1st time ever planning to set up a solar system (265W Polycrystalline Solar Panel x 4)

[Hatorri]

I recently purchased from a neighbor a 2 year old used Polycrystalline 265W solar panels. He also sold to me his solar charge controller MPP Solar PIP-1012LV-MS/1000W Output/All in One Solar Inverter/Charger/Controller. Although I rather be using monocrystalline solar panels, I accidentally purchased these before I realized the mono's were black and poly's were blue. Since this was just a learning project, I figure I'll go with it and I didn't spend too much for them ($75 per panel, $30 for the PIP). My background is in EE and I did my special topic alternative energy course focusing on solar power but as I have read other forum posts, that doesn't guarantee that I will know all there is to know about setting one up (ie I did not know about using a BMS for the battery bank). This site also allowed me to learn how to buy the battery cells and how to put them together. I ran across this forum while watching some of Will Pros's youtube videos. As for the project in mind, I don't have a real target goal as to what I'd like this system to do yet but I do know that what I learn from successfully setting this up is that I will feel more confident when I decide to build a 23kW off-grid setup for my 5 acre farm. I'd like some assistance in this small solar project of mine. Thanks in advance.

I live in the South-East part of the US that lists that I get about 3.5 hours of direct sunlight a day. The total wattage of the panels I have, when wired together, will be 1060W at 36.6 Vmp and 7.5A Imp. I've researched on whether to put the panels in series or parallel and found that I will be going the parallel route due to the specs on the SCC. I reached out to MPP Solar to be sure and they said the parallel arrangement of 4 cells totalling 1060W does not exceed the max PV input Voc of 102V but the 500W PV Input/Output rating means the extra watts will be wasted. I read that over-paneling is ok and I figure I wanted to make sure that in the 3.5 hours of direct sun, I get the maximum I can get. The 4 panels in parallel calculates to the system being a 36.6 Vmp and 30A Imp. The SCC's max charging current is 40A so I'm good there. I tried to find out whether or not the SCC would be able to deliver the 30A given the wattage limitation of 500W. My calculations seem to tell me that the 500W limitation with a 36.6 Vmp means it can charge at a max of 13.66A. But some of the forum posts seems to make me think that the charge controller can dictate how much current it output. If this is the case, then could it output the 30A from my over-paneled setup? If it is limited to 13.66A or if it can deliver 30A for charging purposes, I have compiled a spreadsheet to tell me how long it would take to charge any given Ah battery that I choose to buy/build for it.

Since coming to this site, I learned it wouldn't be difficult to build a LFP battery. I was planning to order the EVE 3.2V 280Ah cells and build either a 4S bank or a 2P4S bank. I do have a question about whether there is a limit to how many batteries can be put in a parallel state. Is it possible to have to have each bank with it's own BMS (The recommended one was the JK-B2A24S20P) and be tied to the SCC? The person recommending the JK says they do not recommend this to be put in parallel but I see all over the forums that people successfully do this (attached parallel battery with BMS image). I also understand that there is a risk of damage but the forums indicated that this is not likely if using matched cells. I'm planning to get the cells from Amy Wan of Luyuan so I know they will be matched cells. If I only use the 4S with the 1 JK BMS, that would put the battery at 1120 with a max power of 14336W at 12V. With 50% DoD, it is 7168W usable. At 80% DoD, it is 11468.8W. I know with LFP's, it can handle 80% DoD but I calculated that it should last longer if using the 50% number. If I use the 4S battery configuration to get 1060Ah and if the MPPT can push out 30A to charge from my solar panels, it should take 35.33 hours (10.09 days at 3.5hr sunlight) to charge it to full. If the MPPT can only push out 15A for charging, it doubles the time it takes to charge to full. If I decide to build the 2P4S battery bank, then I take the numbers above and double the time it takes for 30A or 15A respectively.

The next question I have is the continuous wattage the SCC can provide. If I understand it correctly, I can draw a maximum of 1000W from the battery bank per our to do with as I would like but the MPPT can only charge at 500W to the battery. Does this mean that if I were to draw 1000W per hour, I would be using up the energy faster than the MPPT can store in the battery? My thoughts are that I would be using up more energy than what I would be storing in a day. To break even, should I not exceed 500W so that the battery? But if I want to follow the 50% DoD, should I just use 250W per hour?

I was looking at the newer MPP Solar SCC's and found they have improved and I could possibly get the models where I can parallel them. There are even models where it can provide 120V and 240V split phase.

If this learning setup works, then I will look at a 48V battery bank setup and use panels that have a higher Vmp and Imp.

 

[MichaelK]

This is a really wordy post that is hard to digest. You need to break your thoughts into more easily comprehensible pieces.

