RV Solar Part II – The Equipment

So, following on from my gripping introduction to solar yesterday it’s time, with fanfare and fireworks (it IS almost New Year’s Eve after all), to reveal our choice of equipment. Every RV is different, so what we chose may not be right for your rig or your needs. Always, always take the time to figure out what’s right for you (true in life, love and general happiness, is it not?). So,  feel free to take our example as input, but definitely not as gospel :)

Going With 24V Panels

Our 100 Watt 24V Panels

I should start by saying that we decided to go with higher-voltage panels up-front and this, in turn, affected all our other equipment choices. The benefits of 24V panels are less loss through the system (using the water-hose analogy it’s like starting with a higher-pressure hose up-front) plus we liked the easier wiring and the current boosting capabilities it gave us (see below). It’s a slightly unusual choice and it is more costly. Most RVers choose 12V panels which require thicker wiring, but also give more open choice in controllers and panels. It’s a cost-benefit analysis and I would say you can get a solid solar system either way. In our case we’re geeks, and hubby had a decent year in the market so 24V was the way we decided to go…

Once we decided on 24V that immediately narrowed down our choice of vendors since not too many people offer a 24V panel that’ll fit comfortably on an RV roof. After much research we ended up going with a set of products from AM Solar, with an upgrade on wire-size and batteries. These guys only do RV solar (nothing else), have a good reputation, are all RVers themselves, are nice folks and above all were able to answer all our nit-picky questions. The final installation met our loss goals so we’re happy with the results. Here’s the full list:

1. 600Watts of 24Volt Solar Panels – We decided we wanted a pretty liberal power supply with 600 Watts of 24V panels, which led us in turn to 6 of the AM Solar RV100 series panels. We like the specs, warranty and format.
(Sept 2014 Update -> AM Solar has updated their line-up and now offer a  100W panel which is slightly shorter than the old RV100, plus some newer/niftier larger sizes. They no longer offer our exact 24V system, but all their panels are still “high voltage” so you’ll get the benefits. Check out their website for more info)

The Tristar Controller

2. Tristar MPPT 45 Controller (TS-MPPT-45) – Given our up-front choice for higher voltage panels, we needed a good controller that could handle the higher voltage input. MPPT controllers fit the bill and the Tristar 45 has good specs. It has all the charging profiles, including a custom setting, does temperature control and will actually sense and charge to the right voltage at the battery terminals using an external voltage sensor. This last feature is rather nifty since it makes sure you really get the right voltage exactly where you need it (= at the batteries) -> good stuff. Another nice feature of this controller is that if you generate more voltage than you need, it’ll convert that extra power into additional current going into your batteries (= a little boost for faster charging). Since we’re using higher voltage panels we should (hopefully) be able to take advantage of the boosting feature on a fairly regular basis.
(Sept 2014 Update – This is still a great controller and has worked perfectly for our 600 Watt system. However, if we were to do it over we would probably choose the bigger Tristar 60 so we have space to expand our system size in the future

3. AM Solar Tilt Mounts – We went ahead and chose the tilt mounts from AM Solar. We like the fact that they provide space under the panels and allow us to tilt when we need to.
(Sept 2014 Update – We love these mounts and would recommend them even if you decide to use a different company/installer. They make tilting super-easy)

4. Combiner Box – We decided to use a combiner box on the roof. So, each panel is wired individually on the roof, then they’re combined together in the box and a bigger wire goes from there to the controller. The bonus of this set-up is that you can use smaller wires on the roof, the wiring is easier/cleaner, plus you can easily add another panel down the line (if you ever need it).

