Why I Don't Over Panel My Solar Array (But You Might Want To!)

[@steverturnsk6190]

I started 2 years ago with 16 - 275 watt panels on my roof using four Victron 100/50 charge controllers. Since then I have increased to 25000 watts of panels with 18 or so charge controllers. The panels are set all around 13 acres of property, some directed east, most directed west for AC during the summer. One set of Trojan lead acid batteries (four 225 ah) and another set of lithium batteries ten 100 ahr. The house itself is off the grid 100% of the time and I use PG$E for the welder, lathe, air compressor. It is the shortest day of the year, rainy and the batteries are charged to 100% with the house off the grid. I use excess watts on sunny days heating a 1500w 120v heating element installed inside an electric water heater as a pre-heater for the propane water heater using a cheap 2000 watt dedicated inverter. Used 40 gallons of propane last year. The Victron 100/50 charge controllers are down to $180 now. Two of my charge controllers max out on the current for 1 hour a day in the summer; big deal, they have not burned up after two years of everyday use. 14 charge controllers are on the lead acid batteries (running large inverters) and 4 are on the Lithium batteries running 3/4 of the house circuits. Lead acid batteries cycle down to 90% each day and the lithium cycle down to 75% each day. All of those charge controllers work great together, with most taking the load and a couple on float, then changing as conditions change. It was an experiment that expanded into bigness. I could have saved some time and money if I were to have planned an entire system from the start. The inverters and charge controllers are the items that are somewhat consumable, and it is easy and inexpensive to replace an item if it fails. I retired as a marine engineer, and EVERYTHING eventually fails; known as Entropy, a law of thermodynamics.

[@TheOldJarhead]

Very well explained, Semper Fi brother!

[@OurBlackCatCottage]

Excellent video. I agree with you 100%. I have been running 4 charge controllers for years. Right before you said "why wouldn't you just put in another charger controller", I was thinking that exact thing. LOL. Well done.

[@TheOldJarhead]

Nice :)

[@ElectrabuzzXD]

Great discussion, thank you 👍 I really hadn't thought of it that way.

[@TheOldJarhead]

Thanks for watching and glad the video was helpful!

[@zoltanvonsomogyi7272]

Great show! Ive learned a lot from you. Thanks!

[@TheOldJarhead]

Glad it helped!

[@jime9305]

I think this is good sound advice...I've been running multiple controllers with separate arrays for years. It also gives you redundancy if components go out and and allows you to build a system in stages. But no matter what approach you take, at some point you will miss potential wattage either because the controllers can't use it or the battery bank is topped off. Plan any heavy electrical usage during peak hours and try to use it when available, thanks

[@TheOldJarhead]

Great point and advice

[@TheCornucopiaProject-bd5jk]

You pretty much covered the subject. There is one scenario where overpaneling might be beneficial. It’s when the array is far from the mppt. Overpanel and parallel combine two strings for a long cable run. There will be voltage losses and you might have very little waste by the time the power reaches the mppt. When running multiple mppt I suggest not to size them to the PV array, but instead make it duplicates of the largest mppt you need. It’s better for redundancy. Great video.

[@TheOldJarhead]

Thanks, Better for redundancy is a good point, one fails you can' move any of the others to the biggest array. Distance can be an issue but over paneling doesn't solve it really. Running series or series parallel is the key as you can get the voltage up high enough to not have much drop over the range on smaller conductors and with modern cc's accepting very high voltage it's no longer an issue like it was 15 years ago when most or many or the less than $1k cc's would only allow 150v or less.

[@WilsonForestLands]

I think what you are saying is the better idea, add more charge controllers. Since I have 170 feet of distance from the panels, I think that means I would have to run multiple expensive thick wires in addition to the one I have now. Maybe better for me to just to get a bigger charge controller if I add more panels. Or bite the bullet and buy more wires.

[@TheOldJarhead]

Or build a box and place batteries and inverter near panels and run 120v ac to the cabin

[@ktkace]

2 is one and one is none! redundancy + safety buffer ftw!

[@TheOldJarhead]

Amen!

[@gone51572]

So you can hook up two or three different controllers and have several panels and connect them all to the same battery Bank?? Am I understanding that correctly

[@TheOldJarhead]

Yes absolutely.

[@tedbolles]

Hey, while I understand your reasoning i overpanel some of my controllers,( I have 6 -40a epever mppt controllers) mainly because I lots of used 250w panels, so they are a little down on power ,my controllers are rated for 1040w, but I have 1500w going to them,I do have them split and facing a little bit different directions to get more out of available sunlite, trying to maximize each controller ,been up 2 years now no problem, I am in central FL.

