Average amp-hour consumption x 24 hours

Average hours per day of good sun x amps produces by panel.




FYI, a GOOD 60 watt panel should be producing roughly 5 amps at 12Volts

And GOOD sun, is rough 6-8 ours a day. 5amps x 6 hours = 30 amp hours.



A quick google search yielded the following:

http://www.defender.com/product.jsp?path=-1|2276204|2276226|2276228&id=1629856

States that the average amp consumption for that fridge is 50watts. 50 watts @ 12 volts = 4.16 amps

So, 4.16 Amps (average draw) x 24hours (1-day) = 99 amps



So in a nutshell you are producing roughly 30 amps per day. but your fridge (alone) is consuming 99 amps.


For dry camping, you need more solar, or more battery, or both.

If anyone spots an error in my math, please let me know :snorkel:

 

[fredgoodsell]

Do the math. I bet your 60 watts isnt remotely enough to actually keep up with your fridge.



Average amp-hour consumption x 24 hours

Average hours per day of good sun x amps produces by panel.




FYI, a GOOD 60 watt panel should be producing roughly 5 amps at 12Volts

And GOOD sun, is rough 6-8 ours a day. 5amps x 6 hours = 30 amp hours.



A quick google search yielded the following:

http://www.defender.com/product.jsp?path=-1|2276204|2276226|2276228&id=1629856

States that the average amp consumption for that fridge is 50watts. 50 watts @ 12 volts = 4.16 amps

So, 4.16 Amps (average draw) x 24hours (1-day) = 99 amps



So in a nutshell you are producing roughly 30 amps per day. but your fridge (alone) is consuming 99 amps.


For dry camping, you need more solar, or more battery, or both.

If anyone spots an error in my math, please let me know :snorkel:

Seems like the average well-insulated compressor fridge (depending on ambient temp, and lid opening habits, of course) only runs roughly half of the time, not 24/7. So it would draw about half of your calculations. I think?

 

[IdaSHO]

Average is average is average.

Average power consumption for that fridge is 50Watts.

 

[AndrewP]

IdaSHO-Remember the panel does not operate at 12volts. If it did, the battery would never charge. So in reality, it's going to charge the battery at 14volts, which puts the best case absolutely perfect conditions theoretical best closer to 4 amps. And since the real world has inefficiencies, wiring losses, and less than perfect sun, it's really like 3 amps. On a good day.

I've actually measured fridge use, and I have an Engel 45 and the average daily hot weather power consumption is 20 amp hours, give or take. So a 60 watt panel should get you close. Not quite there, but close. Since just a battery alone can often get you 2 days, a 60 watt supplement *might* under excellent conditions get you to 3 days.

Most 12volt fridges of this type draw around 3-4 amps when running. THe duty cycle is not 100% though, it's more like 30% in the day and less at night. So That's 4amps x 0.3 x 24hours chis is about 30 amp hours. So it's close.

So you asked for your errors to be pointed out, and there they are!

 

[IdaSHO]

No error, just a method to keep things simple.

Of course the 12v system does not operate at 12v all the time.


However when dealing with a 12v system, both solar production and draw calcs are to be based upon 12v, if only to make things simplistic.


The reality is that NO solar panel charges at 14V from the moment it receives a bit of sun.

Nor is it limited to 14V, unless specifically set there. I have mine set up to charge at nearly 15 volts.


So unless you have hard data to prove that a solar setup is producing X Amps per day,
as well as hard data to show your draw is X amps per day, the use of 12V is more than adequate.


So no matter how you butcher the math, the fact is simple, as I have stated already....

For dry camping, you need more solar, or more battery, or both.

 

[calicamper]

Renogy just sent some owners a note that the flexible panels might develop a crack which heats up then causes cell failure. I know a few expo folks have said that their 80watt hard panel easily keeps their fridge and battery topped up nice. 60watt is cutting it close and the flexy panels are a little wonky and may even have an issue further limiting your power generation. Its ok to go multiple smaller panels if storage is an issue. My set up is a micro system no fridge 18ah battery for some lights and a charging hub station I keep it happy with two 10watt panels I just set out in an extra chair.