Marine-grade wiring for the roof

4. Wire Upgrade – The standard system from AM Solar for the 24V panels use #10 marine-grade 90˚C wiring on the roof  and #8 wiring internally. Now, that may seem waaay too thin given what I wrote yesterday, but remember that 24V can run twice as long as 12V on the same wire for the same loss, plus we’re using a combiner box. We wanted to target ~2% voltage drop from panels to controller and ~1% drop from controller to batteries. So, we crunched the numbers using the wire tables I gave you yesterday and decided #10 was OK on the roof, but we needed to upgrade to the #6 wiring internally. That combo ended up working for the amount of wire we used in our install. For a home needing more wire you might need #8 externally and #4 internally and for a 12V system wired in series you might decide to use #4 everywhere -> it all depends on voltage, current and how far you’re running the wire. If I were doing this over for someone else I’d crunch the numbers specifically for their home.
(Sept 2014 Update -> AM Solar now offers #6,#4 and even #2 wiring for their systems and if we were to do it over we’d go with one of the bigger wire sizes, simply for the extra leeway. Bottom line is you can never go wrong w/ thicker wiring)

5. Lifeline AGM Batteries – We decided to upgrade our batteries to a bank of 4 Lifeline AGM 6V 220AH batteries (GPL-4CT). The AGMs will charge faster, and since they’re sealed there’s the bonus of no more maintenance. Lastly, since AGMs have really low internal resistance you can pile a lot more current into them -> that meshes nicely with the current boosting feature of our controller.
(Sept 2014 Update – Fabulous batteries! These have served us perfectly and we’d choose the same again)

Xantrex battery monitor

6. Xantrex LinkLITE Battery Monitor – This monitor hooks onto the batteries and tells you exactly how much power is either going either in or out of your battery bank. It’s definitely a geek-device and allows us to monitor exact usage from the batteries, something none of the other monitors we already have will do. If you’re just starting out on your solar quest and are looking for a device to tell you how much you’re using out in the boonies, this is the device that will do it for you.
(Sept 2014 Update – This is a great battery monitor and has served us well. We’d choose the same again)

Looking for another panel supplier? Here are some good, additional links on panel costs and suppliers around the US:

The final installation and measurement info comes next…..don’t go away…

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We LOooVE Comments, So Please Do

  1. Lauren Brown says

    Particularly enjoying your posts on tapping into solar for your energy. We have 24 panels on our roof and I even brought a foldable solar panel on my cross-country trip so I could keep my GPS, cell phone and computer charged up in remote areas where I was camping without access to electricity. Good luck with it. Will be interested to see how it turns out for you.

    Go Green! Lauren

    • libertatemamo says

      That’s right. I remember you using solar on the trip and I did think it was very cool at the time :) So far all looks good with the system but we’ve not really pushed it that hard. Can’t wait to see how it does on the trip out West. Hope you have a wonderful New Year! Nina

  2. Chris Adams says

    Hi Guys, is AM Solar using the Grape Solar panels? I noticed they are right next to each other and the Grape Solar part numbers are the same as AM Solar.

    I couldn’t locate the 24v panels on AM Solars website.

    We are designing out array right now and you can order the Grape Solar right at Costco for around $190 a panel but I can’t figure out if they are 12V or 24V.

    Any tips if you were to redesign your system right now? We are thinking 4 6V batteries, 400W to start with, the Tristar 60 Amp controller to keep it flexible for adding more later and 6 gauge cable.

    • libertatemamo says

      Hi Chris,

      AM Solar don’t offer our old exact 24V panels anymore. All their stuff is still “high voltage” but Voc is now around 21V. Anything higher than 12V will give you a boost, esp. if you pair it up with the MPPT controller.

      As for the Grape Solar vs. AM Solar the two panels are similar, but if you check the specs they are veeery slightly different. The Grape Solar 100 W is longer (47″ versus AM Solars 41″) and Amp output is slightly lower (5.4 vs AM Solar 5.7). If you don’t mind the added length on your roof the Grape Solar panels look good and can’t see any reason they wouldn’t work. Both panels are “high voltage”.

      As for what we’d do now if we did it over. Not much different except we’d go one bigger in wire size (#4 internally) and buy the Tristar 60 instead of the 45 so we had space to upgrade in the future. Going to #4 wire will also ensure you have the carrying capacity for a bigger current if you add more panels down the line. However our system has worked perfectly for two years and we’ve not felt limited in any way.