[@TheOldJarhead]

That's not unsimilar to the principle of running series parallel for panel shading

[@GerbenWulff]

I have no experience with off-grid, although I'm considering either off-grid, but more likely hybrid as my next system. When I lived in Europe our HOA had a system with 20.9 kWp grid-tied panels and 17.5 kW inverter. The panels were in an east-west configuration. The inverter clipped the panels maybe a few percent of the time and only in the summer. In an off-grid system if you have plenty of power in summer, it doesn't matter if you lose a few percent power. What matters is if you can fill your batteries in winter.

[@TheOldJarhead]

You are correct, winter is the time when you need that peak power. But I argue there is still no reason not to add another CC. Sure, you won't clip much if any in the winter but you may if the panels are oriented correctly and the panels WILL produce more power in the winter than their rated power. Why waste it? Add a CC and capture all you can is my motto.

[@rickreese5794]

Thx O.J. H.😊

[@TheOldJarhead]

You bet

[@vevenaneathna]

ha i knew you looked familiar. im one of the pharmacists who used to work at the kettle falls pharmacy. im sure we have crossed paths before. i left a bunch of annoying comments on your videos over the years lol.

[@TheOldJarhead]

Hmmm I've been there before but didn't live there (Kettle Falls)

[@SolAce-nw2hf]

That is an interesting perspective on over panelling. I live in the Netherlands where the weather is pretty much cloudy for a large part of the year and solar panels are typically roof mounted because of the population density. Also going off-grid is simply impossible here because of the short winter days, so an on-grid or hybrid inverter makes more sense. My SW roof is slightly over panelled with 3250 Wp on a 3000W on-grid inverter so there is a little clipping there on some days. The NE roof has Enphase micro inverters and these only go to 300W per 430 Wp panel. This is not a limit they will ever reach because of the roof orientation and angle. I also have two panels on a shed roof with a very slight angle of 10 degrees. In real life these struggle to reach the 400W per dedicated MPPT even though the panels are rated at 450 Wp. In your situation it may make more sense to have multiple MPPT's as space is not really a restriction and solar panels are still relatively expensive there. But in the Netherlands a 450Wp solar panel can be bought for 50 dollars now, so just filling up the roof with all it can take really makes sense compared to the extra cost, even if the inverter does not use all of it all of the time.

[@TheOldJarhead]

Great points! On the roof, I'd still run multiple CC's because there is always the summer ;)

[@SolAce-nw2hf]

@ The summer is not actually that great. High temperatures really affect the solar panel production. Even with full sun it often peaks only at 2800W with the 3000W inverter. The month of may is much better with colder but still sunny weather. At the time my solar installer told me the lower peak power was not actually an issue leaving at most 2% of the yearly production unused. A bigger inverter, a heavier breaker and thicker cables would cost me more than it was worth. I am considering swapping out the inverter for a hybrid one. I could upgrade to a 3600W model without any other modifications and with the connected batteries that would be usefull to help cover peak usage in the kitchen when the sun is not in it's optimal position anymore. With the net congestion issues and net metering coming to an end it makes sense to store and cover as much as possible. But for the solar panels themselves any expansion is a waste of money. With all of the other panels combined the solar production is about 3x my usage in summer. In december it is not even enough to power the fridge 😱

[@TheOldJarhead]

Why move to a hybrid? Why not just put in a new inverter? Or do you not do any of the work yourself? In summer, above the 48th parallel I can produce power for hours and hours but yes, in the winter my production drops significantly. I don't see the sun much before 10am (I'm guessing you are well above me in the north in Norway?) and it's pretty much behind the trees by 3pm vs the summer when production on my panels begins very early (even before 7am) and can last well into the late afternoon/evening and that's without east/west facing panels. Further north, with snow, I'd put in BiFacial panels and catch more solar production by getting reflection off the snow :)

[@SolAce-nw2hf]

@ with a hybrid inverter I can directly connect a battery preventng DC-AC-DC conversion. Right now with the net metering the grid is my battery (with seasonal storage 😂), but in 2027 that government incentive is coming to an end and the energy companies are already bypassing it with extra costs for every kWh, so when my current contract expires it becomes something I want to do, even if it just about breaks even until 2027. I also want to help shut down dirty coal power plants and there is no better way to do that then by eliminating my grid demand 24x7 for about 8 months a year.

[@TheOldJarhead]

ahhhh yes, I don't do grid tie so out of my element

[@BeeBeorn]

In my opinion, having several, more than one at least, systems is important. And, that for your specific need deemed critical, like freezers, waterpumps , has dedicated seperated systems. Well designed and not tampered with after production start. Everything else can be played with.

[@TheOldJarhead]

Yup 👍

[@adamwiseman5831]

Good points

[@TheOldJarhead]

Thanks! Glad you liked it! Always cool to chat about solar stuff!

