Solar Show and Tell

[AirMiles]

Here is the data file with the history graph.

[gregwall]

Originally Posted by AirMiles

Here is the data file with the history graph.

Great stuff! Thank you so much. I will be getting on the road June 18 - October 1, and I look forward to comparing and sharing our results.

Greg

[Bigventure]

So, let me ask you guys who have done it. With 4 100 watt panels and factory 10 gauge wire. Which would have the least losses. A 4 panel parallel group or a series/parallel group? One suffers from shading effects, one from wire size loss.

[sheriff1]

Bigventure, I think you will find opinions for and against both options. I’m about ready to put on the panels 4-100s myself. I was able to get heavier wire from the roof down to a place where I can pickup the factory 10ga and will have to use the last 8’ of the factory wiring as I’m not willing to run it exposed. I have a Victron 100-50 and am going to set up the wiring on the roof so it will be easy to switch from parallel to series/parallel. I think series/parallel will probably be best for me as I will generally be parked in unshaded areas when I will be depending on solar.

[pteck]

Originally Posted by Bigventure

So, let me ask you guys who have done it. With 4 100 watt panels and factory 10 gauge wire. Which would have the least losses. A 4 panel parallel group or a series/parallel group? One suffers from shading effects, one from wire size loss.

I'm on 4x 100w panels all parallel with the factory prewire.

Losses come in many forms. Efficiency losses at peak with low gauge wire, losses due to shade, greater shade losses due to series parallel dependencies, losses due to panel angle, losses due to panel type, controller type, battery type, cost/value losses.

It comes down to what one wants to optimize. There's no optimal for everything.

As a professional engineer engaged regularly in trade studies to make design decisions given requirements and constraints, my belief is to maximize solar production in challenging conditions. Properly sized, no one with solar is going to have production shortage in a "sunny day scenario".

[TouringDan]

Originally Posted by Bigventure

So, let me ask you guys who have done it. With 4 100 watt panels and factory 10 gauge wire. Which would have the least losses. A 4 panel parallel group or a series/parallel group? One suffers from shading effects, one from wire size loss.

I am facing the same decision regarding installing 4X100 panels on my bed cap. The distance to the controller is very short so the resistance losses are low. I believe I will go with all four panels parallel.

Dan

[HiHoAgRV]

We have just done 2 weeks with 1x Battleborn 100ah, 2x fixed 100w and a 100 w portable. All days except 1 we were fully charged by 10:00 . The slow day was mostly cloudy, snow and we started at 61% battery. We have a 12V domestic freezer set at 10 degrees running 24/7, watched tv/directv most nights for a couple hours. Partial shade mornings and evenings. I'm of the opinion that the portable 100 is just as effective as 2x 100 fixed if you are willing to move it a few times a day. Travel days the 200w fixed always charges to 100%.
My reason for the lithium was to absorb all of the solar available during the short time with no shading and I'm absolutely thrilled with the choice.
I did reprogram my charger to float at 14.3V since bulk was 14.4 plus 20 minutes resulted in a drop back to 13.3 before the lithium was at 100%
Peak observed rate was 249 watts
Super happy.

[AirMiles]

Here is the schematic for my 400W Series-Parallel configuration installation.

[AirMiles]

Originally Posted by Bigventure

So, let me ask you guys who have done it. With 4 100 watt panels and factory 10 gauge wire. Which would have the least losses. A 4 panel parallel group or a series/parallel group? One suffers from shading effects, one from wire size loss.

This question will be like watching gasoline being thrown on a fire.

I have 400W of solar with a series-parallel configuration installed on the 10 gauge factory pre-wire. I would not hesitate to do it in exactly this configuration again. It works perfectly in real life under all conditions. It is the most efficient method to get the most out of the 10 gauge pre-wire. This configuration is as efficient as running parallel on 4 gauge wire. It works better in low light conditions, such as dark and overcast days. It starts charging earlier in the morning and keeps charging later in the day. But as Pteck keeps saying, there is a trade off in that if one panel in the series pair gets significantly shaded, two panels of production can be lost versus one panel on a full parallel configuration. But in real life, shading of one panel has never been the factor that kept my batteries from being fully charged.

