Adding two more Zamp solar panels to the roof

[Dennis C]

Hello everyone. I'm hoping to get some information or thoughts on adding additional solar panels to the roof of my International Serenity 23FB. I've currently got an aftermarket Zamp system that was installed by my dealer when I purchased my Airstream in 2020. It has two Zamp 90W panels, a Zamp solar controller in the galley, and two AGM batteries. It has generally worked well, but I'd like to add more solar capability and at some point in the future I'd like to upgrade to LiFePo batteries. I'm planning to add one or perhaps two additional 90W panels to the roof.

My Zamp controller has the capability to manage additional panels. I have a couple of questions for the solar experts on the installation. My Airstream goes into my local dealer for service in the next couple of months, and I am planning to have them install the additional panel(s). Here are my questions:

• Is there anyone here with experience putting four panels on the roof of a 23FB? Will two additional panels fit? It looks to me like there's plenty of room.
• My existing panels are plugged directly into the connector on the roof of my Airstream. Will the new panels plug directly into the port? Will it accommodate two more panels? I thought I saw somewhere that the factory connector only has three ports, meaning I could only add one additional panel.
• Is the factory pre-wiring adequate for additional panels, or does it need to be upgraded to larger gauge wire?
• What should I ask and/or confirm with the dealer prior to the installation?

Thanks to all the solar experts for your comments and thoughts.

[GOUSC]

Hi Dennis,

I'm not an expert but was in a situation similar to yours. I'll tell you what I did and let the experts chime in.

My 27' Globetrotter had the factory solar option added when I bought it. 2, Zamp 80W solar on the roof and 2 Lifeline AGM 80Ah batteries. I had also read that the port on the roof only had an input for 3 panels. I added 1, Zamp 90W panel on the roof to give me 250W of solar on the roof. I think you can add more panels but you have to wire them in series vs parallel and that is above my skill level.

I then called AM Solar to consult with them about changing my Solar controller to an MPPT Controller. They suggested the Victron MPPT 100/30 controller. They also suggested added a breaker and a solar disconnect. I followed their instructions online for how to connect.

This was the most important change I made as this controller is more efficient that the non-MPPT controller installed by the factory. Your 2020 may have this controller already. If it doesn't, I would suggest it.

Later, I consulted AM Solar on portable panels as a supplement. They suggested 2, 100W Zamp Obsidian portable panels. 1 of them has the solar controller and the other doesn't. They connect together to provide an additonal 200W of solar. I just plug these directly into the Zamp plug outside the battery box.

For my uses, I don't even need to use the portables if I have good sunlight. I do not camp in the winter if I can avoid it. I got the portables for those times when I need to find the sun. Other uses may require more, or less, solar.

This gives me 450W of solar if I need it. The factory wiring was 8 gauge and I just used 8 gauge throughout all connections from the roof to the DC distribution box. When my AGM's crap out I will probably switch to 2 100 AH Battleborn lithiums.

[Dennis C]

Thanks for sharing your experience. I appreciate that. Most of our camping is done in the mountains, so we have very little need for air conditioning. We generally don't watch television or use the microwave when camping, so solar is a good option. I really just want to add some capacity. I think that even if I add one more panel and increase my rooftop solar to 270W, that will be pretty good for most of our needs. If we think we are going to need more power, then I bring my generator along.

[vanderwielen]

Your port on the top of your unit which accepts solar wiring is most likely has 3 inputs. I just installed 4 - 90s on the top of a 20FB and simply used a Y connector for 2 of the panels. The factory wiring was 10 gauge, which is adequate for the VOC of about 18v producing 15 amps (ish). You won't have any issues. Verify that your Zamp controllers an MPPT type, not PWM. In fact, I'd consider upgrading to a Victron Smart MPPT.

[Dennis C]

Thanks. Is the Y-adapter something you got from Zamp, or did you get it somewhere else?

[jeffb831]

Here is the Zamp link: https://www.zampsolar.com/products/p...-sae-y-adapter

[vanderwielen]

Originally Posted by Dennis C

Thanks. Is the Y-adapter something you got from Zamp, or did you get it somewhere else?

I installed legacy Zamp 90s. They come with a solar SAE connector. I simply bought a Y on amazon.

Verify your polarity before using:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[field & stream]

Not an expert, but some similar experience. For a few years we had a 23’ with 200w of rooftop solar and two 6v T105 batteries. Camped year round in the Rockies and the Pacific coast with zero power issues. We had an absorption fridge, not electric only.

If you have an absorption fridge, then I think with one more panel you will be fine and with the addition of lithium batteries you would be approaching certainty. If you have a compressor fridge, then I would suggest you do the extra panel and the lithium upgrade to give you the storage to get you through low solar circumstances.

[Dennis C]

I've got the old-school absorption fridge. When we're off the grid, we use propane for the fridge and the water heater, and we do all of our cooking outside, on the gas stovetop or in the gas oven. The 180W of solar that I have now works fine for a couple of days, but if I'm at a shady site or it's cloudy outside, then I'm sometimes lacking a bit. I realize this would impact additional panels also.

