Simple system but I need help with it.

most of your mppt controllers will need batteries, some of the bigger ones might not, but you will need more than 400w of panels. Startup voltage is high on many of those. You are outside of "cheap" with them. The only micro inverter I am familiar with is hooked to 2 of my 100w panels and feeds "up to 1000w" into my "local house grid". Of course with 2 100w panels feeding it, I have only seen it feed about 400w in. Not the safest thing to use, in theory it could feed too much current into the working side of the circuit and exceed the breaker rating if your are using the circuit to high levels.

Hogheavenfarm said:

2 of my 100w panels and feeds "up to 1000w" into my "local house grid".

Click to expand...

I don't see how 200W of panels could feet 1000W into a grid.
Do you mean 1000Wh?

Ronifer said:

Do you have any knowledge on how the micro inverters work?

Click to expand...

They pretty much just convert panel DC to AC up on the roof. Normally they are daisy chained and produce 240V here in the US (L1, L2, N). They do not produce anything without sensing they are connected to a grid or an islanded grid created by an inverter.
This AC power can be fed directly into breakers in your house or into many inverters that are AC couple capable.

Have mine feed a sub panel. What i don't use as it is being produced spins the meter backwards. How that is accounted for by your meter and your utility can vary significantly.

Good day to all. I've completed my audit after updating the appliances and maybe calculated and designed a reasonable system. If someone has a better way or less expensive I am all ears. I'm hear to learn and make friends with the same interests.

3 combined appliances over 24 hours showed ~
Start amps: 10.39a
Running watts: 206w
Wh/day: 2310Wh

Equipment List:
Ampinvt charger/inverter 800w continuous 2400 peek

60Amp Mttp charge controller 12v accepting a 900w array

8x 100w 12v eco-worthy panels

2x 12v80ah interstate deep cycle batteries.

I already have those batteries that I seldom use that are fairly new so why not?
Parallel both the battles as well as the panels.

So what do guys and or gals think? I really appreciate each ones help. I attached a picture of how I wished solar panels worked ?

Thanks for your input as always!

Ronifer said:

3 combined appliances over 24 hours showed ~
Start amps: 10.39a
Running watts: 206w
Wh/day: 2310Wh

Click to expand...

Not sure what you mean with this. What is "start amps: 10.39a"? Amps is a rate so how long and at what voltage?

Running watts: 206W - also a rate. How many hours.

2310Wh / 24h = 96W average run for the day

Is 2310Wh your daily use? We can use that, i just cannot tell how you got that number (none of your other numbers make sense).

Doesnt sound like "start amps". Surge will peak within a second or less, the killowatt meter will not normally record that, mine doesnt. I see it on my shunt meter at startup. My small freezer surge is 734wh (saw it last night) for a quick second then immediately goes to running watts, (114wh). I know the big freezer surges to 824wh for a split second, then drops to 83wh. (so 10 x estimate for surge seems about right).
My only concern is that your inverter may be a bit low to handle multiple starting surges, but maybe not.

Yes MisterSandals - I meant wh. I don't have it hooked up any more, just going by memory. Didnt run the meter backwards but slowed it down a bit, some days the daily reading would be 1kwh.

MisterSandals said:

Not sure what you mean with this. What is "start amps: 10.39a"? Amps is a rate so how long and at what voltage?

Running watts: 206W - also a rate. How many hours.

2310Wh / 24h = 96W average run for the day

Is 2310Wh your daily use? We can use that, i just cannot tell how you got that number (none of your other numbers make sense).

Click to expand...

Starting amps is what I called the max it pulled. That was at start up. Only lasted a few seconds for each appliance. 206 watts combined while running. 60+49+97=60 watts while all 3 are running. Total watts for all 3 in the 24 hr period was 2310whrs. 2.3kwh per 24 hours.
Is that not correct?

Hogheavenfarm said:

Doesnt sound like "start amps". Surge will peak within a second or less, the killowatt meter will not normally record that, mine doesnt. I see it on my shunt meter at startup. My small freezer surge is 734wh (saw it last night) for a quick second then immediately goes to running watts, (114wh). I know the big freezer surges to 824wh for a split second, then drops to 83wh. (so 10 x estimate for surge seems about right).
My only concern is that your inverter may be a bit low to handle multiple starting surges, but maybe not.

