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I don't think it was necessarily a recommendation for a 300A rating. But what you're suggesting (a high-ish rated Class T to protect specifically against a dead short) isn't unreasonable, as long as you also have another method of protecting against the non-short overload case. So breakers...

Well I stand corrected on the panel voltage! Voc over 200V is a new one to me. This actually seems about right. This is 1/2 to 2/3 of Imp, and with a setting sun is probably not far from what you should expect. This seems to a be a common problem... The easiest way is to get a clamp style...

The 150/45 and VRM are fantastic. I haven’t built the rest yet, and may not for a few more years. I actually wasn’t planning on using the transformer to step up, just center-tap 240Vac to get 120V split phase. Electrical utilities step ac voltage up and down with transformers all the time, so...

Something doesn’t add up here. You said there are four panels wired in parallel, so how are you measuring 170-190V anywhere? Maybe these are very different panels than I’m familiar with, but I don’t think I’ve ever seen a single panel Voc much higher than 60V. Are you 100% sure that your...

You shouldn’t need both fuses and breakers. But you should be sure that you have real confidence in the quality of those breakers, and that they’re non-polarized. On the forum you tend to see more class T fuses than breakers because the fuses are much cheaper than high quality breakers. I...

The resulting battery will behave a little strangely at the bottom end: you’ll have eight cells in the lower knee of the charge curve and eight still in the flat part. So you might have the BMS cutting off when the battery voltage is higher than normal, maybe around 47 volts (just as an example...

I’ve seen worse here on the forum that have recovered just fine. Hook up the bench power supply and charge with low current, maybe 2 Amps, until the cells are all back above 2.5V, then charge normally.

If you have enough solar panels, yes.

I assume you mean three panels in series… In which case, don’t do that. You’ll exceed the SCC’s 75V limit on even a moderately cool day. Two in series would be fine.

What you have there is fine: 40A, 3.65V, 5A cutoff. You could raise the cutoff to 14A (0.05C), but the difference it makes will be small.

No, the two can operate independently of each other.

My point was that it currently makes sense for manufacturers to ignore the old ‘standard’ entirely. Because other than maybe for some RV applications, there’s no reason to make nominally ‘12V’ panels anymore. As for why stop following a standard that isn’t useful, that seems to me the wrong...

I would just ignore those nominal voltages. Years ago when people where using PWM controllers, 'matching' panels to battery voltages made sense. But MPPT controllers are cheap enough now that there's really not much reason to use PWMs. What that's done is made it so that panels don't have to...

It looks like this is a 15s battery. Charging to 53.5V (~3.57V/cell) should be fine. Ignoring Solar Assistant for a minute... What does the inverter report for these settings if you use its interface? It's a 48V inverter, so you shouldn't even be able to set it to have those values. The...

lol, for everyone's benefit... If @timselectric and I disagree, personally I'd go with what Tim said!

The battery wouldn't have something like that. Most inverters don't either. It's not necessarily something you need to 'install' exactly, though that is a common way of doing it and it's what I did with my system. Like @pollenface notes, there are lots of ways to do it: Bench power supply...

You can think of it this way: Your excess solar power is whatever power you would have made from noon until sundown if the batteries weren't full. You say you're power output is peaking at a little over 1kW, and a 9k btu A/C happens to use somewhere around 1kW, so you could run it for the...

Your inverter has big capacitors that need to be charged. This takes a small amount of energy, but without a pre-charge resistor it happens really fast which means a very high current; hundreds or thousands of amps. That high current can cause battery BMS’s to trip because it looks like a short...

Yeah, the panels are just all wrong for it. You need to have higher Vmp and run two in series, or lower Voc and run three in series. That particular Voc and Vmp combination doesn't work with a 100/20. You could use a 150/35 with three in series, or even four if you don't go below about -20C.

A few things: 1. Flexible panels don't have a good reputation on the forum. Apparently they don't last long and underproduce. 2. Do you actually need two battery banks, or can you power your 12V loads from a dc to dc converter? If it's just small things like LED lights, I would ditch the 12V...

The batteries will put off almost no heat, so the battery box can remain insulated year-round and it won't be an issue. As for the other electronics, I would just use some sort of ventilation that you can open for the summer and close for the winter rather than messing with removing and...

We need a little more information to give a good answer. But first pass: The inverter will probably run (and importantly, start) a 9k just fine. A 12k might be more difficult to start, but it's hard to say for sure. Really depends on the quality of the inverter. My 3500W SRNE (rebranded...

They have their place, but I at least mostly agree that ‘normal’ residential power isn’t it. Maybe in a big RV, or other mobile application where space is at a premium or where people want a simplified plug-and-play kind of solution. Like I said, I’m also slowly moving functionality away from...

Yes, the output from your inverter gets wired directly to your existing panel in place of the current grid power connection. The grid then connects to your AIO. Personally, I would probably have an electrician do the work of disconnecting the grid power from your panel and moving it over to...

If your AIO can provide enough power to run all of your loads, then there shouldn't be a need for a transfer switch. Either you're running off of battery/solar and the AIO powers everything, OR, you're passing grid power through the AIO to power everything. On the other hand, if your AIO can't...

Yep. And I'm not saying you should necessarily go with an AiO (I'll be installing a separate SCC to take over that function of my AiO), just wanted to point out that idle power draw will still happen. One additional benefit of an AiO that you may be overlooking is that they can eliminate the...

They won't do anything useful. What you're probably thinking you want them to do is stop one shaded string from pulling current from the others, but that's not what happens. A shaded string (or panel) still produces lots enough voltage to stop current from flowing backwards, it just won't...

This question is phrased a little strangely... Solar power from the SCC can power the inverter and if there's more power available than the inverter requires, that excess will charge the battery. Also, if solar is producing less power than the inverter requires, the inverter will discharge the...

Yup. There are two good lessons here: 1. Making power is hard, unless you’re in the business of fusing hydrogen into helium. 2. The sun blasts us with a truly huge amount of energy. So much so that harvesting 20% of any given area of it seems pretty worthwhile.

6.1A max at point A in a short condition. Regardless of which of the four panels fails. The string with the failed panel doesn’t contribute to the short current, it all come from the intact string.

Sounds like some sort of protection mode. You said the app reads fully charged, but I’m inclined to think it might be wrong about that. What voltage does the app report for both the battery as a whole and for each cell?

This is gold!

Exactly. And if ‘they’ (presumably oil companies) knew about it and were keeping it from ‘us’, they would definitely be using it in their own processes. And working in that industry for 20 years, I can assure you they are doing no such thing.

And here you are on a DIY solar power forum spreading ‘The Truth’, like you’ve got some sort of death wish. 😂 You’re either a moron because you’re seriously endangering yourself. Or you’re a moron because you’re just obviously wrong about everything you’ve claimed and are wasting your own time...

Yeah, as above: what is high voltage to you? I also run 48V nominal and I think it was the right choice. I see lots of people on the forum struggling with massive cabling for 12V systems that require hundreds of amps and I’m glad I’ve avoided that.