Rubicon Solar Power Experience (1 Viewer)

[sheepdawg]

I'm far from an electrical engineer but I just bought a 30 watt portable solar panel to attach to my battery and help keep my ARB fridge going. I was also at the rubithon this year and it seemed I had to start my 40 up once a day otherwise I was getting low. I did not have any monitoring devise, other than what was on the fridge, but now I am thinking that 30 watts may be to small when compared to your 100 watt system. Then again, space in paramount in a 40 and the 30 watt panel folds up nicely.

What are your thoughts? Too small?

 

[Cruiserdrew]

I'm far from an electrical engineer but I just bought a 30 watt portable solar panel to attach to my battery and help keep my ARB fridge going. I was also at the rubithon this year and it seemed I had to start my 40 up once a day otherwise I was getting low. I did not have any monitoring devise, other than what was on the fridge, but now I am thinking that 30 watts may be to small when compared to your 100 watt system. Then again, space in paramount in a 40 and the 30 watt panel folds up nicely.

What are your thoughts? Too small?

Yes, helpful but too small. Your fridge uses somewhere around 20-25 amp-hours per day (and possibly more). A 30 watt panel in good condition with an efficient charge controller will make about 1.5 amps into the battery for about 8 hours per day. So you're only replacing 12 amp-hours (roughly) and consuming 25 amp hours (roughly, lots of assumptions), so you can see you're way off. And that assumes your panel is in full sun, oriented properly and your charge controller is doing it's job.

The best $20 you will ever spend on your system is to get a power meter like this:
http://www.amazon.com/GT-Power-Anal...pebp=1440507559744&perid=02VYKDAFB9Y64B0GYCVN

It goes in-line anywhere you choose in your system and keeps track of cumulative power use, voltage, mins and maxes. I put power poles on mine so that I could put it anywhere, like between the fridge and the source, let it run for 24 hours to measure fridge consumption, or between the controller and the battery so I'd know how much current and power was flowing into the battery. I also could install between the panel and the controller to look at the controller's efficiency (surprisingly good). Anyway, highly recommended, and it makes figuring out your system easy.

I also found it helpful to install voltmeters to keep a rough track of battery state of charge, but you can also do this with a hand held meter. 12.8 is full charge, 12.2-12.3 is 50% charged, 11.8 is fully discharged.

 

[Cruiserdrew]

Here are some random pics of said power meter. Volt meters during install too. Last shot is the project box that holds my charge controller and the Anderson power poles that I use to hook it all up.

 

[sheepdawg]

Nice. Thanks for the tips.

 

[PabloVTA]

did you run a CPAP machine for a giant , by chance?
I wonder how well it would do that.

can yo upost a pic of your cables? I like the idea of using a 10 Ga. extension cord...can handle the abrasions better on the granite.

 

[KT40]

Curious Andrew,
I have the same Blue Sea ACR in my 40. Just picked up a 100 watt panel. Do you disconnect the secondary battery from the ACR once you are set up at camp? In other words, if you don't, does it back feed (acr led light reading combined) to the primary battery and charge that as well? If it did back feed, does that damage anything?

 

[Cruiserdrew]

No-there would be no reason to disconnect the ACR. Your house battery is going to charge until it reaches 13 volts, then the relay will close and also top up the main battery. If you have discharged your house battery, it will take a significant period of charging before it will hold 13 volts and until that happens, the relay stays open and the batteries isolated.

The ACR is built so the A and B side are interchangable and no harm comes "backfeeding" through it. That's kind of normal.

THe ACR itself is built for continuous duty (I called Blue Sea and asked) so no issues there.

 

[KT40]

No-there would be no reason to disconnect the ACR. Your house battery is going to charge until it reaches 13 volts, then the relay will close and also top up the main battery. If you have discharged your house battery, it will take a significant period of charging before it will hold 13 volts and until that happens, the relay stays open and the batteries isolated.

