Winter solar supply

[AJMike]

Our Winnebago Fuse (2018.5, 23T) came with 2 SolarPower flexible 100 watt panels and we added a third. Last summer when we were dry camping here in the south west we typically would see 15-16+ amps coming from the panels (as shown in the OnePlace) but we have not seen more than 8-9 during the Winter, and far less if the day is even a little cloudy.

How much of a decrease in output should I expect from solar panels due to the lower arc of the sun during the Winter? I ask because I am a bit concerned that the summer heat here in southern Arizona might have degraded the flexible solar panels and that perhaps some of the decrease I am seeing is from that rather than from the changed location of the sun.

[Winterbagoal]

Originally Posted by AJMike

Our Winnebago Fuse (2018.5, 23T) came with 2 SolarPower flexible 100 watt panels and we added a third. Last summer when we were dry camping here in the south west we typically would see 15-16+ amps coming from the panels (as shown in the OnePlace) but we have not seen more than 8-9 during the Winter, and far less if the day is even a little cloudy.

I live in southwestern Ontario, Canada and have seen close to 15A on a sunny day early last July, just before I replaced the NAPA batteries with lithiums. The NAPAs were pretty much done after about a year of use.
What I think you're seeing is the number shown in the "A" display selection on the Zamp Charge Controller display, not the One Place Display monitor, which is the Winnebago battery voltage display only, not amperage.
I have also seen all sorts of other amperage/current numbers under the sun (pun intended) depending on the SoC of my batteries, which affects the "A" number. Sun or cloud.
Not long after I got my Navion, and added a 3rd panel, I asked Zamp tech support to explain the 3 display meanings, and this is what they told me. The Zamp Charge Controller display has a button in the upper right hand corner marked "Amp/Volt" that allows you to step through 3 display options. The "A" option shows amps that are allowed to come in at any given moment to your battery bank, and this will be a lot lower if your batteries are very near full. The charge controller sees your batteries and determines how much amperage to let through. Late in the day when the sun is down, but the sky is still light, my display will show some tenths of an amp still coming in. The "Ah" display shows the amount of amps harvested since dawn that day, and the "V" display shows the approximate voltage of the batteries.

Originally Posted by AJMike

How much of a decrease in output should I expect from solar panels due to the lower arc of the sun during the Winter? I ask because I am a bit concerned that the summer heat here in southern Arizona might have degraded the flexible solar panels and that perhaps some of the decrease I am seeing is from that rather than from the changed location of the sun.

Not sure how much sun angle affects amperage to the batteries, probably somewhat, but what your Zamp display is probably really telling you is that your batteries may be very near fully charged, and it is lowering the amperage/current to them, as it's supposed to do when they're almost full. If you're also plugged in to shore power, that will charge them as well. So, you could be in bright sunlight, but only see a few amps coming in if your batteries are closer to full.
Just my interpretations based on some experience with an almost identical solar charging system. Others may offer additional input.

[AJMike]

Originally Posted by Winterbagoal

What I think you're seeing is the number shown in the "A" display selection on the Zamp Charge Controller display, not the One Place Display monitor, which is the Winnebago battery voltage display only, not amperage.

Yes, of course. That is correct. I am seeing the values on the Zamp controller and it is the amperage value that I have been looking at. Typically during our first summer with the flexible panels I would see 15+ amps around noon and more than 100 AH for the day. Now, in the Winter I am seeing much, much smaller numbers for both the peak amps and the total day's AH.

Originally Posted by Winterbagoal

Not long after I got my Navion, and added a 3rd panel, I asked Zamp tech support to explain the 3 display meanings, and this is what they told me. The Zamp Charge Controller display has a button in the upper right hand corner marked "Amp/Volt" that allows you to step through 3 display options. The "A" option shows amps that are allowed to come in at any given moment to your battery bank, and this will be a lot lower if your batteries are very near full. The charge controller sees your batteries and determines how much amperage to let through.

Now I did not know that. I thought that the controller would take all of the charge available and just dump whatever it did not need. What you are saying is that if the batteries are nearly full I should see a lower amp value and perhaps that is what is happening along with the lower angle of the sun.

Several months ago I replaced the OEM batteries with AGM batteries. They have a smaller AH rating than the wet cells, and that worried me a bit, but the higher rated AGMs were heavier than I wanted to risk in the battery support since I did not know how much weight the support itself could safely hold.