I’ve used this series-parallel configuration for 170 days over the past year. All but 30 days of my solar’s production has been posted in this thread for everyone to see. There have been only five days when I used my generator because I did not get enough solar production. All five of those days were when I was under a thick canopy of shade and dark rain clouds where it appears as if it’s dusk at noon. No solar configuration would charge the batteries under this lack of light condition. Look at my data that backs up opinions.

Here’s my last 28 days of production where I camped in tree-filled sites throughout the Blue Ridge Parkway. Look at how frequently my batteries floated - meaning they got completely charged. Tree shade did not stop my series-parallel configuration from keeping my batteries charged and this is why I prefer the most efficient series-parallel solar configuration.

[pteck]

Originally Posted by AirMiles

There have been only five days when I used my generator because I did not get enough solar production. All five of those days were when I was under a thick canopy of shade and dark rain clouds where it appears as if it’s dusk at noon.

Your data also speaks for the fact that optimization is best focused on the "rainy day scenario".

If one chases the 3% voltage loss optimization for a sunny day scenario, is this worth the significantly more loss of production on a shady, cloudy, or rainy day? Exactly the days that one will come up short?

I encourage everyone to do their own research. It's well understood and documented that series based setups are more impacted by shade and cloud.

http://www.youtube.com/watch?v=1qD3mN8VotQ

[AirMiles]

Originally Posted by pteck

Your data also speaks for the fact that optimization is best focused on the "rainy day scenario".

If one chases the 3% voltage loss optimization for a sunny day scenario, is this worth the significantly more loss of production on a shady, cloudy, or rainy day? Exactly the days that one will come up short?

I encourage everyone to do their own research. It's well understood and documented that series based setups are more impacted by shade and cloud.

That video is not research. That video is a ten second dramatization that exaggerates the effects. I’ve posted 170 days of data that shows that shading has not been an issue. My last 28 days posted a couple comments above show how well a series-parallel configuration works in some of the shadiest campgrounds in the east. Maybe some of you have been to some of these campgrounds: Lake Rauban Beach, Deep Creek, Mt Piscah, Crabtree Falls, Linville Falls, Julian Price, Doughton Park, Rocky Knob, Wompatuck State Park, Scusset Beach (sunny), Lamoine State Park. These are very tree filled campgrounds. Even the road, the Blue Ridge Parkway is not sunny. And even in these tree-filled locations, my batteries fully charged on 25 of 28 days. On the other three days, the solar produced enough AmpHours to allow the batteries to get through the next night without using a generator. I’ve only used my generator for charging on five occasions in my 170 nights of solar usage. That’s 3% of the time which Is acceptable for me.

I don’t know how an engineer could study this data and determine that the data does not support his hypothesis. He says to optimize for overcast days. That’s exactly what a series-parallel configuration does. It takes less brightness to achieve higher voltage in series-parallel. Therefore, it will provide more amphours on an overcast day than a full parallel configuration. It’s 9 am and completely overcast currently at the Airstream Terraport in JC where I am currently. Here is a screenshot of my current battery charging status. 5.8 Amps is not bad on an overcast day at 9 am.

Pteck and I are nearly in complete agreement. He makes valid points about the trade offs between series and parallel. But where we disagree is on how these trade offs effect real life production. My data shows series-parallel works perfectly in the real world. How can one explain my system performance over the past 170 cycles in locations all around the country in spring, summer, fall, and winter if shading is a big issue? Even in the video, the couple states that their motor home was configured in series and worked for them. A series-parallel configuration benefits from both the advantages of parallel and the advantages of series. I prefer the series-parallel configuration over both full parallel or full series configurations.

[pteck]

Airmiles,

With all due respect. I'm good with your position. It obviously works and works well. I don't expect anything to change your opinion of that and why should it. You have a great well setup system. [emoji106]

I could go much deeper with you on technical points but I suspect it wouldn't benefit anyone in this discussion other than to be contentious. My research is hardly based on the video, but it is succinct and enough for most.

I'm out camping this weekend too. My system works great charging 300Ah of battery, 200 lead acid and 100 lithium. I never fire my genny unless I'm driving my AC.

In everything, there's many possible and successful ways skin a cat.

Enjoy your system, it is a better system than most have. 400W is frankly overkill for most. I barely tap 20% of my reserve on most days.

[Philip Jones]

Can’t get enough of the education i am receiving in this thread. Fantastic for a new-to-solar guy.

