Any tips on my setup?

[Sunking]

it's just hard to believe, Sunking, that's all. I'll bear witness to it soon.

What is so hard to understand? It is 5th grade math and science. No technology can change physics, Watt Hours will alway equal Watts x Hours.

[-TX-]

it's just hard to believe, Sunking, that's all. I'll bear witness to it soon.

[Sunking]

All I got to say about that is, if I sit myself up on my roof from 8am-9pm I'd be dead at 6pm from sun exposure. Come May, the sun is EVERYWHERE in W TX. It is brutal. If PV can't take advantage of that than we're all wasting our time until competent tech comes around.

TX you are missing all of our points. Daylight hours does not equal sun Hours. A 100 wat panel only generates a maximum of 80 to 90 watts a few precious minutes around noon. So example in Lubbock TX in the months of June/July with optimum panel tilt and orientation is 6.5 Sun Hours despite 15 hours of day light. In December/January that drops to 2.75 Sun Hours. For a battery system you use worse case months the system is used in. So if you had a 100 watt panel used in December January the panel can only generate 100 watts x 2.75 Sun Hours = 275 watt hours. However that is at the panels output terminals and not all is usable, only 66% once you factor in all the system loses. So that 275 watt hours turns in .66 x 275 watt hours = 180 watt hours usable.

That is how you use Solar Insolation tables to design a system. Watt Hours = Watts x Hours. So if you need 1000 watt hours a day in Lubbock in December, you have to know Sun Hours so you can factor out the Wattage. So you look up the Sun Hours to find the panel wattage required. The formula that takes losses into effect is;

Panel Wattage = [Daily Watt Hours x 1.5] / Sun Hours. So let's run Lubbock to use 1000 watt hours and the system is use din Dec/Jan. [1000 watt hours] x 1.5 / 2.75 Sun Hours = 545 watts.

Lik eJPM said if you are going to play the game, you need to know the laws and rules. With energy it is the Law of Physics. Unlike man made laws, you cannot break or bend the Laws of Physics. If you could, you could jump over your house or flap your arms and fly.

Solar if a fully matured science and has not changed in 60 years. Does not matter if a 100 watt panel was made 50 years ago, today, or 100 years from now will still produce the exact same 180 watt hours usable in Lubbock.

[-TX-]

You just agreed with my comment about the tech being immature.

[J.P.M.]

All I got to say about that is, if I sit myself up on my roof from 8am-9pm I'd be dead at 6pm from sun exposure. Come May, the sun is EVERYWHERE in W TX. It is brutal. If PV can't take advantage of that than we're all wasting our time until competent tech comes around.

Lots of places are like that, and PV can and does can take advantage of the available insolation in effective but limited ways. However, and in spite of what you may think, things need to be quantified a bit more than you describe. That's just the way the game is run. The ante to get in the game is a bit of technical education. Suit yourself.

[-TX-]

Because you do not understand 10 hours day light does not equal 10 Sun Hours. Kwh / M^2 / Day = Sun Hours. Additionally you cannot compare a Grid Tied System with a Battery System. With a battery system you use December sun hours and a 66% efficiency with MPPT or 50% with PWM. Stick around, in 1 week here you have learned more in the last 20 years.

All I got to say about that is, if I sit myself up on my roof from 8am-9pm I'd be dead at 6pm from sun exposure. Come May, the sun is EVERYWHERE in W TX. It is brutal. If PV can't take advantage of that than we're all wasting our time until competent tech comes around.

[Wrybread]

First of all I never claimed to be an expert. I've been doing it for 20 years, but I'm very much still learning. And the fact that you don't know you're still learning is part of your problem.

And as I said over and over, I'm working with what I have. In my opinion that's extremely important to Rv solar system design. These things aren't pure theory. Sure things would be more efficient with a charge controller that costs $600 (or much more) instead of $150, but I don't want to spend that money on an RV installation. Especially when I don't need to.

