Solar Show and Tell

[mythbuster88]

Originally Posted by 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) "

Thats my next project.

[mythbuster88]

Originally Posted by SilverHouseDreams

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.

Sunny southern California max voltage is 15 Volts.
I am going to rewire the panels in series and see what happens.

The factory panels never did work very well. The most I ever saw was 4 amps before I switched the controller.

[mythbuster88]

Originally Posted by 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) "

Series operation did the trick. However the 80W panels are not. Turns out that Airstream put in 50W panels. I have whopping 2 Amps at noon here in sunny Redondo Beach.

[AirMiles]

Originally Posted by mythbuster88

Series operation did the trick. However the 80W panels are not. Turns out that Airstream put in 50W panels. I have whopping 2 Amps at noon here in sunny Redondo Beach.

2 Amps? Ouch! Did you replace that skinny little 14 awg wire and fuse, between the new Victron controller and bus bars, with at least 6 awg and add a circuit breaker? If not, that skinny wire could be restricting your amperage. Even 100 watts of solar is capable of producing 7 amps of output with a Victron 100/30, at the equator, at solar noon, with a cloud-free sky, and 77 degrees temperature! Seriously, I would expect to get at least 5 Amps from 100 watts.

Is your battery fully charged? If your battery is fully charged, it may only accept 2 amps in "float" or "absorption" mode. Turn on some DC load, such as your fantastic fans, inverter, lights, range hood fan . . . and see if the Amps go up.

[mythbuster88]

Originally Posted by AirMiles

2 Amps? Ouch! Did you replace that skinny little 14 awg wire and fuse, between the new Victron controller and bus bars, with at least 6 awg and add a circuit breaker? If not, that skinny wire could be restricting your amperage. Even 100 watts of solar is capable of producing 7 amps of output with a Victron 100/30, at the equator, at solar noon, with a cloud-free sky, and 77 degrees temperature! Seriously, I would expect to get at least 5 Amps from 100 watts.

Is your battery fully charged? If your battery is fully charged, it may only accept 2 amps in "float" or "absorption" mode. Turn on some DC load, such as your fantastic fans, inverter, lights, range hood fan . . . and see if the Amps go up.

I used 10 gauge from the controller to the bus bar ( and everywhere else) It looks like that Airstream used 10 or 12 gauge wire. The batteries may be charged so I'll try again tomorrow when they have discharged a bit overnight.
I have a shade issue so most of the day one or both cheepo Airstream panels are out of the sun.
Here is a picture of the roof. Do you see panel potential? Those panels you used are $254. I'm thinking two.

[AirMiles]

I used 10/2 on the roof, the 10 awg factory pre-wire from the Zamp box to the Victron 100/30 controller and 6 awg from the controller to the bus bars. I'm pushing up to 30A at 14.4V through the 6 awg between the controller and bus bars.

Your 10 awg between the controller and bus bars is probably not an issue with only 100W in panels pushing 7 Amps at 14.4 Volts for just a few feet. But you will want to increase the wire size between the controller and the bus bars to add an additional 200W in panels. With 300W of solar panels, you should be pushing 20+ Amps at 14.4V.

I have no experience running mismatched panels on the factory pre-wire. I believe if you run the panels in parallel, you will be pushing a lot of amps at low voltage on the pre-wire. I believe running mismatched panels in series is also not a good idea. All I know for sure is that my four 100W matching panels work great over the factory pre-wire.

Let us know what happens when you put a load on your batteries. I believe you will see your Amps increase to between 5 and 7 with your 100W of solar.

Also, for anyone following this thread for my cross-country solar boondocking test, I will be resuming my trip tomorrow!

[mythbuster88]

Originally Posted by AirMiles

...

I have no experience running mismatched panels on the factory pre-wire. I believe if you run the panels in parallel, you will be pushing a lot of amps at low voltage on the pre-wire. I believe running mismatched panels in series is also not a good idea. All I know for sure is that my four 100W matching panels work great over the factory pre-wire...

The factory cheepos are going out to pasture, or the slaughterhouse.

[VanAlcanLol]

I have a 1994 Excella 25' and plan to add solar. I hear the ceiling is pre-wired with 10 ga but like you mention 6 or larger would be good for extra wattage from the solar array. Can you use the 10 ga as a pull wire to draw through the larger wire?

[AirMiles]

I’ve read the 10 gauge cannot be used to pull heavier wire. My 10 gauge works perfectly from the panels to the controller with a series-parallel configuration. I’ve documented 30 Amps of charging early in this thread in full sun and have gotten fully charged batteries in sun, shade, clouds every day for the 15 days I’ve used it. I can’t imagine that a full parallel heavier gauge configuration could perform any better. At my last campsite, only two panels were in the sun at a time and for only half of the day and again my batteries fully charged. I’ll have more to report later as I’m back on my cross-country summer travels. But I’ve yet to not get the batteries fully charged under some fairly challenging conditions.

[HiHoAgRV]

Originally Posted by VanAlcanLol

I have a 1994 Excella 25' and plan to add solar. I hear the ceiling is pre-wired with 10 ga but like you mention 6 or larger would be good for extra wattage from the solar array. Can you use the 10 ga as a pull wire to draw through the larger wire?

I didn't think that '90's trailers had prewire. My 91 didn't show any signs of spare wires inside although I haven't pulled ceiling panels. I added wires down the fridge stack, 4 runs of #8 for a series/parallel 4x 100 w setup.

[rmkrum]

Heh, odd story here--ran all new cables with an AMSolar kit to install our panel, roof penetration, controller, etc. Never even thought to look for pre-wire.

Finally found out about it when I joined the forums...and after a little profitable time spent reading posts by Lewster, was very glad I did not find it. I can add a LOT more panels in parallel with the setup I have with minimal voltage drops...

