Solar expansion

[Gr63]

Just taken delivery of 2022 View 24D. Have found installed 2x100W Zamp panels inadequate for dry camping needs and looking to install 200W more. The zamp port on roof is only 3 port and 2 are taken by current setup. Can I add 2 more obsidian 100W panels and have them connect to the remaining roof port via a Y cable?

[DavidM]

The OEM solar wiring is probably #10 gauge wire. If you wire your two new panels in parallel with the old, then you will have as much as 400/12=33 amps on the wiring from the port to the solar controller. Even if it is a 30A Go Power controller which may work the wiring, it will have over 1 volt of drop due to the length and wire gauge. So...

Wire the two new panels in series and then you can get their output into the port through the third opening. Then open up the port and rewire the two existing panels in series. Then wire the two existing with the two new in parallel. That will significantly reduce the voltage drop.

But, you will have to replace the existing controller, assuming it is a PWM type with an MPPT type. A Renogy 40A Rover should work great. See https://www.amazon.com/Renogy-Charge...s%2C980&sr=8-3

David

[macnut]

I have a similar setup, and I’m using all three ports on the roof. However, Winnebago also provided a port in my electrical bay for a removable solar panel. This allows for 4 panels at the same time, with 3 on the roof and one on the ground. Just a thought to avoid rewiring costs. Regardless, best of luck on your solar expansion.

[creativepart]

You can use 400w of panels and to do so you can use the Y-cable you mention. That's not the absolute max but is getting close to it.

Changing to an MPPT controller as DavidM suggested would help BUT, in the View the Zamp 30amp controller and it's read out is on central display on your interior wall and replacing it with a MPPT controller would alter the interior look of your system and remove the display - which is an important part of your overall charging system.

I replaced the Zamp PWM controller with the Victron Smart Solar controller and I'm very pleased with the result. However, my OEM Zamp controller was in a basement cabinet not on prominent display in my RV's living quarters.

[Gr63]

Thanks DavidM. Both pairs in series and then parallel makes sense. Could I just replace the 30A controller with the Zamp 40A?

[Gr63]

Thanks macnut. This sounds like the simplest solution and maybe most desirable as I’ll get flexibility with the portable. Is there a max wattage that I can put through that external port. Was thinking of getting the baldr folding. Figured with cable extensions and reverse polarity jacks I’d be lucky to get 90-95 watts out of that.

[Gr63]

Also is the extra port near the wet bay direct to the batteries and therefore requires a controller or managed by my existing Zamp 30A

[creativepart]

The external port should be (I expect it is) wired directly to the Zamp 30-amp controller.

The max solar wattage with the roof and external combined is approx 400w. Actually, you can push that a little but don't exceed 500w. Everything is sized for 30-amps and going over 500w would exceed that amperage.

Zamp doesn't make a 40-amp controller. Just the 30-amp. Other than the reason I explained above about the interior esthetics - if you were to upgrade controllers I'd go with Victron and get a MPPT controller. The Zamp is PWM and not as efficient.

One alternative is to add a 2nd controller - say for the external port OR get a portable solar panel with a built in controller and change the wiring for the external port to go directly to the batteries.

That would be quite easy to do - right now you have 10ga wiring from the roof to your controller and a second set of 10ga wires from the external port to the back of the controller. It would be as easy as relocating the external port's wiring from the controller's roof solar input to the battery output side of the controller. Easy Peasy.

[CoastalEd]

So many in this thread want to complicate things. Not necessary in this case. Keep It Simple, Sir. Just use a Y cable and connect your two new 100 W panels to the remaining solar port on your roof combiner. This per Zamp, their 30A charge controller can handle up to 510 Watts.

[creativepart]

Originally Posted by CoastalEd

This per Zamp, their 30A charge controller can handle up to 510 Watts.

Except not all of the 3-port Inputs on the roof are good for 500w. If you look at the top of the Portal some have 500w stamped into them and some have 400w showing on the port.

Here's a photo showing the 500w model:

[Gr63]

Thanks to everyone for your input which has helped me frame my questions to Zamp and winnebago. I’ve opted for the simple solution. 2X100W Zamp obsidian panels connected into the remaining input on the roof cap via an SAE to SAE Y cable. Existing and new will be in parallel. Max input is 510W for the Zamp 30A controller (they do make a 40A controller that has the exact same dimensions as the 30A so if I want to upgrade it’s a simple switch out to the 40A) I will see how this set up goes and also considering portable folding panel for more flexibility after I get this installed. Just looking at using the double sided VHB tape for roof bond - looks like that will work without needing to drill holes.