Originally Posted by Winterbagoal

Not sure how much sun angle affects amperage to the batteries, probably somewhat, but what your Zamp display is probably really telling you is that your batteries may be very near fully charged, and it is lowering the amperage/current to them, as it's supposed to do when they're almost full. If you're also plugged in to shore power, that will charge them as well. So, you could be in bright sunlight, but only see a few amps coming in if your batteries are closer to full.

These are values that I see when dry camping, but we generally do not stay in one place longer than 2 days so the batteries rarely get very low and the AGMs seem to hold their charge longer. And, of course, when we drive from one place to another we end up charging the coach batteries from the alternator.

I guess I should wait for the summer and see how things go then. Thanks for your help.

[creativepart]

I replaced the Zamp PWM controller with the more efficient Victron SmatSolar MPPT controller with Bluetooth.

Not only do I find it more efficient but the reporting is very helpful.

I know this doesn’t answer the OP’s question, sorry I don’t know the answer. I think it’s a variable that’s longitude/latitude/direction/time dependent.

PS. For those interested in the numbers: The chart attached spans the last 30-days. The first 7-days or so the RV was in storage. Then plugged in at home for 4-days, then in transit to AZ for 4-days and the last 15-days plugged in to shore power. A couple of which were rain days. That tallest bar on the graph was a drive day/boondocking afternoon at a Harvest Host in NM. My batteries have been fully charged the vast majority of this time. Currently on shore power the solar charge controller only supplies power to the batteries when my inverter/charger takes a short break every couple of hours. The three colors on the bars are bulk, absorption and float charging. White is bulk charging.

[Winterbagoal]

Originally Posted by AJMike

Yes, of course. That is correct. I am seeing the values on the Zamp controller and it is the amperage value that I have been looking at. Typically during our first summer with the flexible panels I would see 15+ amps around noon and more than 100 AH for the day. Now, in the Winter I am seeing much, much smaller numbers for both the peak amps and the total day's AH.



Now I did not know that. I thought that the controller would take all of the charge available and just dump whatever it did not need. What you are saying is that if the batteries are nearly full I should see a lower amp value and perhaps that is what is happening along with the lower angle of the sun.

Several months ago I replaced the OEM batteries with AGM batteries. They have a smaller AH rating than the wet cells, and that worried me a bit, but the higher rated AGMs were heavier than I wanted to risk in the battery support since I did not know how much weight the support itself could safely hold.



These are values that I see when dry camping, but we generally do not stay in one place longer than 2 days so the batteries rarely get very low and the AGMs seem to hold their charge longer. And, of course, when we drive from one place to another we end up charging the coach batteries from the alternator.

I guess I should wait for the summer and see how things go then. Thanks for your help.

I had AGMs in my Roadtrek, and they are pretty hardy, especially when drawn down heavily, or in cold temps like I get here. We did more touring than camping for days at a time, so when we drove it, the batteries were recharged. If you drive regularly, 300W of solar will easily help maintain them at full charge, when you're parked. Yes, to the "full batteries, lower angle" question. The A values will be lower.
I just went out and checked my Zamp display. It's been dark here for an hour, so my panel shows A = 0.0 , my Ah display shows I harvested 10.5 amps today, and my V is 13.3V, so somewhere around 90% - 100% SoC. Normal for me, as I always have my inverter on, and a battery charger plugged in to it maintain my chassis battery, plus the usual phantom vampire draws. I can boost the batteries to full easily from shore power by tweaking the PD9245C up to boost with the charge wizard pendant. But it's not necessary to fully recharge lithium batteries after every discharge. So I don't.
I'd wait until the summer and see what transpires. It's tough to determine high and low watermarks in one season. They will change.

[AJMike]

Originally Posted by creativepart

I replaced the Zamp PWM controller with the more efficient Victron SmatSolar MPPT controller with Bluetooth.

How much trouble was it to replace the Zamp controller? The information from the Victron looks really helpful.

[AJMike]

Originally Posted by Winterbagoal

I can boost the batteries to full easily from shore power by tweaking the PD9245C up to boost with the charge wizard pendant.

Please forgive my ignorance but what is a "PD9245C"? And what is a "charge wizard pendant"?

[creativepart]

Originally Posted by AJMike

How much trouble was it to replace the Zamp controller? The information from the Victron looks really helpful.

15 minute job. It’s pretty much a direct replacement. The Victron is slightly larger. The wiring is the same layout. My Zamp had eyelet terminals on the wires. So I just cut them off. The Victron uses bare wires.

