Any tips on my setup?

[ewarnerusa]

Fancy schmancy, Wrybread. I tried googling Raspberry Pi and don't exactly have it figured out. But it looks like some type of controller for turning USB ports on and off based on a user program? Anyway, if you're monitoring things by computer then you can hook up a Morningstar Tristar to a PC as well and use the MSVIEW software to access/monitor everything the $100+ remote panel offers. I suspect much more actually, but I don't have the remote panel with my Tristar (PWM 45) to compare. MSVIEW makes programming and monitoring the Tristar very easy. I have geeked out over program setpoints plenty of times and monitored things closely with the laptop running MSVIEW, but now I just look at my digital voltmeter to know what charge stage things are in to have a feel for what is going on. Bottom line, we don't run out of battery power while camping and (for us) no need to know any more details. Who says solar doesn't work for off grid camping, right?

[Wrybread]

Well that's interesting, I called the folks at the link Sunking posted for the Morningstar TS-MPPT-45 asking why their price is a good $100 cheaper than everyone else since I figured it must be grey market, and they said that they'll be increasing it by the end of the week to match Morningstar's MAP ("minimum advertized pricing") policy. So if you're in the market for that charge controller, you might want to grab it from that link asap! Or maybe they'll honor that price ($336) in the future if you ask.

As far as the update on my project, I connected a Raspberry Pi to my controller using the cable method here and wrote a little Python script that switches my fridge over to AC power whenever the battery's SOC is above 85% and the charge controller is putting out more than 300 watts. I'm not sure how the Tracer computes the SOC, but it doesn't seem to be only based on voltage, and so far its been a useful metric for determining when the batteries are charged well enough to power the fridge. I might change the threshholds of course, but so far so good, and at the end of the day I get a few hours of solar fridge time and fully charged batteries. I've only tested for a few days so far though, and I'm not yet logging how much time per day I'm getting of AC fridge.

My fridge (standard RV style Dometic) pulls around 280 watts when on AC, so I'd prefer not to power off batteries unless they're actively getting charged. Incidentally this is a very easy thing to do with any fridge that has an "auto" mode, since when they receive AC power they'll use it, and when the AC power is removed they kick back over to propane. So all the Pi or whatever simply needs to trip a relay when the threshhold is met.

From there it was easy to make a little app so I can monitor my panel remotely. Here's a screenshot of what it looks like in the morning with the sun coming up. The value in the center and on the graph is wattage. I plan to add the rest of the relevant data from the charge controller (pv voltage, pv amperage, battery SOC - to whatever extent that's useful) and the temperature inside the fridge and its power source at some point. IMG_2113.PNG


Some of the other values given by the charge controller over the modbus interface are kind of interesting too, like maximum pv voltage today, generated energy today / this month / this year / ever. The full list of parameters is here if anyone else needs them.

I need to watch how things work over the course of a couple of weeks, since obviously I don't want to use this system if it means my batteries aren't getting charged, but that should be solvable by adding the third panel or changing the threshholds.

[Wrybread]

I don't park my RV in the shade, but I do store surfboards on the roof of my camper that occasionally cover part of one of the panels.

And as far as the charge controller, that is indeed a good price and I bow before the god of shopping. That's oddly cheap and doesn't show up in a google search or on google shopping, typically it's more like this or this or this. But it's still more than twice the price of a unit that has served me perfectly well, and that's before adding an additional $140 for the remote monitor, which is important for my setup.

EDIT: the price at that link has been fixed, and is now $478.

[Sunking]

I cannot wire my panels in series because of shade issues.

Now that is some funny stuff I do not care who you are. Why would anyone park an RV in the shade if they use solar for power.

You are also a horrible shopper as you can get the MS 45 MPPT for less than $350

[Wrybread]

If it had been me in your shoes I would have spent the extra $150 on a Morningstar TriStar 45 amp controller that can input 600 watts with a 150 Voc input allowing me to connect the panels in series and not have all that incompatibility. That is what I would have done because I know what I am doing. No compromises needed.

It's pretty amazing, but this is more misinformation. The Morningstar TriStar 45 amp charge controller is a lot more than $150 more than the Tracer. The best price on the Morningstar I could find when I bought my controller was around $480, and I see it's now come down a bit to $420. Plus an additional $140 for the remote monitor, which is important for my setup. That's a total of $620 for the Morningstar. My controller was $165 plus $35 for the remote monitor, for a total of $200. If it was only $150 more for the Morningstar I probably would have bought it, but $420 more (over 3x the cost) put it in a different category, especially since the Tracer was well reviewed and fine for my specs (and in all likelihood will continue to be).