[creativepart]

Originally Posted by Gr63

Max input is 510W for the Zamp 30A controller (they do make a 40A controller that has the exact same dimensions as the 30A so if I want to upgrade it’s a simple switch out to the 40A)

So sorry I commented erroneously. For years they had the 30-amp and smaller controllers. But I was not aware of the 40-amp. I should have checked before saying they didn't have one.

Apologies.

[macnut]

Sounds like a good plan! Let us know how it works out and if you need to upgrade the controller.

[CaptainMitch]

I too have a Winnebago View, with 400watts of solar, 450 amp hours of lithium batteries, a 2,000 watt continuous inverter/charger, Victron MPPT solar controller, dc/dc charger, etc..
In my opinion, the panels should be set up with all inputs having voltages that are similar. To gain the longest charge times, you will want to run pairs of panels in series, thus having two power inputs into your controller, each operating at roughly double to individual panel output voltages. Keep in mind that most 100W panels have an output voltage of 20+ volts, so this can be 40-50 volts per input. You should also use an MPPT controller so the voltage is matched to the batteries, avoiding battery or controller damage.
Smart MPPT controllers, and in my opinion you definitely need an MPPT controller, typically do not start charging until they reach about 5vdc above the current battery voltage, due to the power loss necessary for the controller itself to operate (it is not 100% or deficient). Thus, having panels paired in series will effectively double the input voltage, greatly increasing the hours of charging you will attain eqch day (starts charging earlier and charges later).
We experimented with 4 panels all in parallel and 2x2 in series, and roughly speaking, nearly doubled to he number of charging hours each day running pairs of panels in series..
If you would like a copy of my wiring diagrams or have other questions, please feel free to reach out.

[Seron]

Not being an electrical engineer, I'm overwhelmed by all of the electrical acronyms associated with designing a solar panel array. Can anyone provide a definition for all of these acronyms and make it understandable for the layman? Is there a dictionary for them? Thanks in advance!

[CaptainMitch]

A little translation

VDC: Volts dc

MPPT: When comparing an MPPT (Maximum Power Point Trackers) controller to a standard PWM solar controller, MPPT controllers convert output voltage to an appropriate maximum voltage and current for the batteries selected in a constantly monitored and efficient manner, thereby greatly improving efficiency as compared to simpler PWM controllers. MPPT controllers work to provide batteries with the proper power for all battery conditions (roughly). MPPT is recommender for all applications where regular input voltage exceeds that of batteries or more than two solar panels are used. MPPT controllers are up to 30% more efficient than PWM controller.

PWM: A simple, cost effective solar controller for limited applications, using Pulse Width Modulation to control output by rapidly switching on and off power supplied. Not recommended for high efficiency applications, more than two solar panels, or complex and large battery arrays (Lithium, etc).

In Series: connecting two or more roughly matched power sources (batteries, or in this case solar panels) in a linear manner (from positive of 1st source, to negative of second source, then positive of second source, etc), thereby creating voltage equivalent to combined voltage of power sources, while keeping amps consistent.

Parallel: All negatives of power sources are connected together and all positive of power sources are connected together (separate from negatives/ground). Keeps voltage unchanged while increasing amperage. For battery powered equipment,, it does not increase power to equipment, but lengthens power supply time.

Inverter: I’m this discussion, it refers to the conversion of A/C power to 12vdc.

DC-to-DC charger: Isolates two battery systems, such as engine start battery and house batteries. Can also increase or decrease charging supply voltage to match battery requirements. I example: : helps to avoid overcharging of standard batteries when otherwise in same circuit as higher voltage lithium batteries, or risks associated with burning out alternators.