As a very new beginner, I would forget about designing a Li battery for yourself. Just go to Costco and buy yourself a couple of 6V golf-cart batteries and wire them in series. They are cheap, so if you trash them in the learning process it's no big deal.

Since your unit has a max charging amperage of 40A, I would not point all the panels in the same direction. Point two of the Southeast, and the other two Southwest, which will tend to flatten but broaden the daily amperage curve. In the real-world, expect to use a 85-90% derating value for your panel output. So assuming you have two panels making 265W (on paper), you should expect to see
[(265W X 2 panels)/12.5V charging] X 0.85 = 36A.

I would forget about pulling 1000W out of a 1000W inverter. Consider 500W a practical maximum. Someone with an engineering background should understand that you don't want to run any kind of equipment at the upper edge of it's rating for very long. Use at least a 2X scaling to meet your needs and expect long equipment life.

I would agree that you should eventually graduate to a 48V split-phase system. Exactly what do you think "23kW off-grid setup" means? Do you mean 23kWh of battery capacity, or 23kW of panels, or 23kWh of daily output, or 23kW of power output? They all mean different things.

 

[12VoltInstalls]

I rather be using monocrystalline solar panels, I accidentally purchased these before I realized the mono's were black and poly's were blue. Since this was just a learning project, I figure I'll go with it and I didn't spend too much for them ($75 per panel, $30 for the PIP).

You stole the setup at $330.
That aio is $500 delivered.

There is nothing wrong with poly panels- virtually the same effective usefulness these days.

MPP Solar PIP-1012LV-MS

Look up the manual. You are way overpaneled and will be best served 2S2P facing different directions BUT in southeast your tilt isn’t going to get you much.

I don't have a real target goal as to what I'd like this system to do yet

Well the unit sorta maxes at ~500W of simultaneous solar input or like 3kWr/day. You’ll get more and more later in the day/lower light being overpaneled.

total wattage of the panels I have, when wired together, will be 1060W at 36.6 Vmp and 7.5A Imp.

Look at the 1012 specs.

I've researched on whether to put the panels in series or parallel and found that I will be going the parallel route due to the specs on the SCC. I reached out to MPP Solar to be sure and they said the parallel arrangement of 4 cells totalling 1060W does not exceed the max PV input Voc of 102V but the 500W PV Input/Output rating means the extra watts will be wasted.

Use 2S2P, and angle a set of panels West for max late-day watts.

I read that over-paneling is ok and I figure I wanted to make sure that in the 3.5 hours of direct sun, I get the maximum I can get.

In that time period. But not unless you use it- you should use as much as you can above what’s needed to charge batteries.

calculations seem to tell me that the 500W limitation with a 36.6 Vmp means it can charge at a max of 13.66A. But some of the forum posts seems to make me think that the charge controller can dictate how much current it output. If this is the case, then could it output the 30A from my over-paneled setup?

No

If it If the MPPT can only push out 15A for charging, it doubles the time it takes to charge to full.

It can take 500W and make battery juice. At say 14.4V charging that’s theoretically 34+ amps but minus a few inefficiencies factors a wildhat guess would be 30A tops in practice

If I decide to build the 2P4S battery bank, then I take the numbers above and double the time it takes for 30A or 15A respectively.

The next question I have is the continuous wattage the SCC can provide. If I understand it correctly, I can draw a maximum of 1000W from the battery bank per our to do with as I would like but the MPPT can only charge at 500W to the battery. Does this mean that if I were to draw 1000W per hour, I would be using up the energy faster than the MPPT can store in the battery?

Yes
Basically it will make 1000W plus a bit more theoretical ‘surge’ but ignore surge. It will use wildhat guessing 1150W at 1000W output and my -MK model does ~45wH idle consumption.

My thoughts are that I would be using up more energy than what I would be storing in a day. To break even, should I not exceed 500W so that the battery? But if I want to follow the 50% DoD, should I just use 250W per hour?

50% of label Ah capacity is for lead acid. I’d rather bottom out higher than that for lead acid. Lithium can go 10%

I was looking at the newer MPP Solar SCC's and found they have improved and I could possibly get the models where I can parallel them. There are even models where it can provide 120V and 240V split phase.

Sure

If this learning setup works, then I will look at a 48V battery bank setup and use panels that have a higher Vmp and Imp

Sure. But those are a good setup for that. Run a subpanel and run your fridge, evac system,

Just go to Costco and buy yourself a couple of 6V golf-cart batteries

And MichaelK’s calculations are math not guesses that I did.

 

[Bobert]

There is nothing wrong with poly panels- virtually the same effective usefulness these days.

Absolutely poly is just as good as mono. Poly just takes up a bit more space than mono for the same wattage rating.