Just got to say it again, how it is we are sitting here for five months off grid on solar with no problems at all (third season on solar like this), using the non-programmable, non-MPPT, solar controller of the Series PWM type.Why do people insist on throwing money away on MPPT or even programmable PWM for kabillions of dollars when it gets you no advantage? You are being sucked in, you have a big M painted on your forehead (for "Mark") the salesman can see when you walk in? Beats me. :(You can program the fancy controller all you like, but you can't program the weather; every day is different, so what's the point?Get over it, I say! I am running 330w of solar using two separate arrays, one 130w and the other 200w, each with a 20amp LandStar controller cost $39 each. ( I could do it with one 30amp controller, but got the 20a first and then needed more amps when I got more panels- bad planning-cheaper to just get another 20amper than a new 30 amper ) The two controllers are in parallel on the one battery bank and it is just like having one higher amp controller--you can't tell. Perfect in every way! Classic three-stage charging even!You still have to "size" your solar set-up for your situation, but there is no need to get a fancy controller to get the performance out of it. You do need MPPT (way over-priced) if you get 24v panels instead of 12s. But do you really, really need the 24s? Is real estate that desperate? Note the little extra square footage per watt. Note the several small spaces on the roof and the few big spaces. 24v last resort thing IMO.Solar controller pricing is a total racket. Save your money for something worth while and don't be a sucker is the big lesson IMO.

Glad it is working so well for you!! Are the extra watts helping on marginal days when there are fewer hours of good sun?O&S has 24 v panel but has a 24v bank - PWM may just work well for him too.Jim

I gotta have 400+W minimum or else it's just a worthless trickle charge. I'm looking to make up for convection oven usage year round (one 230W panel would do it except in the winter). And since there aren't any 12V 200W panels, it's 24V or higher which means MPPT. My roof has stuff all over it but there is a spot for two 200+W panels to barely fit. Now if I could get 4 of those 140W 12V ebay panels cheap then that would work too but don't think I have the space for all 4.

Mena, somebody recently in another thread ISTR found 190w 12v panels.But whatever the biggest 12v, you can also get a bunch of smaller 12s and put them here and there that the big 24s won't fit.The big thing to remember is that you will not be doing 50-90s on solar; more like 85-95s with a chance to get to 98% some days. Lower amps area!Which means (do the math) you are only exercising a small part of your giant bank and you don't need all those watts you imagine. Think max battery acceptance rate in the 85-95 range for your size bank. What's the point of having so much solar that it can do 40amps if the batteries will only take 20? IE you don't need that big a bank as you have when solar conditions are right. (but they do vary! we also camp in winter)--Yes I have enough solar for various conditions, especially with my swivel contraption so I can point it at the sun if it only comes out part of the day at odd times as with North-West Coast routine.Note how yesterday I was able to get into Float at 98.5% SOC before 5pm and the start of heavy battery usage to make supper, watch movie, etc. How can anybody with a zillion dollar controller beat that? Can't. Which is my point. The controller is not needed to do any fancy stuff.

Some of us have MPPT because we can. Just like the size of our RVs, because we can. I could RV in a trailer but I won't. I could look at a smaller TV but I won't. I could have less than a leading edge computer but I won't. I could walk instead of riding my Segway but I won't. Different stroke for different folks. I don't hear any body condemning your life style. I was just as frugal as you at one time but now I don't have to be. Because I can!Richard

I figured 66Ah per day just for the CO. Once in the morning and once in the evening. What I'm looking for is for solar to replenish a good chunk of what is used from just the CO. The bank will still get used quite a bit. I probably should not have mentioned winter as we don't boondock in the winter and don't camp at all in December and January typically. Two panels would allow a longer stay PLUS CO use and maybe a longer CO use on typical trips. I get what you're saying about fancy controllers but the fanciness is not really about improving the charging, it's mostly about adding features to what will be an expensive controller anyways (I know if I was paying big bucks for an 80 amp controller, I want it do more than what basic solar controllers do). I liken it to new cars. Since the average cost of a new car is $30k in the US, the manufacturers can add expensive stuff to them because the added features helps to justify the higher price point (adding value).

Solar Controllers--Don't be a Sucker! :( | Good Sam Community

Salvo
Explorer
Jun 11, 2013
Here's some data on a solar panel I assembled over 10 years ago. There are 3 plots of solar short circuit current:

1. Panel perpendicular to sun
2. Panel flat on ground
3. Calculated sine of solar elevation

The x-axis is time in hours. x = 0 is when measurements are started, not associated with real time. y-axis is normalized current.

The flat plot never reaches y = 1 because the sun does not rise perpendicular to panel at that time of year (Oct. 18).

The last 3 measurements of the perpendicular plot shows how atmospheric dispersion kills solar power. Starting 1.5 hrs before sunset, solar drastically falls off.

Sal
BFL13
Explorer II
Jun 11, 2013
Mr Wiz, I heard you the first time, but I thought RJ's MH receiver mounted contraption folded up and stayed there while driving down the road. If not then of course it wouldn't work for you for the reasons you gave a while back.
pianotuna
Nomad III
Jun 11, 2013
Hi Jim,

Are you suggesting reflection is less of a concern with non glass covered panels?