[panamerican]

Originally Posted by field & stream

Not an expert, but some similar experience. For a few years we had a 23’ with 200w of rooftop solar and two 6v T105 batteries. Camped year round in the Rockies and the Pacific coast with zero power issues. We had an absorption fridge, not electric only.

If you have an absorption fridge, then I think with one more panel you will be fine and with the addition of lithium batteries you would be approaching certainty. If you have a compressor fridge, then I would suggest you do the extra panel and the lithium upgrade to give you the storage to get you through low solar circumstances.

It's been suggested here by a number of folks that if you have the 12v compressor fridge, that you really need 400 watts of solar at a bare min and a min of 200AH of lithium batteries. With some shade days and some sun days, you could extend that time between running a generator to 405 days, maybe. The real variable is how much sun you'll be able to capture....also realized that the panels themselves, as they age lose generating capacity.

[1StreamDream]

I think more capacity will definitely give you more flexibility, and I did a very similar thing. I now have a total of 480w on the roof of my 25' RBT, but I have to say I think the most valuable way for you to add capacity is to add via portable solar panels, unless you have some reason to know in advance that you will always park in clear sites with full sun. We like the shade, and most times, that impacts how much the panels on the roof can collect. Portable panels as an addition helps ensure you will always be able to align them with optimal sun exposure, just something for you to keep in mind as you contemplate your expansion. I have an older Zamp portable suitcase arrangement (140w) with its own dedicated controller, and I added a 10' extension cord set to it so I can have a wider range of placement options.

[Dennis C]

Originally Posted by jeffb831

Here is the Zamp link: https://www.zampsolar.com/products/p...-sae-y-adapter

Thanks for that. So if I use this splitter for two panels, will my Zamp solar controller show that I have three panels connected (two 90W and one 180W)?

[jeffb831]

Originally Posted by Dennis C

Thanks for that. So if I use this splitter for two panels, will my Zamp solar controller show that I have three panels connected (two 90W and one 180W)?

I am not familiar with the Zamp controller but most solar controllers don't show the status of the individual panels.

The panels usually connect to a combiner on the roof which combines the electrical flow from each panel into a single set of wires, and then the charge flows to the controller. The controller has no way to know which panel the voltage came from.

[Dennis C]

The Zamp control panel has an LCD graphic that shows how many panels are connected. I'm not sure if it serves any meaningful purpose other than letting you know that the panel is functional.

[jeffb831]

Interesting.

I wonder how it communicates to the panels to know how many are present and is able to differentiate between 2x100W panels vs 1x200W panel.

[tjdonahoe]

13 31’ Classic. Has a 10 gauge pre wire…installed am solar c box…2 90 watt zamp obsidian panels..used 3 m tape and silkflex caulking …3/100 victron controller…using my phone as a meter..if this works out..this fall I will install a couple more obsidian .panels..giving me 360 watts…

[tjdonahoe]

Originally Posted by jeffb831

Interesting.

I wonder how it communicates to the panels to know how many are present and is able to differentiate between 2x100W panels vs 1x200W panel.

The panel is the boss…it knows what it is producing…and sends it down the line…

[jeffb831]

Originally Posted by tjdonahoe

The panel is the boss…it knows what it is producing…and sends it down the line…

But in this case the "line" is a power line, not a communications line.

How does the controller get told that 5 amps came from panel 1 and 5 amps came from panel 2 when the combiner aggregates them into 10 amps being sent down the line? Or just a single panel sending 10 amps down the line?

Is there a communication protocol involved, similar to POE, that allows the panels to communicate with the controller?

[uncle_bob]

Originally Posted by jeffb831

But in this case the "line" is a power line, not a communications line.

How does the controller get told that 5 amps came from panel 1 and 5 amps came from panel 2 when the combiner aggregates them into 10 amps being sent down the line? Or just a single panel sending 10 amps down the line?

Is there a communication protocol involved, similar to POE, that allows the panels to communicate with the controller?

Hi

When you have all the panels on the roof, they wire up (in series or parallel). There are only two wires coming into the controller. It sees a "blob" of unknown dimensions and deals with it. A MPPT controller searches back and forth to automatically find (and adapt to) the maximum power point. As conditions change, so does the point. That's why it needs to constantly search for the max. What it found 5 minutes ago may not be correct right now.

Bob

[jeffb831]

Originally Posted by uncle_bob

Hi

When you have all the panels on the roof, they wire up (in series or parallel). There are only two wires coming into the controller. It sees a "blob" of unknown dimensions and deals with it. A MPPT controller searches back and forth to automatically find (and adapt to) the maximum power point. As conditions change, so does the point. That's why it needs to constantly search for the max. What it found 5 minutes ago may not be correct right now.

Bob

My point exactly. The OP stated that the controller is able to count the number of panels on the roof and display that number. I am questioning the technology that is being used to determine that information when all the controller sees is a "blob" of voltage.