Winnebago Era Solar System Data

[Xisme2]

I recently purchased a 2022 Era 70A with 2 solar panels on the roof. There is no documentation from Winnebago as to whose they are or their output details, not even on the window sticker, even though they supposedly came from the factory, installed by the factory.

I believe them to be 100 Watt Zamp units. I would like to know their output voltage to the controller which is also a Zamp 450 W unit. The info being displayed on the controller doesn't make a lot of sense, but it may be some sort of abbreviation. The Zamp controller info brochure is not very detailed about what readings should be...somewhat understandably because the authors would have had no idea which or what panels it could have been hooked up to.

Anyone owning a similar unit who has figured out what panels Winnebago furnished, and what any specs may be, such as output voltage, I would very much like hearing from. Thanks!!

[HarryN]

Shouldn't be too difficult. Just use a volt meter to measure the voltage at the controller input terminals.

Roughly what kind of numbers are you seeing on the controller?

[Xisme2]

Harry, around 13.6 V all day, I suspect it's reading the battery voltage, not the panel output, which if they are Zamp should be around 15 to 18 V at peak sun. 1.2 amps, seems low, mid-afternoon, strong sun, I live in AZ. 2 100 watt panels connected.

[HarryN]

These are the most common zamp solar charge controllers. (on their web site)

Do any of them look like what you have ?

https://www.zampsolar.com/collection...ge-controllers

The manuals for them are here:

https://www.zampsolar.com/pages/knowledge

[TomF]

Originally Posted by Xisme2

Harry, around 13.6 V all day, I suspect it's reading the battery voltage, not the panel output, which if they are Zamp should be around 15 to 18 V at peak sun. 1.2 amps, seems low, mid-afternoon, strong sun, I live in AZ. 2 100 watt panels connected.

The output voltage of your panels will depend on how they are wired. When I upgraded from a single 130w panel to two 165w panels on my boat, I wired the panels in series so that I could reuse the old 10 gauge wire (higher voltage, less amps). My controller will handle a panel output of 12v to 50v.
When you say 1.2 amps seems low, what was the state of charge of your batteries? If they were in float, that would be normal.

[Xisme2]

Originally Posted by HarryN

These are the most common zamp solar charge controllers. (on their web site)

Do any of them look like what you have ?

https://www.zampsolar.com/collection...ge-controllers

The manuals for them are here:

https://www.zampsolar.com/pages/knowledge

Harry, THANKS for the URL's to Zamp's specs and manuals. Very helpful. I have the 30 amp 12/24 2 battery. I am concerned with the "amp" reading of 20. That is the battery amperage...they are fully charged...I would think they should be closer to 200 if it's reading both batteries.

[HarryN]

All of the solar charge controllers that I saw on Zamp's web site are PWM controllers. This means that they are designed so that in a typical 12 volt battery based system:
- The typical solar panel ~ 18 volts Vmp is correct
- The panels should be wired in parallel
- Current in = current out
- They are perfect for a wide range of lighting conditions, including on cloudy days.

In spite of the MPPT hype, for parallel panel wired setups, like most RVs, these PWM types will operate better under a much wider range of weather conditions.

I use a similar Bogart engineering PWM controller for 24 volt based power systems when the panels will be set up for 24 volt type panel arrangements. I tried to use the MPPT types but this really only works well when the panel Vmp is at least 10 volts higher than the battery charge voltage.

When the batteries are "fully charged", then the controllers shift to a sort of trickle charge mode, no matter how much sunshine there is.

It is sort of like having a glass of water that is full. There just isn't anywhere to put more water, unless some of it evaporates or is spilled.

[HarryN]

For measuring smaller currents like your solar charge controller, I use this clamp meter as a check.

380950: 80A Mini AC/DC Clamp Meter | Extech Instruments

For larger currents, I use this one. (actually the prior model of the same thing)

for higher currents, I have a 400 amp version.

If you are going to maintain an RV electrical system, you will need something similar or won't be able to tell what is really going on. It will save you a ton of time.

Don't get too carried away with perfectionism. It is a van, not a space shuttle.

[HarryN]

So - quick math for your system:

(amps) x (volts) = watts

(200 watts rated of solar panels working perfectly) / (13 volts at the battery) ~ 15 amps.

AZ / NM at high elevations in the winter time = panels are very efficient. Sometimes can even exceed their rating.

SF Bay area with more moisture in the air / some clouds, 200 watts of panels on a typical day are only producing ~ 75 - 100 watts at the same time of day. During fire season, this can drop to 20 watts. Yes really.

That is why you see such a wide range of suggested solar panel array sizes for the same vehicle. In this area, 200 watts is just a trickle charger. It takes 400 - 600 watts before it gets serious.

[HarryN]

If you have a volt meter or more correctly - digital multimeter, you can pull the controller off of the wall and directly measure the voltage at the controller terminals.

That is the easiest way.

In a PWM controller, the panel Vin will be essentially Vbattery. The reason is that the panel voltage is pulled down to the battery level.

[jakegw2]

I have two Zamp 170W panels wired in parallel. They put out 21.5V with no load, dropping to around 18.5V with a load.

I have two solar charge controllers installed with a selector switch to choose between them. The highest current reading I have seen from the Zamp controller was about 19A. This was in FL in July around noon on a cloudless day. That is around 350W from a 340W rated array, though only about 270W ended up going to the batteries (~80% of the available power).

I also have an EPEVER Triron MPPT controller. Since I installed it in the fall of last year I haven't been able to get a peak reading anywhere near the peak value from the Zamp yet, but when I compare them the MPPT controller produces sometimes as much as ~30% more current for the same conditions.

When summer comes I will try comparing them over a full day to get a better picture of the difference. My observations up to now is that while the MPPT controller produces more peak current the time it spends seeking the maximum power point can be significant in changing lighting conditions, during the seek process it often outputs a lower current then the PWM. The PWM controller by contrast produces it's peak current the instant it is engaged.

I think (or I would not have purchased and installed it) the MPPT controller will do at least 10% better over the course of a day, but I doubt it will be anywhere near the 30% you often see quoted when discussing MPPT vs PWM.

I personally think that for any camping conditions other than sitting in full unshaded sunlight the parallel wiring is probably better as it is less impacted by partial shading of a single panel. In full sunlight conditions series wiring would produce better results from the MPPT controller.