Who has Solar/ what controller/panels?

I was thinking of doing an invertor to the RV panel somehow.

Its probably wrong to backfeed the panel, and have the main breaker off... huh?

Yes, you don't want to just have a hack job from inverter to load center. It usually isn't necessary because you can either plug your shore cord into the inverter or install a transfer switch.

If you're now thinking of powering all of your 120V devices with the use of an inverter, I'd suggest to do some more research about the power needs of such a system. I think you'll quickly find out that 8 amps from a solar module and just a battery or two isn't going to cut it.

Jim in Denver is one of the more adept and experienced solar users on the Forum. You could search through his posts to see how solar is implemented correctly. (Jim, you've got my address, just send the usual check ;) ).

JiminDenver wrote:
I've used three big panels like that with the Eco-worthy 20 amp MPPT controller as portables. They are a pain to store but setting up only takes minutes really. A 250w panel and the Eco-Worthy should deliver around 18a for the better part of the day if you are tracking.

I still have a 230w/Eco-worthy portable but you can see in my signature what we use now.

Just looked up the eco worthy. Looks pretty good and only $99 bucks..

I have to look at specs but I would assume again that it would be best to couple it with a 24 volt panel.

What I read is the mppt controller would double the amps of the 24 volt panel? So that 8.7 amps that 240 panel produces would be around 16-17 amps.

Maybe I would put on the roof of the RV, but I wonder the performance when in the shade....

Probably my load per hour is about 5 amps. TV and a fan. Water pumps use, ect.

I was thinking of doing an invertor to the RV panel somehow.

Its probably wrong to backfeed the panel, and have the main breaker off... huh?


http://www.amazon.com/ECO-WORTHY-Charge-Controller-Regulator-15-30/dp/B00FF1KGT4

I've used three big panels like that with the Eco-worthy 20 amp MPPT controller as portables. They are a pain to store but setting up only takes minutes really. A 250w panel and the Eco-Worthy should deliver around 18a for the better part of the day if you are tracking.

I still have a 230w/Eco-worthy portable but you can see in my signature what we use now.

smkettner wrote:
The $170 (250w) 24v panel gives 8.7 Isc (short circuit amps)
The $159 (140w) 12v panel gives 8.4 Isc so it is about a wash through PWM.
The increased voltage should only help in shaded or partial sun conditions such as early and late or partly clouded.
Just make sure the panel size is OK without getting too close to shade items such as vents or antenna.

If you need more power in the future you could swap in an MPPT and get 15 amps instead of the 8.7.

So that is the max amps I would be able to get from the panel in full sunlight? 8.4 or so ISC?

I figure my one 24 volt panel will net similar statistics as above with that renogy PWM 30 amp controller that accepts 48 volts and lower.

And that would be incorrect. If you plan to use a PWM controller and a nominal 24V module, you will be limiting the solar harvest (charge current).
Yes, the 24V module will have higher power density due to the way the individual cells are constructed and the amount of cells but you have to get all of that potential power to the batteries. PWM is not the way to go.

Have you considered the size and weight of the module with your scenario of using it as a portable? These 24V modules are big, bulky, and weigh near 50 lbs. I sure wouldn't want to schlep one around (and don't).

If you need portability, are just looking for battery recharge and powering low voltage devices, a pair of 12V modules is the better solution. You will be able to use one of the budget charge controllers with that system.

If you're looking down the road and thinking of adding modules, are powering more power hungry devices, or need more than 250 W, then the 24V modules with permanent mounting will get you more power/module-space than 12V modules. You will need a pricier controller to make everything efficient.

What I'd suggest you do is calculate or measure your power usage, first. Design for expansion, and permanently install a module on the roof. You will probably soon tire of moving a module in and out and will be asking next about connectivity and theft issues. Hopefully, that occurs before the module is broken or abused from setting it outside with no permanent installation.

The $170 (250w) 24v panel gives 8.7 Isc (short circuit amps)
The $159 (140w) 12v panel gives 8.4 Isc so it is about a wash through PWM.
The increased voltage should only help in shaded or partial sun conditions such as early and late or partly clouded.
Just make sure the panel size is OK without getting too close to shade items such as vents or antenna.

If you need more power in the future you could swap in an MPPT and get 15 amps instead of the 8.7.

This will be a single panel system.

The 24 volt panel IMO would be better then a 12 volt panel on the PWM controller I linked to I would assume.

I know from what I read is that hooking up panels in series and an mppt controller is best. So say a guy have 3 24v panels. Hook them in series for 72 volts.

This way you need more volts then the batterys has to charge. So with that set up when the sun just peaks over the horizon say each panel is only producing 5 volts each. The mppt controler will see 15 volts and start charging the batterys.

But I am doing one panel only.

I figure my one 24 volt panel will net similar statistics as above with that renogy PWM 30 amp controller that accepts 48 volts and lower.

Plus the 24 volt panel will compensate for voltage loss through the wiring. Although I will be less then 4 ft from the batterys with the controller. The panels will have a 15 ft tether and be portable that I can move it around in the sun.

Ill do 6 gauge from controller to batterys. From panel to controller I am not sure what size I will use...

I have a single 235W panel but use the Morningstar MPPT-15 controller. The Morningstar controller cost was $200. It has a fully programmable interface and battery temperature compensation. You would have to decide if fiddling with the controller to set float voltage continually, the absence of temperature compensation, and the loss of 50% amperage is worth the higher price of a quality MPPT controller. I decided the added battery longevity and the programmability is worth the additional price.

rjxj wrote:
Read Handybob blog.

And http://www.jackdanmayer.com/rv_electrical_and_solar.htm and http://www.amsolar.com/home/amr/cpage_9/rv_solar_education.html

Bogart sc2030 solar controller. Bogart trimetic system monitor playing with the sc2030. Four cynergy 230 watt panels. Four Sammys club gc2 batteries.
I power my ac, microwave, hairdryer, toaster with a honda 3000 remote start. I invert with a xantrex 600 for 2 televisions and misc small junk.

You will read all sorts of arguments and some will insist that mppt is the only way to go and you will get 30% more harvest. Others say you will be lucky to get 10% and its only under ideal conditions. Some say its better to go mppt on larger systems over 600 w. Some say you can get more bang for your buck by just adding one more panel to a pwn system.

I chose 12 v panels with a narrower width in case I change rigs someday. 24 v panels seemed to often be more square. I had considered 24's but bought 4 panels delivered from solar blvd for $620 i believe. Either way buy quality. Read Handybob blog.