AGM or standard lead-acid versus Lithium batteries in simplest terms: AGM and lead acid are excellent at supplying rapid, high amperage output, for things such as starting engines. However, lead acid batteries are only useable for about 50% of their rated amps. AGM are long lasting and work well even in cold weather (let’s say below freezing) and are better than lead-acid at long power draws, as well as generally having a good life-cycle.
Lithium batteries have the ability to store significant energy in small, light batteries, often less than half the weight of similar AGM batteries for similar amperage. But lithium batteries can be discharged in useable voltage down to 10-20% of their full capacity, thus providing far more/longer energy supply at the same amperage, and at significantly less space and weight. However, lithium batteries can suffer damage if used when the cells are in extreme cold, and lithium is not good for rapid discharge, such as starting of large engines.
In short, lead-acid and AGM is good for engine c making, and lithiums are good for most applications for house batteries.

I hope this helps.

[DavidM]

Originally Posted by Gr63

Thanks to everyone for your input which has helped me frame my questions to Zamp and winnebago. I’ve opted for the simple solution. 2X100W Zamp obsidian panels connected into the remaining input on the roof cap via an SAE to SAE Y cable. Existing and new will be in parallel. Max input is 510W for the Zamp 30A controller (they do make a 40A controller that has the exact same dimensions as the 30A so if I want to upgrade it’s a simple switch out to the 40A) I will see how this set up goes and also considering portable folding panel for more flexibility after I get this installed. Just looking at using the double sided VHB tape for roof bond - looks like that will work without needing to drill holes.

If all of the panels are connected in parallel the maximum amperage is about 400/12= 33 amps. If the cable to the solar controller is #10 gauge and I bet it is, then if you have a 20' run to the controller, the voltage drop will be 1.4 volts. More than 10% of your power from the panels will be lost. Also at some point, maybe 2-3 volts of drop, the controller won't work as its input voltage is too low.

Yours should work, but you are wasting 10% on voltage drop and another 10-15% on the inherent inefficiencies of PWM controllers vs MPPTs. So it is like dedicating one of your four panels to cover these losses.

Wiring the four panels in series/parallel reduces the voltage drop significantly and with a MPPT controller (required for series/parallel wiring) your losses including voltage drop and controller inefficiencies should be less than 10% rather than 25+%.

It doesn't cost you any more to wire them in series/paralle and the only additional cost is the MPPT controller. A Renogy 40A Rover MPPT controller costs $140.

David

[Seron]

Thank you, CaptainMitch! This will be a great help. I now have starting point to begin to get an understanding of how batteries, solar panels etc. relate to each other.

Seron

[CaptainMitch]

Do yourself and your wallet a favor. DON’T use two sided tape. Use Eternabond. Put it in the leading edge, then a pi ce about 6” long on boat back corners as well as the middle of each side. Roll the tape down well and it will stay in all conditions.
Also, solar panels put out a lot of heat. A cheap sheet of plastic corrugated board that you can get from Home Depot, cut to fit below the panels, will provide air flow and lower the roof temperature.
Good luck!

[eyecando]

I think you will find out you will never get close to 100 watts out of a 100 watt solar panel in actual use.

There are several things preventing you from getting maximum power out of one of these panels.

First of all with a PWM controller, unless your batteries are very discharged, you are going to need something over 13.2 volts to charge them and more as they charge up and the voltage increases. So you can see that 100 watts / 13.2 volts = 7.5 amps. But if you look at the short circuit current for the panel, I believe it will be somewhere near 6 amps depending on the model and manufacturer so you can expect less than that number.

An MPPT controller will help, but still don't expect to get 100 watts out per panel. The actual current will depend to a large extent on the state of charge of the battery and it's internal impedance. Lead Acid batteries will have the largest impedance.

I have two different systems installed both with 4 100 watt panels.
My trailer has an MPPT Victron controller with the batteries connected in a series parallel system with 2 100AH AGM batteries in parallel.

My Navion has 4 100 watt panels with a PWM controller with a 200 AH Lithium Iron Phosphate battery and the solar cells all connected in parallel. I used a Y connector for one of the ports. I would like to change it out to a MPPT controller, but don't want to do away with the installed meter. I'm not convinced that I would see a large change in the maximum charging current anyway, but eventually I'll probably make the switch. Obviously, there are advantages with the MPPT controller.

AGM and other lead acid batteries charge slowly where lithium iron phosphate batteries will take a charge must faster due their low impedance.

Unfortunately, I don't have maximum charge rates for my systems since I don't routinely run them down and then have sufficient sun available at that time.

Mike