[@AverageJoe2023]

Can you show us how you wired your 2 controllers to one battery bank?

[@TheOldJarhead]

I can do that but b4 a vid. I use a Midnight Solar DC Breaker Bix for that

[@AverageJoe2023]

@ I’d appreciate it. I’m still gathering equipment as I live in town with no space. Just trying to get myself enough knowledge and equipment as I can before I have the ability to hook things up. Great video.

[@TheOldJarhead]

Might be a good one for a live

[@junkerzn7312]

I generally agree... just add more charge controllers. At least if the extra cabling isn't a chore to run. Not everyone thinks ahead. Even though I'm only using two MPPTs at the moment, I actually wired three cable pairs to my roof for future expansion precisely so I could add a third later on. That said, there is a very real danger to over-paneling which I will describe. I'm not saying it shouldn't be done, I'm saying that you have to make another calculation and ensure you don't exceed it. The main problem with excessive over-paneling is that the charge controller can only handle so much current on its input. Yes, the input. Not talking about the output here. The input. This may seem a bit odd but it's the real reason why charge controllers can fry when over-paneled but the voltages remain in bounds. You CAN over-panel safely, in my view, but you must still adhere to the current limitation of the solar input. The current limitation of the solar input is typically the same as the current limitation of the battery output. So, for example, if you have a Victron 100/20, the charge controller itself will regulate the output to no more than 20A and over-paneling beyond that isn't a problem... the regulator will limit the output (though it might spike over every so often, this will be short-lived). BUT the MPPT voltage sweep on the input is another story entirely. The circuit shares the same heat sink as the output and is typically limited to the same amperage... 20A in this case. And the FETs have a junction temperature-v-time gradient limit that no heat sink can fix. Which means that if you have, say, residential panels capable of outputting 15A, you absolutely cannot put them in a parallel configuration such that the voltage sweep puts 30A into the solar input of the charge controller. (Using the Victron 100/20 as an example). That's the real limitation. Stay within the voltage specs, but also stay within the current specs on the MPPT input. For a Victron 100/20 you can parallel 4 x 5A panel strings, or 2 x 10A panel strings, but only one 1 x 15A panel string safely. Its perfectly fine if the total possible wattage exceeds the rating of the charge controller, it will just regulate the output to its rating. It is NOT fine if the total possible input current exceeds the rating of the controller, because the voltage sweep is NOT going to regulate the input current. That could blow the FETs or melt something. -Matt

[@TheOldJarhead]

Great insights! You're absolutely right about the importance of understanding the current limitations of charge controllers. It's crucial to plan for future expansions while keeping those specs in mind.

[@jime9305]

I don't think this is true....there is a overcurrent recommended input limit but it not the same as the rated output, it's higher (at least on Victron controllers)

[@TheOldJarhead]

I think this is more of a controller specific issue, but I'm not 100% certain

[@Sylvan_dB]

Charge controller needs to be near the batteries. Wire from panels to charge controller adds up quick if you need to have the panels a few hundred feet away.

[@TheOldJarhead]

Yes but 59 to 100 feet isn't an issue. Beyond that and cable gets expensive and heavy no matter what

[@1GREATDANE]

I AM CHEAP and Adhere to Head Room on each Array / Charge Controller so I Don't get that Black Smoke 💨 💨 Thank You for another Informative Video 🌴 Marine 🇺🇸

[@TheOldJarhead]

That's the way to do it, 👍

[@kr639]

I have a different definition of over paneling…. Not much to do w the charge controller but rather more wattage as to not worrying about tilting or needing ground panels

[@TheOldJarhead]

Basically the same thing -- increasing the total array wattage to above the SCC's rated wattage when you know it's unlikely to have to clip it, or it will clip very little but get closer to the peak wattage for longer.

[@andrievbastichy8551]

nice video.

[@TheOldJarhead]

Thanks

[@jameswilsin5348]

You only get 80 percent power from a 100 watt and any other panel if you get 100 watts out of a100 watt panel let me know what brand and how much it cost

[@TheOldJarhead]

I've gotten 673w out of a 615w array.

[@Sylvan_dB]

Cold (well below 0C) on a nearly clear day (a few wisps of clouds is better than totally clear) is optimal. On such a day I've often hit peakers more than 10% above panel ratings. The highest I've noticed I was rooting for it to hit 20% but the highest I saw was 17% more than rated. The cold keeps the panels fully productive, clear means more sun, and there is a "cloud edge effect" where the cloud acts like a lens and the sun is brighter at the edge.

[@TheOldJarhead]

When I hit 673w on my 615w array I was at 109.5% of expected production and it was a warm early fall day. So I will have to try to catch production in the winter when the suns up to see what I get but even on a warm 70F day my poly panels can over produce.

