Solar Show and Tell

[ggreen63304]

Love all the test data and pictures you've given in this thread, but no where did I find the type of battery you are using for storage. 6v, 12v, AGM, LifeP04,or regular lead-acid batteries. Since there are differences in charge rates for different batteries, that will give us a better feel for your system.
Thanks!

[ggreen63304]

After thinking a bit, you are very likely not using LifeP04 batteries because of all the references to the voltages.

[AirMiles]

What batteries? A pair of Duracell EGC2 wet-cell batteries which are relabled high quality Deka/East Penn GC15 golf cart batteries. Wired in serial to get 12 Volts with 230 amphours.

Yesterday, my solar panels produced 1.65 Kwh. Divide that by 12.6 volts is 138 amp-hours. This is the most wattage the system has produced in one day and was pretty much maxed out for getting the batteries fully recharged since it was bulk and absorbtion for all but 20 minutes of production.

I also learned that my system starts charging as soon as it's bright enough to create one Watt of solar. This happened at 6:30 am in Dallas Texas this morning. With the series-parrallell wired panels, the voltage is great enough to start charging at daybreak.

[wulfraat]

Got a full day of Colorado sunshine today and was able to conduct an output test (my 600ah lithium bank was at 62% this morning).

4kwh generated by the panels.
Peak output of the array was 759 Watts
~210ah returned to the battery bank with a couple things running in the trailer (batts were at 97% at 5p)

I was surprised to see peak output so high with flat panels - I’ll take it!

[AirMiles]

Originally Posted by wulfraat

Got a full day of Colorado sunshine today and was able to conduct an output test (my 600ah lithium bank was at 62% this morning).

4kwh generated by the panels.
Peak output of the array was 759 Watts
~210ah returned to the battery bank with a couple things running in the trailer (batts were at 97% at 5p)

I was surprised to see peak output so high with flat panels - I’ll take it!

Very nice Wulfraat! Glad to see your output numbers are about equal to your panel wattage in Colorado.

Wow, 759 Watts! I don't know what I would do with all that wattage. My experience has been that even though my system is capable of producing 400W, it rarely happens because my batteries are recharged early in the day before that much power can be produced. I'll post some pictures next to show what my system produced in the past 10 days of actual boondocking usage.

[AirMiles]

Results from our 10 day trip from Florida to California and back. Our multi-month solar boondocking adventure was cut short due to a family medical emergency. Therefore, this will be the last real-world results from this trip. An interesting day from these results is "five days ago" when we spent two nights (one full day) in an extremely shady site at Ten-X Campground near the Grand Canyon. The battery was fully recharged, but never "floated" on that day. We had the heat on for those two nights as the temperatures dropped to the 30's.

Another interesting fact learned during this trip was that the 3M VHB tape and SikaFlex mounting system can withstand extreme headwinds combined with interstate highway speeds. We did not have the luxury of waiting out strong headwinds on our emergency return trip. We have now fully tested the strength of this mounting system and it worked perfectly.

[Paprika]

"With the series-parallel wired panels, the voltage is great enough to start charging at daybreak."

And that's a big advantage of that configuration. Solar controllers don't start working until the voltage from the panels exceeds a certain threshold. With panels wired in series, the voltage is doubled, so that threshold is reached much sooner in the morning, and charging continues later into the afternoon before the voltage drops below the threshold. In short, the usable "solar day" is extended on both ends.

[AirMiles]

Here is a picture of the shady campsite at Ten-X Campground from "five days ago" where the batteries fully recharged even at the shady site. The series-parallel solar configuration worked great in all situations of this 10 day boondocking adventure. I will post more performance screenshots on future longer-term boondocking situations and look forward to more posts from others documenting the performance of their solar systems on this thread.

http://www.airforums.com/forums/f42/...ml#post2111225

[wendyanddick]

We have a 28 ft Flying cloud. Looking for suggestions for alternate power supply for boon docking. Generator verses solar. Any input would be greatly appreciated

[AirMiles]

Originally Posted by wendyanddick

We have a 28 ft Flying cloud. Looking for suggestions for alternate power supply for boon docking. Generator verses solar. Any input would be greatly appreciated

I have 400W of solar and a Champion 3500W generator (model 100263). The Champion is a quiet inverter-type generator that I run only on Propane from the Airstream quick-disconnect port. A couple of things I have learned . . .

The generator does not recharge the Airstream batteries very efficiently with the stock battery charger (converter). My stock converter only output 13.6V. At that voltage, it would take days to fully recharge the stock batteries and it would only "float" my golf cart batteries. Therefore, I replaced the stock converter with a PD4655 which can "bulk" charge using the generator. With the PD4655, the generator should be able to "bulk" charge the golf cart batteries back to 90% capacity fairly quickly (2 to 3 hours of run time). If you are considering using a generator, a converter upgrade should be considered to shorten charging time.