The ACR is built so the A and B side are interchangable and no harm comes "backfeeding" through it. That's kind of normal.

THe ACR itself is built for continuous duty (I called Blue Sea and asked) so no issues there.

OK, good to know. Great info here, thanks!

 

[Semi Hex]

Old thread, but I really like the Anderson Power Poles that you are using. I am not however sure if you ended up liking the 45 amp or the 50 amp connectors best for your application needs. I too will be running 10 gauge wires for my solar and other appliances. I really like the plug in anywhere and noticed you did not use the black/red bonded ones, I assume for interchangeability.

 

[Cruiserdrew]

@george_tlc @alia176 @TrickyT or any one else who might know.

I am adding to my 100 watt folding panel a 160 watt rigid panel on the roof. Also adding a 20 amp MPPT charge controller. The panels differ slightly in their open circuit voltage:

100watt panel--VOC = 21.6 volts
160watt panel--VOC = 23.2 volts

They also differ slightly in VMP:

100watt panel--VMP = 18.0 volts
160watt panel--VMP = 18.7 volts

Will there be any problem paralleling these into the new charge controller?

I realize the 160 watt panel alone is plenty for my needs, but just playing around with it, I know I am going to want to try this, but don't want to damage anything. I'm thinking in marginal conditions could it be hooked up like this?

 

[Cruiserdrew]

@george_tlc @alia176 @TrickyT or any one else who might know.



Will there be any problem paralleling these into the new charge controller?

So I answered my own question today and paralleled both panels at about 3pm in the afternoon, so well past the power peak of the day. It works great! The 2 panels paralleled were pushing 14 amps into the batteries at 13.5 volts. I did notice that the controller decreased the maximum power point from 17.7 volts with the big panel alone to 16.9 volts for whatever reason.

Now I need to run them in series and see what happens. HMMMM need to build some single power point jumpers.

The Max input voltage of the controller is 45 volts, so right at the VOC of both panels.

And anyone who has the Eco-Worthy chinese MPPT20 controller-did you notice the absorb phase is very short?

 

[TrickyT]

14 amps, geez. You'd think you planned on running power tools or a 100W ham transmitter, not just trying to recharge due to running a measly refrigerator overnight. The rest of us should just leave our panels at home and you can provide the power for everybody on the trip. What do you charge per KWH, anyway?

 

[e9999]

vague recollection is that if you connect 2 different panels, the system somehow will run at the lower capacity of the 2 but that could be a function of the wiring system chosen. Not sure.

 

[PabloVTA]

14 amps, geez. You'd think you planned on running power tools or a 100W ham transmitter, not just trying to recharge due to running a measly refrigerator overnight. The rest of us should just leave our panels at home and you can provide the power for everybody on the trip. What do you charge per KWH, anyway?

a quad shot americano before 6:30 AM...and that first piece of bacon.

 

[Cruiserdrew]

Here is the new 160 watt set up. Removable LED camp lights present too.

 

[Semi Hex]

A potential of 13 ahs? I'm most likely wrong with my calculations. I would have to change my controller.

 

[Cruiserdrew]

As a practical matter, you really only get 5-6 amps per 100 panel watts. I'm expecting right around 10 at high summer and low battery. I have 10 amp and 20 amp charge controllers, so will be careful until I know for sure.

 

[opg4759a]

Any concerns with damage to the panel on the roof like that?

I'm considering doing something very similar.

 

[Cruiserdrew]

Any concerns with damage to the panel on the roof like that?

I'm considering doing something very similar.

Not really. I don't think it will be damaged, and every RV on the road seems to have multiple panels these days. But it's a risk, and the panel is replaceable, so worth the risk. I'll know more after June when it has to survive the Rubicon again. Once in camp, it's safer up there than a panel deployed on the ground.

 

[Dragos80]

That's a great power/price ratio.
HF sells their 45 tri-panel for $200.

I like the setup LS1FJ40 has on his new truck. The panel slides out from underneath his roof rack, for added protection.