quote:

Originally posted by Bill Joyce:
I was told that one way to increase the usefulness of the Outback MX-60 was to wire the panels in series to increase the voltages since it can handle 72 volts. If you wire two panels in series you have 34 volts incoming, so some shading will still get you above the 14 to 15 you need. Not having infinite money, time and roof space I can't directly comment.

Good point, Bill. A lot of controllers can use high voltages and step them down to a proper charge voltage. The newest Morningstar ($100 MPPT) can use 75V even.

It also allows you to use lighter wire for the same cable run and/or avoid line losses.

What I'm seeing too, is that higher voltage panels (the real $$$ of a system) are both more plentiful and cheaper per watt. When I buy mine, I'll go a higher voltage for the same dough. Of course then I'll have to change my choice of controller

Anybody think a nominal 24V or 48V panel with an MPPT controller is the cat's meow?

I'm pretty sure my Solar Boost 50 had a shunt connection to measure the charge amps directly. It is too big a unit for you but for a larger system it is worth looking at.

quote:

Xantrex C40.

rvMikey,

I've used lots of the C40's. Had one on my last rig. I have a C60 I just bought for this rig...have not put it in yet. All that you have stated are the reasons I like the C40/60. Price/performance, and the ability to tune the controller are important considerations. Especially in my case, as my system is supplied by 4- KC120's. As you probably know, these don't have an excess of voltage available. My experiments with these panels with smaller MPPT controllers show NO BENEFIT. I have never tried an OUtback on my own system.

If funds were unlimited then I would not have the "moderate" system I have. I've installed lots of systems that gave me "solar envy". But my system works well for me. I boondock as long as I want.

I can tell you, though, that a properly set up MPPT system - with the right panels - can show substantial benefit.

quote:

Originally posted by rvMikey:
Anybody think a nominal 24V or 48V panel with an MPPT controller is the cat's meow?

I am very pleased with my MX-60. The options available to tweak the charge settings in incredible. I purchased five 24V, 160W panels for a total of 800W. We have all the power we need for unlimited boondocking any time of year while living our power hungry lifestyle of satellite internet surfing, watching two Hi-Def TV's (one a 42 inch) and DVR's. The setup was not particularly inexpensive, but the results have been worth the cost IMO.

Yes Jack, our flat 1200W Sanyo (60 Voc) solar panels plus the two MX-60s produce 96A DC current at peak solar condition. I am very please to see the output is that high at the bulk charge mode.

quote:

Originally posted by Jack Mayer:

quote:

Xantrex C40.

rvMikey,

All that you have stated are the reasons I like the C40/60. Price/performance, and the ability to tune the controller are important considerations.
If funds were unlimited then I would not have the "moderate" system I have. I've installed lots of systems that gave me "solar envy". But my system works well for me. I boondock as long as I want.

I can tell you, though, that a properly set up MPPT system - with the right panels - can show substantial benefit.

Well, OK then, Jack. If you read my first post on this topic and now my last, I'd say I have learned about solar stuff, right?

Anyway, it was gratifying to see all the input from all you experts and now I can pass some of this knowledge along in my travels.

Thanks a bunch to all.

I have 3 pairs of Kyocerra 130 12VDC panels, each pair wired in series for 24 VDC, but they'll read 41 VDC w/o a load.

The optimum MPPT benefit occurs when the panels are cool in full sun pumping at the max, and the batteries are low.

The way I understand it, the higher the disparity between the voltage of the panels and the voltage of the batteries, the more benefit of MPPT.

This may be overly simplistic but the more voltage difference between the panels and the batteries, the more extra volts that can be swapped by the MPPT for use as Amps/charging current.

So it may make sense with an MPPT controller to use panels with higher voltage than the batteries to pick up some charging amps in the translation...

The highest that I've seen mine bulk charge is 48-49 Amps DC, but I haven't yet run them in full summer, direct overhead sun, conditions.

Back in April the system floated my batteries in one day after being drawn down about 320 amp hours.

Battery charging Temp sensor/compensation is important to ensure the batteries are gettng the correct charge voltage.

For example, last winter when the temps were in the 20's my batteries were being charged with 15.2 volts - automatically temperature compensated.

If the charger was hard set to 14.8 VDC they wouldn't have gotten an optimum/complete charge.

quote:

If the charger was hard set to 14.8 VDC they wouldn't have gotten an optimum/complete charge.

"Hard set" is a relative thing. If your setpoint is 14.8 and you have temp compensation then it will charge higher/lower depending on the temp compensation algorithm/battery temp. I would never recommend not using temp compensation if it is available. It really does not add much cost.

That is good performance Phil. I have "solar envy". Want to give me a couple thousand bucks? I'd love to totally revise my system.

By "hard set" I meant w/o temp compensation to automatically increase or decrease chargng voltage according to battery temperature.