Just as my battery bank would be more efficient at 24v, but that's another tradeoff I'm simply not willing to make for yet another massive increase in cost and inconvenience.

You keep insisting people don't understand you when they simply disagree with you. You might benefit from trying to understand people rather than calling everyone ignorant. And, worse, trying to scare the crap out of people. That didn't even come close to working on me thankfully, but I gather it's worked on others, costing them a massive amount of money and labor for questionable gain.

[sensij]

Two of your 300 watt panels wired in series exceeds the 100 Voc input of your controller. Hear that.

This is false if the temperature does not drop below -3 deg, and the panel performs as the data sheet says it will. The manual that *you* linked agrees that 2 panels in series can be acceptable for this configuration. Multiplying Voc by 1.25 is the safe thing to do when you don't have any more information, but the NEC agrees that if proper design temps and panel coefficients are used, a smaller Voc adjustment for a specific installation is valid.

You are applying rules of thumb to a system that is beyond that stage, and careful analysis shows that what the OP is proposing is totally viable, and an improvement over what he had. Is a 40 A CC going to outperform a 60 A? No. This aspect of the discussion is similar to the cost benefit analysis when choosing between an M250 and an S280 microinverter for an LG300 panel, for example. Yes, more power is available, but it might not be needed or worth the cost. Putting 900 W on a 40 A CC will produce more energy than if only 600 W are on that CC, and both configurations are well within this particular CC's specs. It is up to the OP to determine if optimizing beyond what he has now is worth it, but nothing he has suggested doing is fundamentally wrong and would result in system malfunction or failure.

[Sunking]

As I said about 50 times, I'm well aware of the drawbacks of flat mounting my panels, and wiring them in parallel, but for an RV setup with the equipment I have, I have to do it. I haven't "screwed myself" out of anything, and you using that language over and over exposes you for the argumentative troll that you are.

I have told you 50 times Flat Mounting Panels is not your problem. Never did I ever say it was a problem I am typing slowly so you understand. The problem is your equipment incapability and it all revolves around your Charge Controller. Wiring panels in parallel was antiquated 20 years ago with MPPT Controllers. Two of your 300 watt panels wired in series exceeds the 100 Voc input of your controller. Hear that.

Battery systems are best constructed with 200 and in some cases 250 watt panels because the Voc is low enough that allows you to at least wire 2 panels in series on 50 amp and less controllers. If you had 200 or 250 watt panels you could use your controler. Of th e12 volt controllers out there 200 and 250 watt panels fit nicely with 80, 60, 40, and 20 amp controllers. You should know why. Well here is your clue with a 12 volt battery the max power rating vs current is:

250 watts @ 20 amps
500 watts @ 40 amps
750 watts @ 60 amps
1000 watts @ 80 amps.

300 watts is not a common denominator. Additionally the charge controller manufactures Voc input is designed with 200 and 250 watt panels in mind although those rule of thumbs go away with high voltage controllers of 200 to 600 volts. Why High Voltage? Because it works better and smart money. At 48 volt battery you can wire 10 panels in series and limit parallel string to 2. That means a much more efficient system with a lot lower installation cost because you use a lot less wire. much smaller wire, no fuses or combiners.

Bottom line here is if you get rid of the POS controller, all your problems are gone with the minor exception of using 300 watt panels do not fit well, but can be made to work as long as you do not use a PRIME NUMBER of panels like 3, 5, 7, 11, 13, 17, 19.....

So am I being hard on you and others. Yep when you claim to be an expert of 20 years and do not know the basic fundamentals and cannot understand simple concepts. Grow some skin and balls. Bottom line here is you do not understand the technology or what you are doing causing you embarrassment claiming to be an expert. I called you out. Your low ball budget is costing you more to do it right and you only get half arse results screwing yourself.

.

[SunEagle]

If someone made a browser plugin that blocked all posts from SunKing, this forum would benefit greatly.

As I said about 50 times, I'm well aware of the drawbacks of flat mounting my panels, and wiring them in parallel, but for an RV setup with the equipment I have, I have to do it. I haven't "screwed myself" out of anything, and you using that language over and over exposes you for the argumentative troll that you are.