And just curious: if your solar array expanded beyond the capacity of the Morningstar that you magically purchased for less than 1/2 of its actual cost, would you then "not know what you're doing", because your plans changed?

And good lord I can't believe I have to repeat this yet again, but:

I cannot wire my panels in series because of shade issues.

Which necessitates a compromise. And it also means I haven't outgrown my charge controller in the first place. Even if I was wiring two of the panels together in series I wouldn't be, but that's beside the point. I'm adding one, maybe two panels to a single panel 300 watt system that's been working beautifully for coming on a year. I didn't expect to want to power the fridge off of it part time, or to have two panels basically given to me. But even so, the controller I purchased had plenty of headroom for exactly this sort of unexpected need, and I haven't outgrown it yet. And even if I do, it would hardly mean that "I don't know what I'm doing", it would just mean that it's time for an upgrade, which I fully knew was a possibility when I bought it. Compromises.

It's one thing to be an internet blowhard, but don't just make stuff up or mischaracterize people's statements to win arguments. And wow do you get into a lot of arguments, here and elsewhere. You obviously have a lot of knowledge that's useful to the solar community, but good lord is it obfuscated.

[Sunking]

I figured out a perfect solution: you buy me the $600 Outback charge controller, and I'll use it. Sound good? No? Ok, I guess the compromises are necessary then. For now at least.

Could not agree more with you. If it had been me in your shoes I would have spent the extra $150 on a Morningstar TriStar 45 amp controller that can input 600 watts with a 150 Voc input allowing me to connect the panels in series and not have all that incompatibility. That is what I would have done because I know what I am doing. No compromises needed.

[Wrybread]

No they are not. My premise is spot on; your equipment is incompatible and you do not know what you are doing.

Sorry, but not everyone here thinks my equipment won't work, just you. And sorry again, but you've been told by those other posters that you're wrong. As Sensij told you with superhuman tact:

However, there are some points in dispute in this thread that do not appear to be your finest work, and I've tried to chip in some clarifications. Time to move on to the next one, don't you think?

Let me know if you need me to translate that for you. Believe me, it would give me great pleasure to do so.

And furthermore, your alarmist and offensive language (not only to me) is way out of proportion with the topic.

You came wanting your system critiqued and you got exactly what you asked for. Now you want to moan about it because you did not like what you have heard from me and everyone else in all threads you have mucked up.

Wrong yet again. I got a ton of good info from this thread that significantly changed my plans. What infuriates you is that none of that info came from you.

If you want to make compromises that are not necessary, that is your problem.

I figured out a perfect solution: you buy me the $600 Outback charge controller, and I'll use it. Sound good? No? Ok, I guess the compromises are necessary then. For now at least.

I have been thanked 6 times today. How many times have you been thanked since you have been here?

Is there a 12 year old boy hiding somewhere in there?

And if this forum had a thumbs down button, what do you think your score would be?

[Sunking]

Both your premises are wrong.

No they are not. My premise is spot on; your equipment is incompatible and you do not know what you are doing.

You came wanting your system critiqued and you got exactly what you asked for. Now you want to moan about it because you did not like what you have heard from me and everyone else in all threads you have mucked up. You found out you do not know near as much as you think you do. The 4 to 5 engineers telling you that have close to 200 years of professional experience working with solar in one form or another. You have 20 years working under a shade tree on an RV.

Nothing more, nothing less. If you want to make compromises that are not necessary, that is your problem. I have been thanked 6 times today. How many times have you been thanked since you have been here?

[SunEagle]

Incidentally, I think you might be a good illustration of my theory that over complicating solar scares people away from using it. You're the moderator on a forum dedicated to solar, and yet your RV doesn't have a permanent solar installation. That's completely amazing.

.

Not really. I don't see solar as being necessary to enjoy my RV. I also don't want to mount the panels to my roof because I might want to park in the shade. Having my panels mobile allows me to move them into the sun and point them in any direction I want as well as "track the sun" if I choose.