  3. says

    Hello……can you tell me what you have for inverter(s)? And are they modified sine wave or true sine wave?? We are putting a system bill of materials together and may want to upgrade our 2 – 10 year old inverters. Thanks.

    • libertatemamo says

      We currently have a Magnum 2000 modified sine wave. It’s OK, but it has managed to fry the microwave a few times. When we get the funds together we’re going to upgrade to a pure sine wave inverter. Much preferred.

  4. says

    Nina I have just completed my system. It is very similar to what you have. But I don’t seem to be getting the charging that I was expecting. I would like to know how many amp hours you been replacing at this time here in the south? At present we are in Yuma so the solar should be similar.

    • libertatemamo says

      Is your RV aligned east-west and are your panels tilted? The reason I ask is that the sun is very low this time of year and you’ll see massive (~40%) difference if you align and tilt your panels properly. This time of year, if tilted, we typically generate around 40-42 amps during bulk phase (the very 1st charging phase of the batteries). This is the only time you’ll see big currents coming from your solar since bulk is unlimited. When the system goes into absorption mode it becomes current **limited** so expect to see your volts slowly rise and your amps slowly go down, eventually dwindling to only a few amps. This is totally normal (it’s how the batteries charge) and this 2nd phase can take several hours. Once you’re in this phase don’t expect to see high currents unless you load the system (I.e. Turn on a bunch of stuff). If you turn on stuff you should see the solar responding again. Once you reach float (I.e. Your batteries are full) the volts will drop to float range and amps will be practically zero (again unless you turn on stuff). Make sense?

      Hope that helps. This time of year we usually charge fully by about noon.


  5. Pat H. says

    A question for you! I see you have installed a battery monitor in your solar power system. The experts all seem to agree that this is essential. Did you also install the remote digital meter for the Morningstar Charge Controller? I can’t find out (online) if the two meters are redundant or necessary. If I only need one the battery monitor looks like the obvious choice but I would like to know what conclusion you decided upon and your reasons for that decision.

    • libertatemamo says

      We have both and I feel it’s useful to have both. Let me explain.

      The Morningstar monitor shows you what’s being generated by the solar. So, it tells you everything that’s coming from your panels. This gives you an overview of your amps generated, your total watts…etc. This is how we know we generate almost 40% more amps when our panels are tilted, for example. Plus it sure is fun to watch those amps rise in the morning.

      The battery monitor is the other side of that story. It monitors everything going in and out of the batteries. So, it gives you a great overview of the state of your batteries, but doesn’t really tell you what us going on at the panels…just what your voltage is and weather you’re drawing positive, negative or full/flat. Also the monitor can get out of synch sometimes and needs to be reset. It’s a superb piece of equipment for monitoring power draws and such though.

      You can certainly make do with just the battery monitor, but it sure is nice to see both.


      • Pat H. says

        Thank you for the explanation re: the reason for both meters/monitors. It makes perfect sense that in order to fully utilize the MPPT function of the Morningstar charge controller one must first maximize the output of the solar panels and the charge controller meter is the only true way to achieve this. We have a 38′ Endeavor which has similar roof space as your rig. Given that the cost per watt output is generally less with larger panels what was your reasoning for choosing 6 100W panels instead of fewer higher watt panels? Also, may I assume that you have your 24V panels wired in parallel? Why did you choose 24V panels (more expensive) instead of wiring pairs of 12V (less expensive) panels in series which would achieve the same higher voltage to the charge controller?
        Thank you for allowing me to pick your brain. The puzzle of solar power is indeed fraught with conflicting opinions/applications and I respect the level of research put into your decision making and your erudite explanations. Merry Christmas to you!

        • libertatemamo says

          We went with the 100 W panels from AM Solar because they were narrower than regular panels. So, they were easier to place/tilt on the roof & avoid shade problems. We just liked the form factor. No reason you can’t go with wider panels though. You just need to think more carefully about your placement.