14.8 VDC is the usually the optimum for most flooded cell lead acid batteries at 77 degree farenheit.

But, unless your rig is usually within about 3 miles of the S. Calif coast, battery temps are variable.

Flooded cell lead acid batteries can harmlessly vent. However, I wouldn't want to be charging a $1,000 worth of AGM batteries at a hard set point of 14.4 VDC (recommended for 77 degree charging) when in the desert and the batteries are 95 degrees.

Jack, if you already have 4 ea, 120 Watt panels, then just add two more panels and you are there - maybe even less if using those AM Solar panels.

Then, with the solar tax credit, it'd be under $1,000 to be virtually generator free! With these fuel prices hw can you afford not to?

quote:

Originally posted by Jack Mayer:

quote:

If the charger was hard set to 14.8 VDC they wouldn't have gotten an optimum/complete charge.

"Hard set" is a relative thing. If your setpoint is 14.8 and you have temp compensation then it will charge higher/lower depending on the temp compensation algorithm/battery temp. I would never recommend not using temp compensation if it is available. It really does not add much cost.

That is good performance Phil. I have "solar envy". Want to give me a couple thousand bucks? I'd love to totally revise my system.

Yeah, Phil, two panels at 600+. (No more solar deduction) Plus a new controller (it would be an Outback). Plus some more batteries - my current bank is four golf carts (I could still add 2 more if I reorganized the compartment - I have not had these too long for that). Adds up to a couple grand. When can I expect your check?

Cheapest, most practical change would be to rewire my 4 panels in series/parallel and add the Outback. Then 2 more batteries. Could get away for a grand....but what I have works...I have to resist the temptation to "fiddle with technology". I do that on selected others rigs...

I could be msitaken but the MX-60 is being upgraded with a controller that works beter with wind power generation. There may be some good deals for the original MX-60 out there.

I am now definitely on "Technology Probation." For example, I just got in trouble for getting new flashlights.

The DW doesn't appreciate how we can save $$$ by eliminating the need to replace flashlight batteries by using rechargeable flashlights like the Pelican 7060 and the Streamlight Strion.

Anyday now, the stuff is going to hit the fan around here when UPS arrives with our new Garmin nuvi 760 GPS...

Hey, I am only being Patriotic and helping my nation by complying with the incentives of the President and Congress of the U.S.A. to spend that tax rebate...

I got my major "technology fix" (solar, inverter, battery, EMS and generator), in "under the radar," by including most of it in the financing for the new 5'er.

I bought it all in advance at the cheapest cost possible over the internet. Then brought it all with me when I went to take delivery of my new rig at RV Sales NM, my Excel dealer. The Techs and I worked 4 days installing it all.

They know the best ways to integrate it all with the Excel's electrical system, fishing wires, etc. while keeping things within warranty - they did a beautiful, clean/solid job.

Now I just have to find a way to get a blue flame heater. They are prohibited for sale in California.

Outback has the new FLEXmax 80 controller that will handle 80 amps vs 70 amps output of the Outback MX-60.

Although it mentions hydro turbine power, it doesn't mention wind turbine power.

The MX-60 doesn't appear to be reduced in price. I got mine for less by getting a couple of dealers engaged in some "price matching."

Maximum Solar Array: 12 VDC systems 1250 Watts / 24 VDC systems 2500 Watts / 48 VDC systems 5000 Watts / 60 VDC Systems 7500 Watts

http://store.solar-electric.com/oufl80sochco.html

quote:

I am now definitely on "Technology Probation." For example, I just got in trouble for getting new flashlights.

Yeah Phil, I can understand that....I just got a Strion as a gift from someone who I put a Wilson trucker, amp and power in for. I did not charge her for the 4 hrs labor and she sent me a Strion. A VERY NICE gift. I love that flashlight.

As for the Blue Flame - come on over to CO and visit me and you can ship the Blue Flame here. I'll help you plumb it. Nice and cool in the mountains. Lots to do, too. You need a "vacation".

I love it there. Last year this time we were very close to moving to Colorado Springs - even went house hunting in Monument..

But my wife chickened out, scared of the winters and snow.

I don't know where she ever got the idea that she would get stuck shoveling all the snow...

Now we're looking down in Texas Hill Country NW of San Antonio...

Jack,

With my 4x130's and Solar Boost 50 I see 25-35A, depending on how low the batteries. The 130's are rated @ 7.39Ipm, 8.02Isc, 21.9Voc, 17.6Vpm, so I am getting some boost. Question, if I wired the 4 panels in two pairs, would I see more charging amps with the Solar Boost 50. Or is amps, amps? Like batteries, 2x6vdc you double voltage, but the amps remain the same.

Phil,

Have you looked around Lake Livingston, in Trinity County. Westwood Shores, 18 miles east of Huntsville. Tax rate of 1.1%

Jim