I am going to install my solar in two steps, getting new batteries and converter first and then install panels and charge controller second.

AirMiles, if you were buying panels right now, who would you buy them from? AM Solar? I am looking to replicate what you have done exactly. I found your paper sketch of the wiring enormously helpful. Thank you!

[sheriff1]

Check out Renogy solar panels, they have sales once in a while and a quality product.

[Wconley]

I spent about a year looking into solar solutions and whether to install myself or have it installed. While not rocket science, I’m in awe of those that install themselves. I was just about ready to buy a setup from Renogy or AM Solar when we decided to buy a new trailer last year. With the new 2018 28 RBQ Serenity we decided to have an AM Solar setup installed for our winter trip. We were too late to get on Lew’s schedule in Hood River last fall so we had the system installed at AM Solar in Oregon and can’t say enough about their customer service. We had talked to our dealer about a solar installation but decided that for about the same money, we were getting better components overall. Plus, Airstream is pushing the ZAMP flexible panels which I’m not sold on yet even though they look so much better than the rigid panels. A friend of ours installed the flexible panels for exactly the opposite reason and I’m looking forward to seeing how they hold up after a couple of years.

We do a fair amount of off-grid and/or dry camping but our energy needs are relatively small with normal living stuff plus furnace (the big draw) and TV in the evening. With the exception of the AC/Heat Pumps and espresso maker, we wanted to live mostly as we would in a park. For this, the OEM inverter provides enough power. The unknown for us was solar energy in the winter southwest and how much solar would be needed to keep the battery topped up each day.

After my research and great gnashing of teeth, we decided to start with 400 watts on the roof (we can always add more) and a relatively modest 200 amp-hour LifeBlue lithium battery. Discussions with Airstream led me to not use the factory wiring as their stated limit is 300 watts and I wanted to keep all panels in parallel. It seems such a short-sighted waste that Airstream doesn’t supply bigger wiring but they probably hit the sweet spot of 80% of their customers. I know there’s a lot of discussion on this but to each their own. AM Solar spec’d all the Victron components and I went with their recommendations. In our discussions, all components, including the single LiFeBlue battery were mounted under the side couch so that there was no impact to our useable storage space. The sub-woofer that is mounted in this area got moved on top of the Victron 12/50 converter and simply held in place with substantial Velcro on the adjacent OEM Inverter. Everything fits well in this space and there doesn’t seem to be a heat issue. The Victron BMV-712 monitor is mounted in the upper cabinet above the kitchen counter so no holes were cut in the aluminum walls and we only look at it when we want to. With the Bluetooth capability, I almost never use the physical display.

So what about practical use? We just completed five months on the road from Seattle through the southwest, then across to Mississippi before turning north for a Kentucky Caravan and on up through Michigan UP and back to the Badlands, Yellowstone/Tetons and then home. We were gone from January 3rd to May 9th. We dry camped roughly half the time, especially the first three months when the weather was truly bad almost everywhere. Our experience was that unless in heavy shade trees (generally not a problem in the SW) or in dark, rainy clouds, the 400 watts on the roof will easily recharge the battery for our us by noon or so in the winter (by 7-8am in the toward the end of our trip when we weren't using the furnace as much!). It was a true joy to live at a comfortable temperature at night which dramatically reduces the humidity and sweat on the interior walls over the previous year of continual dampness. I can’t overstate this benefit of having better battery capacity! Of the times we were dry camping, we only needed the generator once after two days of cold rain in Snow Canyon State Park UT. There was very little solar energy and we really needed the furnace due to the cold temperatures which included freezing rain and snow. On the third day I topped up the batteries at dusk just to ensure we had enough to get through that night. I think there was a good chance the batteries could have provided enough power for us and the next day was sunny which would have easily recharged the batteries.

I’m very happy with the system we have and with choosing to have AM Solar do the install. I really didn’t want to be fussing with the system to get it to work and their attention to detail and a clean installation was impeccable. The only thing I might have done different would be to have installed a whole-house converter/inverter with higher capacity which would allow us to use our espresso machine and a hair dryer occasionally and having access to all the plugs for other stuff instead of just the plug by the door. The slippery slope is that at some point our 200 amp-hour battery wouldn’t have the capacity so everything is a trade off.