[@justinmitchuson8992]

Victron , overpaneled 1.5 . 🏆

[@TheOldJarhead]

50% over?

[@mr.monitor.]

Most panels seem to put out about ~ 50% of their ratings most of the year on average. Being over a little bit on wattage is going to be ok.

[@TheOldJarhead]

My panels put out their rated wattage pretty much every sunny day. If aimed right, they should meet or exceed ratings or they are not well made.

[@mr.monitor.]

@TheOldJarhead I have several different brands. You must have magic panels.

[@TheOldJarhead]

Perhaps you don't understand panel ratings? They only put out rated power when correctly placed (right angle and azimuth) at peak solar and are rated typically at 70F. In hotter temps they produce less power, colder, more, poor angles or azimuth, less etc. Rated power is just what they can produce and likely is only hit at solar noon if placed correctly to catch it. The rest of the time they are limited by where the sun is in relation to where they are facing and impacted by temperature, shading, hazy skies etc etc etc.

[@mr.monitor.]

@@TheOldJarhead I do understand that. However you are claiming yours are putting out more than their ratings routinely while nobody else is.

[@TheOldJarhead]

No, I simply stated that I have seen them hit 110% of rating on a fall day in 70F Temps (which the astute would know is not optimal for over production) and that I've seen them produce there rated wattage many times over their near 15 year life. Furthermore. I explained that they are also poly panels which are known fir high production

[@jasonbroom7147]

When you over-panel, it gives you the ability to get SOME production on days when you would otherwise get virtually zero production. You can't do that with more charge controllers, you can only do that by having a high enough voltage potential (still well within your charge controller specs) but more amps from that string. Break that up with more controllers and you only get more controllers bringing in nothing. This isn't theory or conjecture; people who LIVE off-grid see the results of this during every cloudy winter day. Have you tried it or did you decide over-paneling was just "bad", and never tested it for yourself? Cuz, uh...if you had, you would abandon this hill instead of dying on it.

[@TheOldJarhead]

As I'm above the 48th parallel at 3200 feet in elevation on a north facing slope, I've had my experience with winter and cloudy days living off grid. You're assumption here, is that over paneling is the solution to cloudy low production days but it fails to see the errors in it's theory. Voltage. Yes, getting the voltage up high enough that the amperage produced by the panels produces enough power to provide a charge for the batteries matters but that's the case every day of the year. It's just harder when it's cloudy and in an off grid system you build for it by increasing battery bank size (I did mention this is for off grid only folks) and arrays that face different directions, even is just slightly. Bringing the voltage and protentional amperage up to a level that will allow production in low light situations has nothing to do with over paneling and everything to do with engineering a good system and I don't need to risk over paneling or having just one controller because my system can produce power all the time and has the battery bank size to allow me to go days without solar production with a generator to back it up if it's a really dark winter. The only reason to over panel is to try to get more production out of a single array for longer and at peak wattage of the controller. Voltage is a function of the panels and their configuration, not the controller, the controller is the limiting factor.

[@jasonbroom7147]

@@TheOldJarhead - The only reason NOT to over-panel (within reason) is to avoid excessive clipping during peak summer production. I guess if you have enough room to put up lots of extra panels, facing different directions, each with their own SCC, you can avoid the (non-existent) risks of moderate over-paneling. Having done it for several years, I know for a fact that I get more total production, from a certain number of sq/ft, by over-paneling. How or why that would ever be a bad thing, when your SCC will limit amperage that exceeds it's total wattage output, eludes my simple brain.

[@TheOldJarhead]

I didn't say it would be a bad thing, and later in the video, I also discussed where it may be right for some. Perhaps you didn't watch it all? I get what you are doing, I just see a different way to achieve more production and have been doing it for over 14 years.

[@jameswilsin5348]

You can have 2000 watts solar panel you will not get 2000 watts I know I did my research I got 4 systems and got 400 watts getting 100 percent Sun and most I get is 295 watts

[@TheOldJarhead]

Sorry, incorrect. I've gotten quite a bit more but have good poly panels

[@TheOldJarhead]

kzbin.info/www/bejne/pl7Gc4mbnJV5l8k

[@ZuluHour]

Currently using/testing Ecoflow products. Have two 400W panels that can power and charge the system on perfect sunny days, inputting (combined) over the “maximum” 800W. Respectfully, if you aren’t getting maximum wattage, it’s most likely operator error.

[@TheOldJarhead]

Or poor quality panels perhaps but yes.

[@mr.monitor.]

@@TheOldJarhead You either don't understand mathematics or have magical panels. There is always that one guy that gets 20 mpg with his stock 3/4 ton 1980s V8 while everyone else gets 8 mpg mysteriously 🤣 . You are about the only person claiming panels regularly put out over their rated wattage.