Also being in Florida my wife (who really like the A/C unit) gets to be comfortable which means I have to find a place to plug the RV into the grid or use the genny. Which is just fine with me because it is pretty quite and does not use that much fuel.

Solar is a hobby for me. I have been rubbing elbows with it since the mid 70's when I worked as a lab tech in a research center at the University of Delaware during my senior year. I got credit for a senior project on studying sheet resistivity of Cadmium Sulfide Thin Film cells which also allowed me to co-publish a paper with the National Science Foundation. I still work on solar projects that are mostly Utility sized MW arrays. So I would say solar is in my blood.

I may not be an expert but with 40+ years in the electrical power industry and working with solar I think I have a little hands on experience to understand both sides of this technology.

[Wrybread]

Like I said he got on my radar claiming to have 20 years experience. You know what happens to pretenders here giving bad advice. 2 mods have told him he is wrong along with 4 engineers. He will not last much longer before they ban him if he keeps it up.

Ah, here come the straw men. I never claimed to be an expert, just that I'm not new to solar and have been working with solar (not professionally) for 20 years. It was you who injected "expert" into that, and then spent countless posts trying (in vain as it turns out) to make an upgrade that's still in the planning stages look foolish.

If you review your posts, your arguments boil down to:

- I'm wiring the panels in series and exceeding the specs

- or I'm wiring the panels in parallel because I don't know about the benefits of wiring them in series

Both your premises are wrong.

[Sunking]

Time to move on to the next one, don't you think?

Yes I do sensi. But let me ask you this. Do you recommend taking equipment to the edge. As a professional I cannot do that. If you buy wire like THHN to do 240/120 volt work what is it voltage rating? 600 volts right. Do you use THHN on a grid tie system operating at 500 volts? Most likely you se PV wire rated for 1000 volts because you do not want to take any chances. You are held responsible if something happens and would have no defense in a court of your peers pushing limits. So don;t ask me to do it.

I do not know the Temp Coef of his panels as it has not been specified. I do know about what it should be because all 300 watt panels are 72 cells and at 40 F you go over 100 volts and there is no way a professional engineer is going to endorse that any more than a doctor will recommend you smoke. Well maybe if you are over 60 with lung cancer in Hospice.

It is all a moot point with 3 panels, as 2 is ore than the controller can handle without clipping. 3rd panel is just a waste. Like I said he got on my radar claiming to have 20 years experience. You know what happens to pretenders here giving bad advice. 2 mods have told him he is wrong along with 4 engineers. He will not last much longer before they ban him if he keeps it up.

Not personal sensi, you have been around here long enough to know that. I will not tolerate unsafe advice, practice, and pretenders. Wrybread is all 3 of those.

[sensij]

Misinformation? It is called SPECS from the manufacture and proper safe engineering. Not SWAG from a shade tree mechanic.

From Page 22 of the manual:

Specs.JPG

Two panels, in series, in this location, meets both the 25 deg environment temperature requirement and the minimum operating environment temperature requirement for this charge controller.

I'm not agreeing or disagreeing with any decision the OP has made. Your knowledge and willingness to share that knowledge has helped a countless number of forum participants and visitors, even when your message isn't well received... that is not in question here. However, that are some points in dispute in this thread that do not appear to be your finest work, and I've tried to chip in some clarifications. Time to move on to the next one, don't you think?

[Wrybread]

> Misinformation? It is called SPECS from the manufacture.

Once again you've set up a straw man. The misinformation I was referring to is a) your theory that I think the Tracer is an ideal controller (I don't), and b) that I'm planning to wire the panels in series (I'm not).

Now lets all stand back and let Sunking formulate his next straw man argument.

[Sunking]

Yet more mind boggling misinformation from Sunking..

Misinformation? It is called SPECS from the manufacture and proper safe engineering. Not SWAG from a shade tree mechanic.

[Wrybread]

The Controller VOC is 92 volts. His panel Voc is 46 volts @ 25C. Personally I do not care if he wires them in parallel or series. He does not know what he is doing and you know it.

Yet more mind boggling misinformation from Sunking. I fully know my controller isn't ideal as I've said about 50 times now. But I also know that it's likely to work well enough for my purposes. If it doesn't, guess what: I can make adjustments.

Honestly, you might want to read up on the straw man fallacy. Its when you misrepresent someone's argument and then shoot it down. You do it *every* *single* *time*.