I don't have too much experience with the solar yet. So far, I've pretty much stayed in sunny locations and the solar easily kept my batteries fully charged. The solar also fully recharged my batteries on my one full day in a shady site, but without much charging time to spare. From my limited experience, it appears 400W of solar running through the factory pre-wire has worked well.

On my 25', I think four 100W panels, with one mounted on each corner, is a great arrangement because there are no shading issues from the AC unit. I'm not sure of the roof layout on a 28'. Maybe you can get 600W up there without AC shading issues, run 4 awg to the controller and wire in parallel. I know Rocinante just put 650W on his 27' and is very happy with his results.

I hope this helps, there are lots of decisions to be made when customizing an Airstream's battery setup. One must consider their needs, how they will use their Airstream, and custom design the battery system to their needs. My battery and solar system worked perfectly on my 10-day no-hookup adventure to California and back. We will soon see how it works in shady situations when I spend time near Smokey Mountain National Park later this summer. Stay tuned, I will share my results on this thread as I get them.

Also, my solar system cost $2,400 with four SP100 AMSolar panels, wiring, Victron 100/30 Controller, PD4655 Converter, two Duracell EGC2 golf cart batteries, mounts, fuses and circuit breaker.

Also, I hope others will post their actual solar results on this thread so we can all learn how these solar systems perform in various locations and conditions.

[wulfraat]

Originally Posted by wendyanddick

We have a 28 ft Flying cloud. Looking for suggestions for alternate power supply for boon docking. Generator verses solar. Any input would be greatly appreciated

Difficult question to answer without knowing what you are looking to achieve when camping off Grid. You can spend $1000 or you can spend $25,000 for an off grid boondocking energy solution.

If you are not sure what your needs are, I'd very much recommend getting a simple, small generator and starting there. Once you have been out in the wild a bunch you can start evaluating what works for you and what doesn't when running with a generator, and then start to design a system from there, if needed.

[AirMiles]

Good answer Wulfraat! I've used generators to keep my batteries charged while off the grid for the past three years. Just the generator, a set of golf cart batteries, a PD4655 controller and a blade battery cut-off switch would have met my past occasional boondocking needs. The cost of that setup would be $1,000 for a generator, $200 for batteries, $200 for converter, and $50 for the blade cut-off switch and wiring, totaling $1450. Even if you add solar later, all of these items will still be useful. I carry my generator with me even with the solar. On my 10-day trip, I used the generator to run the AC for a few hours in Biloxi, MS and Shreveport, LA. I didn't need the generator for battery charging on that trip, but I sure needed it for air conditioning at those two locations!

[InterBlog]

All of this is our own DIY (myself and mostly my husband):

(1) Solar blog posts - details here, and solar money shot, 2007 Airstream Interstate:



(2) Inverter, batteries, and general layout with some of the peripherals:




The system was sized to run my off-grid office, plus everything else we've got in the way of Interstate upgrades. Our rig is no longer electricity-limited. We never run out of electricity, even with my large computer work station. Depending on how much time we spend off-grid, we might come up short on propane or water, but never power.



I've begun writing blog posts to capture all the lithium system details, but other projects keep intruding and preventing me from finishing the series. Here is Part 1 (general description) and Part 2 (AC system) for starters.

Part of the lithium build is also discussed in an epic Air Forums thread here, but there's a lot of sideways chat in that one. Plus some of the decisions were OBE and details updated from that.

[SilverHouseDreams]

Our 2011 22FB has some older Zamp 85W panel, I was happy to see it hit a peak yield of 80W under the Oregon sun and my best day (since installing the Victron charge controller 5 days ago) was 230Wh. We did a trip this weekend where I left the converter disconnected from shore power to see how well solar and our BattleBorn battery would keep up, seems safe to say that we should be able go for a several day boon docking trip as long as we have some sun. It helps that we are pretty frugal, we don't watch TV...and we didn't need the fan much on this trip, but we did have the furnace running pretty warm at night and exterior temperature in the mid-30s to low-40s. We did have the fridge on AC power, as it had failed to light on propane (later to be determined due to spider nest within the burner assembly).

I am now debating between a 100W or 200W portable panel, at this point we will see how another trip goes where we have AC available but will leave the converter off since that works for our next scheduled outing.

[AirMiles]

"Our 2011 22FB has some older Zamp 85W panel, I was happy to see it hit a peak yield of 80W under the Oregon sun and my best day (since installing the Victron charge controller 5 days ago) was 230Wh."

Thanks for sharing SilverHouseDreams. So far it seems common that peak solar panel wattage is equal to the panel rated wattage in many parts of the country. I thought reaching panel wattage might have been a Florida characteristic or a Southern characteristic. I'm happy to see it can also be achieved as far north as Oregon.