Sometimes you just get lucky, I guess, by simply being unlucky.

BTW, on our 2007 International CCD 22 footer, supposedly the factory prewire comes out near the front Fantastic Fan (unconfirmed and don't care) and under the bed in the front (confirmed and ignored)

[AirMiles]

RMkrum, you are right that the factory pre-wire is most efficient with either 200W of series connected panels or 400W of panels in a series-parallel arrangement. I have four AM Solar SP100 panels in two pairs of series connected panels that is extremely efficient and effective on the factory pre-wire as documented earlier with pictures in this thread. I believe you have nine-hundred watts of panels which is well beyond the capacity of the factory pre-wire. I’d like to see pictures (or links) documenting the effectiveness and efficiency of your systems, which is the purpose of this Solar-Show&Tell thread.

[AirMiles]

Someone previously asked how my Champion 3400W Dual Fuel generator worked at elevation using the Airstream low-pressure quick disconnect port. This week I ran my convection microwave on my generator at 8500’. I also ran my AC for about five hours at 6500’. Both times the setup worked perfectly.

I’ve also been charging my batteries with only my 400W of solar for the past 15 days in some difficult shade situations and am happy to report that my batteries “float” each day. I’ll be posting a graph of the results when I get 30 days to report. The system rarely uses more than 250W daily to recharge the batteries because they are done bulking before the sun is near peak and well into absorption with declining Amp requirements. It appears to me that 200W of solar would be adequate for my needs on most days, except if in shade or clouds. But I’m satisfied to have the 400W for shady or cloudy days.

I’ve been out of cellphone range and will probably continue to have little service since I’m wandering around Colorado boondocking to test my solar setup.

[wulfraat]

Had a good test of my system over 4th of July - 5 days of boondocking...

On average without using the aircon I would consume about 250ah of energy per day living life off grid. This was easily replenished by my 800watts of solar each day here in Colorado at ~8,500 feet elevation.

Peak usage day was 692ah of power (ran the AC a bunch) and on that day solar returned 407ah to the batteries.

600ah lithium batts got down to 40% one day but for the most part operated between 65% and 100% SOC.

[tabney0315]

Originally Posted by wulfraat

Had a good test of my system over 4th of July - 5 days of boondocking...

On average without using the aircon I would consume about 250ah of energy per day living life off grid. This was easily replenished by my 800watts of solar each day here in Colorado at ~8,500 feet elevation.

Peak usage day was 692ah of power (ran the AC a bunch) and on that day solar returned 407ah to the batteries.

600ah lithium batts got down to 40% one day but for the most part operated between 65% and 100% SOC.

Just curious, what all did you have on that consumes 250ah per day?

[wulfraat]

Ice maker is always on, multiplus inverter itself, frequent use of microwave, electric kettle, lights, TV for a few hours, WiFi LAN router, various stuff charging all the time, electric fry pan for a bit, just stuff.....

I used to strictly manage to 50amp hours per day when I was on agms.. now I just kinda use the trailer same as if I was on shore power. Energy usage adds up!

[thiel]

Hey folks... silly question: should I be shutting off my solar panels when I'm plugged in for an extended period?

[wulfraat]

Originally Posted by thiel

Hey folks... silly question: should I be shutting off my solar panels when I'm plugged in for an extended period?

It doesn’t matter if you have victron gear that is networked and a CCGX in the system.

It’s smart enough to know when batteries are full and will reduce output of the MPPT controller down to almost zero amps accordingly, even if the sun is blazing [emoji4]

That being said, personally I do not float my lithium’s. Once a month I will bring them up to 100% but otherwise I disable all charging sources while on shore power and let the batteries slowly run down to 50% and then gently charge them back up.... vs keeping them pegged at 100% SOC.

[mythbuster88]

Originally Posted by AirMiles

I used 10/2 on the roof, the 10 awg factory pre-wire from the Zamp box to the Victron 100/30 controller and 6 awg from the controller to the bus bars. I'm pushing up to 30A at 14.4V through the 6 awg between the controller and bus bars.

Your 10 awg between the controller and bus bars is probably not an issue with only 100W in panels pushing 7 Amps at 14.4 Volts for just a few feet. But you will want to increase the wire size between the controller and the bus bars to add an additional 200W in panels. With 300W of solar panels, you should be pushing 20+ Amps at 14.4V.

I have no experience running mismatched panels on the factory pre-wire. I believe if you run the panels in parallel, you will be pushing a lot of amps at low voltage on the pre-wire. I believe running mismatched panels in series is also not a good idea. All I know for sure is that my four 100W matching panels work great over the factory pre-wire.

Let us know what happens when you put a load on your batteries. I believe you will see your Amps increase to between 5 and 7 with your 100W of solar.

Also, for anyone following this thread for my cross-country solar boondocking test, I will be resuming my trip tomorrow!

So we added AM solar 100W panels in series with the cheepo Airstream 50W panels. We did this twice for a 300W total. So I mismatched the panels figuring why not? They are just like power supplies right?

Really works great i.e. lots of solar mojo.

But I just learned we should install a switch/relay/contactor to be able to shut off the panel power to the controller!

[mythbuster88]

Originally Posted by wulfraat

It doesn’t matter if you have victron gear that is networked and a CCGX in the system.

It’s smart enough to know when batteries are full and will reduce output of the MPPT controller down to almost zero amps accordingly, even if the sun is blazing [emoji4]

That being said, personally I do not float my lithium’s. Once a month I will bring them up to 100% but otherwise I disable all charging sources while on shore power and let the batteries slowly run down to 50% and then gently charge them back up.... vs keeping them pegged at 100% SOC.

Why do you do that?
Whats wrong with 100% SOC all the time?