One surprise that I did get is that the current draw for the Victron converter is so much higher than the OEM Airstream converter that if it is in full charge mode, I can’t quite power it and my Easy Start equipped HP with our Honda 2000 generator. I’m still working through this but I believe this is the issue. When the converter goes to float mode, I have no problem.

[pcskier]

Great thread and I'll be reading the whole thing. Meanwhile, a couple quick questions. On my 23d, I am going to install 2 100w panels to start out, and have the charge controller that can handle up to 450w later if I add two more. With my miserly power usage, and being mostly in the southwest US with lots of sunny days, I think 200w will be enough to keep my batteries topped up so I can leave the genny at home most of the time. So my questions.

1. My trailer has "Solar Prewire." I gather that this means there is wire somewhere on the roof that would connect to the combiner, and then terminates down below near the electrical connections 'rat's nest' under my dinette. But I've read a lot of threads where many seem to route new wire down through the fridge area (on the 23d) to the rat's next. Is this because the factory prewire is deemed insufficient? Or is that dependent on wattage, i.e. 200 watts would be fine with the pre-wire, more panels/wattage needs bigger wire to be most efficient?

2. AM Solar has a kit with everything needed (except the Victron Monitor which is separate). The 2 panel "Zamp" system is $1250, and then an "Airstream" option which includes shorter and higher feet, to account for the curved roof on the Airstream. It also includes some sort of 'custom' wire/connectors on each panel. This option is $1395. I am trying to figure out what the big difference is for $145. When I posed that question, AM Solar emailed back: "Aside from the mount feet, the cable connecting the panels to the combiner box is different. The Zamp option uses the Zamp cable and connectors that came with the panel. The other option uses our custom 10/2 cable. Our option gives you a little more versatility and makes a much more durable connection."
Is it worth the extra $145 to get the wiring option that is described?

Thanks for input everybody, and again...great thread!

[pcskier]

Originally Posted by Wconley

I spent about a year looking into solar solutions...

Walt, great writeup, thank you!
You mentioned a 200 ah lithium battery. Dumb question, but I assume you added this and deleted the two flooded batteries? Or you were able to keep them and access that power somehow?
It sounds like you changed out your converter? Was that needed because of the lithium battery?
Thanks again!

[pteck]

Originally Posted by Philip Jones

Can’t get enough of the education i am receiving in this thread. Fantastic for a new-to-solar guy.

I am going to install my solar in two steps, getting new batteries and converter first and then install panels and charge controller second.

AirMiles, if you were buying panels right now, who would you buy them from? AM Solar? I am looking to replicate what you have done exactly. I found your paper sketch of the wiring enormously helpful. Thank you!

If I may suggest... The converter upgrade is wholly optional. Especially once one goes with significant solar.

I have had my convertor off for over a year and never use it. The solar controller is what does all the charging and tendering. It would be the odd day that I would need to charge with a genny and converter, for which the stock converter is fully capable.

Truthfully, I almost never plug in. Even at full hookups unless I want to run the AC. 400W solar is prodigious power.

[pcskier]

Originally Posted by pteck

I have had my convertor off for over a year and never use it. The solar controller is what does all the charging and tendering.

When you say "off", do you mean the breaker for the converter/charger is flipped off? Doesn't this cut off the 12V system even if not plugged in to shore power? Or when you just say 'off', do you mean you are never plugged in to shore power so the converter/charger is effectively 'off'?
I second the motion: very informative thread!

[pteck]

Originally Posted by pcskier

When you say "off", do you mean the breaker for the converter/charger is flipped off? Doesn't this cut off the 12V system even if not plugged in to shore power? Or when you just say 'off', do you mean you are never plugged in to shore power so the converter/charger is effectively 'off'?
I second the motion: very informative thread!

Depends how ones trailer is setup, but I believe most converters are powered off one of the 120v breakers. So turning that off unfortunately also turns off those branch outlets.

It doesn't impact anything in the 12v circuits as that is always powered by batt and solar.

I did add a custom switch to independently turn off the converter. Moreso because I added an automatic transfer switch to enable my inverters to power all 120v outlets and this prevents feedback to the converter charging the batts. Sorry if this may be confusing.

My opinion that there is an inordinate focus unecessarily placed on upgrading converters.