I also compared your system's best days to my 13 days of real-world data. There was one day where I got 4 times the total solar panel wattage and one day where I got 3 times like yours. Most days were in the two times category. I believe the lower panel watt hours produced on sunny days is mostly due to lower battery charging needs. Four times my panel wattage equals 1600 Watt hours. Dividing 1600 Watt hours by 12.6 Volts equals 127 Amp hours. 127 Amp hours is probably close to the maximum my 400 watt solar system can produce on a sunny real-world day when my 230AH battery is deeply discharged. 127 divided by 230 is 55% discharge on my battery, which is more than is typically recommended for battery longevity.

Let me share my thoughts on depth-of-discharge (DOD). The Deka/East Penn life cycle chart for my GC15 golf cart batteries shown in this article http://www.pbase.com/mainecruising/d...battery&page=1 states these batteries lab test at 1,000 cycles at 50% DOD and around 600 cycles at 80% DOD. This lab test tells me these batteries are good for a certain amount of Amp hours over their lifetime and there's not much difference in lifetime total Amp hours produced at different DODs. 1000 times 115AH (50% DOD) equals 115,000 lifetime AH. 600 times 186AH (80% DOD) equals 111,600 lifetime AH. There's not much difference in lab rated lifetime Amp hours between 50% DOD and 80% DOD. Therefore, I'm going to treat my batteries like propane exchange tanks, draw them down as far as 80% DOD as needed and replace them when they run out of juice. I'm willing to test this theory out in the real world with my $200 worth of golf cart batteries. We shall see how this goes and I will report the results, good-bad-or-ugly, on this thread. On my first 10 day trip, my greatest DOD was 55%, so maybe I will never need to go to 80% DOD.

Stay tuned for more real-world solar results and thank you InterBlog for sharing your system with us on this Solar Show & Tell thread!

[thiel]

Believe it or not I have not have a chance to do a really full or scientific test with the solar, but I do have some observations.

I have 4@100w panels mounted on the roof... they are not straight up (flat) but rather tilted to roughly follow the slope of the roof (so all four never point perfectly in the same direction). I have two Group 27 Lead Acid batteries. All panels are wired parallel.

-- I get current at daybreak, at dusk, and when it's raining.

-- In a shady campsite with the sun just punching through the trees a few times a day, I'll still see my batteries returned to full charge by 2pm or so (and that's while using the inverter to charge laptops and such.

-- In full sun (I'm on the Canadian border right now, so it ain't overhead), with dirty panels, I'm seeing wattages of 350w or s. I'd say that's pretty good--and shows that my tilted panels don't have too much of a penalty associated with them. I expect that if I was a bit further south with the sun right overhead, I'd be really close to the 400w max.

[AirMiles]

Thiel, My panels too are slightly tilted in opposite directions following the contours of the Airstream roof. Mine are wired series-parallel. The two opposing tilted panels on the front in one series and the two opposing tilted panels in the rear are the second series. I even attempted to make them flatter by drilling a lower hole in the inside roof mount brackets. It appears there is not much loss from not being mounted perfectly flat. I've also read that having a slight tilt on the panels helps keep them clean as the rain washes the dirt off the slightly-tilted panels. I think with my series-parallel arrangement, its important to have a matched set of opposing panels so that the MPPT calculation uses the same maximum for both sets of series wired panels.

I'm looking forward to seeing more results from your tests so we can compare notes between a full parallel and a series-parallel installation.

[mythbuster88]

Originally Posted by Rocket53

I recently replaced my old factory solar controller with an Victron smart solar along with the BMC-712 monitor. I haven’t had it out of the storage facility to start recording readings. What numbers should I be seeing in full sun? Depends on the panels right? I have the one 55 watt panel.

Rocket, with my stock Airstream solar (2X80W panels) the Victron MPPT 100/30 does not output any current. i.e., it never turns on.
Fine print reading of the specs require battery voltage plus 5 Volts to turn on and my stock solar panels never get there.

So it is a voltage thing and it depends how many volts your panel produces.

[SilverHouseDreams]

Originally Posted by mythbuster88

Rocket, with my stock Airstream solar (2X80W panels) the Victron MPPT 100/30 does not output any current. i.e., it never turns on.

Fine print reading of the specs require battery voltage plus 5 Volts to turn on and my stock solar panels never get there.



So it is a voltage thing and it depends how many volts your panel produces.

What are your battery settings in the MPPT? You say it never turns on, what does it actually reflect it is doing. What panel voltage does it report? With my Li batteries my voltage is pretty high, but even at 95% SOC I can readily get the charger to go into bulk mode.

[AirMiles]

MythBuster, can you rewire your two 80W panels in series? Wiring them in series doubles the voltage so the Victron MPPT will turn on. Its also cuts the Amps in half, which greatly reduced voltage loss over the factory prewire. The Victron Manual actually recommends series paired panels as most efficient for the controller: " Recommended number of cells for highest controller efficiency: 72 (2x 12V panel in series or 1x 24V panel) "