HiTech wrote:
Worth adding is both angle because of cosine effect, but also agle because of reflection from the glass, which becomes the dominant loss for smooth glass panels at angles where the perpendicular solar output is still in the 25% range. I think people write off the benefits of morning and evening sun far too easily, because their yield with flat smooth glass panels falls off.

Jim
KJINTF
Explorer
Jun 11, 2013
Hi Jim,

Send me a PM with the details on the sun angle affects
Or if you have a larger document (word or similar) my email is at the end of the doc. Happy to add it to the next edition of the blog notes

Saw your thread on the many different kinds of PV systems
How about a guess at the PV wattage that differentiates the systems

I tend to use my array as a Power Source during the daylight hours
For me electrical power conservation is not needed
Typically no one within many miles of use so no issue with bothering camping neighbors. The boats trolling battery bank gets topped off every evening which again makes the controller go into MPPT mode. The GPS interfaced trolling motors sure are fun!!!
HiTech
Explorer
Jun 11, 2013
KJINTF wrote:
12thgenusa

I see my TS MPPT 60 do very similiar operation as what you described with your Rouge (Both excellent MPPT controllers). During a typical day we draw a lot of current from the system (I like to think the array is a almost unlimited power source as compared to a battery charger) The air compressor draws 25 amps, the stereo can draw as much as 15 amps, Swamp cooler 3amps, fans and pumps. This time of year the battery bank is almost always topped off at 100% by 11:00am, while the controller continues to switch between it's different operational modes all day long.

I put this document together a year or so back - not much new but might be of interest to others

Link

Nice write up! So many discuss neither spectrum nor temperature.

Worth adding is both angle because of cosine effect, but also agle because of reflection from the glass, which becomes the dominant loss for smooth glass panels at angles where the perpendicular solar output is still in the 25% range. I think people write off the benefits of morning and evening sun far too easily, because their yield with flat smooth glass panels falls off.

Jim
pianotuna
Nomad III
Jun 11, 2013
Hi Salvo,

I'm glad to hear the Blue Sky MPPT will essential operate in the same manner as the Rogue.

I don't fit the mold, but then I don't have a TV at all in my RV. I get to maximum output by flipping on the water heater. I do wish I had the 20 amp diversion load version of the BS3024. That would let me add a 12 volt water heater and the panels would work hard all the time.

Salvo wrote:
Thanks for the tutorial on the Rogue controller. But there's really nothing new here. It operates just like others.

You obviously don't fit the mold of your average camper.

I agree that a couch potato will be almost 100% in mppt mode.

12thgenusa wrote:

From this it obvious that a much higher percentage of time will be spent in MPPT rather than your estimated 20% or 50%, especially if one is creating demand loads. It's a shame if other controllers don't operate this way.
pianotuna
Nomad III
Jun 11, 2013
Hi KJ,

Lovely summing up. Thanks for taking the time to write it and post it.

KJINTF wrote:
12thgenusa

I put this document together a year or so back - not much new but might be of interest to others

Link
12thgenusa
Explorer
Jun 11, 2013
Salvo wrote:
Thanks for the tutorial on the Rogue controller. But there's really nothing new here. It operates just like others.

You obviously don't fit the mold of your average camper. Perhaps it's because you're new to the solar world and want to fully exercise it. We're not camped out in the "wilderness" to watch tv, but are there to enjoy the environment while hiking, mountain biking, windsurfing, sitting around the campfire, or what ever. In fact, I bet I'm over 80% of the time out of tv reception capability. And, you can only see so many movies. I usually limit myself to half a movie per evening. A good book works well.

I agree that a couch potato will be almost 100% in mppt mode.

12thgenusa wrote:

From this it obvious that a much higher percentage of time will be spent in MPPT rather than your estimated 20% or 50%, especially if one is creating demand loads. It's a shame if other controllers don't operate this way.

Wow! You can't just agree that you were wrong in your assumptions about MPPT operation. Instead you have to attack my camping experience, which by-the-way you are completely wrong about as well. Watching TV is probably the least thing that I do. If you watch half a movie every evening it's way more than I ever do. Why not keep the discussion on topic?
12thgenusa
Explorer
Jun 11, 2013
Good article, Ken. There is room for everyone's choices, needs and pocketbooks, but there is no free lunch.
Salvo
Explorer
Jun 11, 2013
Thanks for the tutorial on the Rogue controller. But there's really nothing new here. It operates just like others.

You obviously don't fit the mold of your average camper. Perhaps it's because you're new to the solar world and want to fully exercise it. We're not camped out in the "wilderness" to watch tv, but are there to enjoy the environment while hiking, mountain biking, windsurfing, sitting around the campfire, or what ever. In fact, I bet I'm over 80% of the time out of tv reception capability. And, you can only see so many movies. I usually limit myself to half a movie per evening. A good book works well.

I agree that a couch potato will be almost 100% in mppt mode.

12thgenusa wrote:

From this it obvious that a much higher percentage of time will be spent in MPPT rather than your estimated 20% or 50%, especially if one is creating demand loads. It's a shame if other controllers don't operate this way.

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