On a fuse you might have to be sure you have enough room. It would depend on where the Zamp controller is mounted. I know on some Class B RVs the Zamp controller is mounted on a wall inside with other electronic meters, etc. The Victron is usually mounted out of site in a compartment near the batteries.

On my RV the Zamp monitor was hidden away in a basement compartment. So it didn’t matter.

The Zamp has the wiring connected on the backside out of view. While the Victron has the wiring on the bottom fully visible. Not something you’d want to see on a interior wall.

[creativepart]

Originally Posted by AJMike

Please forgive my ignorance but what is a "PD9245C"? And what is a "charge wizard pendant"?

The PD9245C is a 12v converter charger and the "charge wizard pendant" is a remote control to adjust settings on the device. Most converter chargers are installed hidden away. The pendant puts an external control option somewhere remote of the device to control its functions.

[rarebear.nm]

In the US SW durning the winter you can expect around a 30-35% reduction in solar gain for flat mounted panels. That's why some folks tilt their panels towards the south. Another solution is to install 33% more panel capacity than otherwise needed to compensate for the low sun angle. With the low price of panels these days it's a good solution. Get up on the roof and tilting panels and lowering them again can be a problem.

Frequently panels will degrade faster if they do not have cooling space under neath them. Check the warranty for your panel to see what the period is. Many framed panels have a 25 year warranty. Flexible panels may have a short warranty time.

[Winterbagoal]

I believe the Zamp flex panels are only warranted for 5 years. I could be wrong.

[AJMike]

My Winnie Fuse came with flexible SunPower panels and they are only warrantied for 5 years as well. Since they are flexible they are mounted directly on the roof so there is no air space under them.

I assume when they fail I will replace them with the rigid panels.

[Winterbagoal]

Originally Posted by AJMike

My Winnie Fuse came with flexible SunPower panels and they are only warrantied for 5 years as well. Since they are flexible they are mounted directly on the roof so there is no air space under them.

I assume when they fail I will replace them with the rigid panels.

X2. I may mount a new set of rigids/framed over the existing ones, and just move the cables. Undecided until it happens.

[SLOweather]

If you do a little experiment with a flashlight and a flat surface, you will see the problem. The amount of power/brightest light is when the light source (sun or flashlight) is perpendicular to the surface. As the light source becomes less perpendicular, the same amount of light is spread over a larger area.



You could search on 'noon solar insolation" to learn more.

[DavidM]

Sorry to be joining this discussion late. Solar output from a panel is dependent on:

The panel's rating (well duhhh!)
The temperature of the panel. Hotter is worse.
Fixed or variable and if fixed, the angle to the horizon- angle equals latitude gives best output.

Climate- Cloudy climates provide less sun than sunny ones (also duhhh!)
Lattitude- lower is better. Equator is best.
Time of year- June 20/ 21 is usually best because the sun is highest. December 20/21 is worst.

Chack out the following solar insolation maps which covers the latter three factors. Scroll down, the first is average, the second is June and the third is December. See:

https://www.solar-electric.com/learn...aps.html/#Map2

And FWIW I have installed three flexible panel systems on boats and RVs. None of them met rated output on a full sun day pointed perpendicular to the sun at midday. One a no name brand from Amazon was about 60% of rated output when new. And one lost more than 50% of its output after ten years (stored mostly in the garage). Needless to say, I don't think much of flexible solar panels.

David

[Winterbagoal]

The trade off of choosing flex versus solid framed panels, is weight. Many of the units that get flex panels these days are "OCCC weight challenged" to begin with units, that need all the "weight help" they can get. My 3 flex panels do a decent job, as is, and I'll deal with the rest of it, when/if it happens.

Just had the first real world trip using the 2 new Relion RB100-LT batteries and they have solved all the OEM factory issues, including the Norcold DC only fridge running all day/night.

[SLOweather]

Yeah, neither of our our "200 watt" Chinese flexible panels ever made even close to full output even during my preinstalation testing, and they both failed in lees than a year.

Re: weight... While I was shopping used panels at Santan.com, I checked the various weights and was surprised at the weigh differences for similar output panels. I finally opted for 2 250 watt "high efficiency" panels at 33 lbs each for $90 each, compared to regular 250 watt panels at $50 and 61 lbs each. The $40 difference was minimal when freight costs were added in.


Even in the low February afternoon sun, flat mounted on the Sunstar's roof, they were making 50% of rated power.



The flex panels weighed 7 lbs each, for a net weight gain of only 26 lbs each.