          As for the 24V. It makes for more efficient wiring (less lossy + you can use thinner wires from the roof) plus the higher voltage allows you to take full advantage of the MPPT boost (which is quite nice).


  6. Pat H. says

    A question about your solar panel mounting. Did you bolt them down or did you use adhesive mounts (sticky feet)? I would like to use the adhesive mounts to avoid 16 holes in the roof but am having difficulty convincing the installer that they work. As you know, some people are averse to embracing newer technology.
    Pat H.

    • libertatemamo says

      We used adhesive mounts and have had no problems at all. I highly recommend them.


      • Pat H. says

        I thought you did. You should have seen the look on the installer’s face when I showed him the “sticky feet”! Total luddite disbelief.

      • Mark Borseth says

        Hi Nina, will be heading to AMsolar next week but have not heard about “sticky feet” until seeing your post. Does AMsolar offer these or offer as an option? If not where would I find them?



        • libertatemamo says

          It’s the special 3M mounting tape. AM Solar will be able to tell you all about it. Don’t know if they carry it I stock, but I’d be surprised if they didn’t. They use it on practically all their installations.


  7. Steve says

    Nina and Paul,
    We are at AM Solar in Springfield and Marvin is running our project. We decided to start with “just” six 135W panels (810W) 6 lifeline 6V Batteries and the Magnum2800W inverter. We also went with the Tristar 60 controller. Possible regret will be not going for 2 more 135W panels!

    Thanks for years of postings and all the data you provide.
    Steve …. X- CY

    • libertatemamo says

      Oh sweeeeeeeet! Sounds like a fabulous system. So happy you got Marvin to set it up too.


  8. Jim Mellema says

    wondering hard about the AGM battery (myth)?

    Can charge at higher current?
    Our magnum 2012 runs a max of 106 amps into our 4 new conventional lead acid batteries…

    Solar is in our near future. But the batteries were just replaced…

    Is the charging current you speak of a limit of solar, or what?
    There is not a solar system on God’s green earth that can charge at a hundred amps….

    ‘fraid I don’t fully understand this…

    • libertatemamo says

      AGMs have less internal resistance so you can push more current in with less loss (= less waste). This means faster overall charging regardless of current levels. We only see 100+ amps going in when we’re running the generator. On solar we never deliver that much (~40 amps is our max.). But either way, our batteries charge faster because we lose less of the charge to internal resistance/heat. We definitely noticed this when we first moved from conventional lead acid to AGM.

      Hope that helps to explain it.


  9. Ed Soniat says

    I am looking at AMSolar based upon you recommendation but as I price shop they seem to be very expensive. They charge $450 for the tristar 45 mppt charge controller and it is available for $168 on Amazon. I prices one of their solar panels and found that S-GO160 which they sell for $429 in a kit with some wire and brackets. It looks just like the Grape Solar GS-S-Fab160 that sells for $229 add $50 tops for the brackets and wire and you are no where near $429. Is there any explanation for these mark ups?

    • libertatemamo says

      The controller you saw on Amazon for $168 is the TS45 not the TS-MPPT-45 which is also on Amazon for $442. The MPPT function is the big difference and why there’s a price premium on it. We’ve had a lot of use out of our MPPT, and it’s the only one they sell here at AM Solar. As for the panels, I’d ask AM Solar about the details. they’re very open to talking about equipment, even if it isn’t theirs.


      • Ed Soniat says

        Thank you for pointing out my error. I’d like to go with a well regarded organization like AMSolar but I have to verify the value. Knowing that they aren’t marking up the charge controller is important. I have already written one of their installers about the other items and prices. We are looking at an install north of $10K and that means it is really worth while trying to get informed.

        • libertatemamo says

          Oh I totally understand! We spent months researching before we finally decided on AM Solar and I recommend everyone else to do the same. It’s a major $$ decision.


  10. lewster says



    Just ask Ed Soniat how often he gets 100 amps of charge from his solar array into his batteries. It is not only possible, but happens on a regular basis.


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