I'm through even reading your alarmist and overly dramatic "advice", and certainly done responding to you. Look at your posts from yesterday for example (not just to me, they were all over this forum, some so hostile that they were deleted by the mods), every single one of them is hostile and full of misinformation and reading comprehension fails, and failure to grasp that sometimes people have to work with the equipment they have at hand (not to mention budget).

You do have the ability to "mute" anyone that posts on this forum so you will not see their posts or have to respond to them. That is your choice.

[Wrybread]

If someone made a browser plugin that blocked all posts from SunKing, this forum would benefit greatly.

As I said about 50 times, I'm well aware of the drawbacks of flat mounting my panels, and wiring them in parallel, but for an RV setup with the equipment I have, I have to do it. I haven't "screwed myself" out of anything, and you using that language over and over exposes you for the argumentative troll that you are.

I'm through even reading your alarmist and overly dramatic "advice", and certainly done responding to you. Look at your posts from yesterday for example (not just to me, they were all over this forum, some so hostile that they were deleted by the mods), every single one of them is hostile and full of misinformation and reading comprehension fails, and failure to grasp that sometimes people have to work with the equipment they have at hand (not to mention budget).

[Sunking]

Yeah, I don't understand the math. How does 1.9kWh (PV) minus 14% inefficiencies equal 7 kWh of radiation in July, for example, when we get sun for 10 hours a day?]

Because you do not understand 10 hours day light does not equal 10 Sun Hours. Kwh / M^2 / Day = Sun Hours. Additionally you cannot compare a Grid Tied System with a Battery System. With a battery system you use December sun hours and a 66% efficiency with MPPT or 50% with PWM. Stick around, in 1 week here you have learned more in the last 20 years.

[Sunking]

Thanks, fantastically good to know.

It is a fools trap you have fallen for. Yes you can over power any MPPT controller to get a few more minutes of Sun Hours. But that is a FOOLS GAME. It is not a bad thing for a Grid Tied System, but throwing away money on a battery system. Also asking for over heating and equipment failures.

At very best if you parked in a Walmart Parking lot with no shade issues on a hot summer day will give you 5 Sun Hours with 0 degree tilt. With a 600 watt panel connected to a 40 amp controller only harvest you 1700 watt hours. However with a 50 amp controller that same 600 watt panel generates 2000 watt hours. You screwed yourself out of 15% of power. Add that 3rd panel with your 40 amp controller, sure it will work, you get 2000 watt hours. Use the 80 amp controller with 900 watts of panels and you harvest 3000 watt hours. You just screwed yourself out of 33% of your power. Then you compound your mistake connecting the panels in parallel screwing yourself again out of more power lost on wiring, and spending a lot more on wiring and hardware than you had to. All because your equipment is not compatible with each other. .

For someone who claims to be an expert with 20 years experience, you have not learned anything other than how to throw away your money on incompatible equipment. I would stop bragging if I were you, and start listening.

What is amazing is all you have to do to fix yourself is get rid of that POS controller you have and buy 1 compatible with your panels.

[Wrybread]

I think you would be better using all 3 panels, even if you stay at 12 V. Don't let the 520 W bogey scare you... look closely at the Page 10 Sunking linked. 520 W is the max charge power... in other words, that is the 40 A output spec translated to the input charge power, accounting for the efficiency of the CC. Even if your panels would be capable of producing more than that, the mppt system will pull the operating point away from the maximum, to stay within the 40 A output limit (as described in the preceding paragraph on page 9). In that same table on page 10, you can see that the max installed PV array power for the 12 V setup is listed as 1560 W, which is simply 3X the array charging power rating, although Voc and Isc limits might come into play as well as you approach that maximum.

By increasing the your array size, you are increasing the number of hours the batteries can be charged at 40 A. Your batteries will thank you later.

Thanks, fantastically good to know.

[-TX-]

Link? couldn't find that post