 

[calicamper]

Check out an 80watt hard panel. Or say two 40's. The storage options might work for you.

 

[calicamper]

This would be a great idea
http://www.amazon.com/gp/aw/d/B00XJ...olar+panel&dpPl=1&dpID=51l1Qj-jWAL&ref=plSrch

100watt would for sure do it. You would have more power than you would know what to do with.

 

[IdaSHO]

Check out an 80watt hard panel. Or say two 40's. The storage options might work for you.

Agreed though at 80watts your still coming up short.

Do realize that my math is for dry camping, regardless of duration.
Current setup I have will keep the fridge running no matter how long Im stopped.


Also, Ill always suggest a traditional panel over a film.

The cells generate enough heat with air flowing under them.
Never would I ever temp a film, that cannot breath at all.

 

[calicamper]

Yes heat dramatically impacts the performance. My other solar project was just finished Thursday. 29 285watt LG panels each with an enphase inverter. All tied to the house and a envoy system hub that will let me view each panel output. Very cool system!!! Just need the final building inspection then power company approval to flip it on. 3yr return on investment, I speced it out with a solar equipment seller not a solar company total install cost was half the price of the solar company quotes we had. For junk gear too.

 

[jonyjoe101]

an edgestar fp430 12 volt fridge consumes about 25 amps in a 24 hour period when set to 40 degrees, I measured with a dc wattmeter. All danfoss compressor fridges use about the same.

A 120 watt panel (21 volt) connected to either pwm or mppt controller will give you bout 6 amps of power when the sun is overhead in clear weather. To me this the minimum you need to keep up with the fridge, as long as you have good sun. Its what I used for months at a time and I was using a small 75 ah agm battery, but larger battery will help in case you have several days of bad weather.

On the roof of my astrovan I now have a 240 watt solar panel (36 volt) connected to an ecoworthy 20 amp mppt, I get about 12 amps of power, more than I need. Once you experience the power of the large panels you wont want to go back to the smaller panels. You can never have too much power.

Rule of thumb from my own experience
You get about 1 amp of power from every 20 watts of panel.
Mppt controllers only increase amp output on high voltage panels about 30 volts or higher.
To find out the max power a panel will produce in the best situation/mppt controller is watts/14.4 volts = amps , example 60 watts divided by 14.4 equals 4.1 amps. 14.4 volts is the minimum voltage needed by most batteries for the best charge. 60 watt panel being low voltage would never benefit from mppt and reach its full potential.

You can connect this dc wattmeter (about 15 dollars) to your fridge to find out how much amps it consumes, it also can be connected to your solar panel to see how much amps you produce every day.

 

[Semi-Hex]

View attachment 326605

It is always worthwhile to test your usage.
The other thing I always see is undersized wiring and runs that are too long.

 

[Fhunter1]

Lots of fantastic information here.

I need to check the output and demand as suggest but I will probably wait until the snow melts here to get a good read on the fridge draw.

In regard to the comments about wiring, are we talking about the solar panel and regulator wiring here? If so what would you reccomend for the minumum guage wiring?

I guess it is time to add a power meter to the system other than just the volt meter to see what is really happening. I also find it interesting to note the comment about heat and the flex panels. I normally use the panel on top of my Conquerer which is dark green. So heat might be an issue.

The 2 occasions when I noticed it on mulit day trips were in the Badlands last fall, Clear sky and full sun most of the day. Temps bounced around a bit but warm during the day (80s and 40s at night). The other was at Sleeping Bear Dunes on the east shore of Lake Michigan. Over cast and cool ( 40s and 50s) all four days.

I saw similar battery conditions on both short trips with no supplemental charging ( vehicle or 110V). My conclusion was that the 60W was not enought to keep up with the demand.

I see couple plans of action

A) add a power meter
B) look at wiring, it was supposedly done by a reputable company (name withheld) in AZ prior to my purchase
C) Verifiy output at regulator and solar panel
D) verify power consumption from Fridge

Based on this I should be able to fix the issue.

I'll add more info as we go.