Yes MisterSandals - I meant wh. I don't have it hooked up any more, just going by memory. Didnt run the meter backwards but slowed it down a bit, some days the daily reading would be 1kwh.

Click to expand...

My starting amps for each showed instantly but fell rapidly. Just 2 to 3 seconds. Amps while running after falling were much lower. Starting watts were 650's all together just about every time I tested. At 2400 peak that still may not be a large enough inverter?

Just sounds extremely low to me, maybe fine if thats what it is. Only way to find out for sure is to try it. If you plan on expanding the system though, you may want to consider a larger inverter, the prices of inverters in the range 500-2000 watts is pretty similar, 2500 is a small step up and is pretty much the max used for a 12v system due to the heavy gauge wiring needed, I wanted the "one and done" option because I plan on expanding, so I went with the 3500w and 24v.

Hogheavenfarm said:

Just sounds extremely low to me, maybe fine if thats what it is. Only way to find out for sure is to try it. If you plan on expanding the system though, you may want to consider a larger inverter, the prices of inverters in the range 500-2000 watts is pretty similar, 2500 is a small step up and is pretty much the max used for a 12v system due to the heavy gauge wiring needed, I wanted the "one and done" option because I plan on expanding, so I went with the 3500w and 24v.

Click to expand...

Yes sir the numbers are low. My old appliances were much higher. We only replaced the oldest freezer 1993 and the old refrigerator 1995. The 2008 upright will just have to stay for now. It is the biggest consumer of the 3 coming in at accounting for 6.32 amps from a cold start and a whopping 1,060kwh per 24 hours. It's just under being half of the load combined. I ran the numbers and it wasn't practical to spend another more money replacing it just to operate on a slightly smaller system. Maybe later on we can replace it and then my total drops around 1.85kwh for the 3 combined. That would allow more room for overcast days if I go ahead and plan for the hog and have a supper later.

400bird said:

Start up surge on the compressors can be 5x running current

Click to expand...

My 7.4cf fridge hums along at 60-80w. But startup surge is 600-800W, usually for less than 2 seconds but I have seen it go for 30+ seconds.

5x startup surge is less than what I’ve usually seen suggested, which is 10x. 10x is in alignment with my experience.

So assuming @Ronifer has three refrigeration devices that all start up at the same moment, I would be looking at low frequency inverters of around 1500-2000W with a real surge ability.

If it’sa cheap high frequency inverter, you can bet that the surge ability is useless in most cases including the surge requirements of a freezer or fridge.

That was my concern, just from my own experience, thats why I chose to overengineer my inverter rather than "burn one, buy two". But if thats really the actual startup surge, maybe it would work.

Thanks guys I am going to make certain the start up watts are in line for sure. The freezers don't cycle much. They run quite a while as in most of the day and none or very little at night. The hog used 380 watts over night one night and the mini fridge for just about long enough to say it did at 40 watts.
I bout 3 meters and have been testing in 24 hours intervals but taking a reading every 12. I've been playing with the times as in 6 to 6 , 7 to7 , 8 to 8 and I also checked during peek sunlight hours only. Which right now in South Georgia is from about 11:30 to 3:30 with sun being in transit at 1 pm. I did that just for giggles. I chose that inverter because it was 12v. It seems hard to find one of any larger size that is 12v that is a AIO. Maybe I'm not looking in the right place?
Thanks y'all and I will post when I get them cold start watts together again.

Ronifer said:

Thanks guys I am going to make certain the start up watts are in line for sure.

Click to expand...

Keep in mind that unless you’re buying an expensive inverter (think Victron, Schneider, etc), then the surge rating is a lie. My 1000W Victron can surge for up to 2200W for up to 30 seconds. And I think even higher for that for 5 seconds or less. An expensive inverter is HEAVY due to the massive low frequency transformer coils inside the inverter.

If you read the fine print (if they even print it) of a cheap inverter, you’ll learn that the surge rating is only good for less than 1/4 of a second. That’s not long enough of a surge for most devices that surge, like refrigeration equipment.

Your solar has to make enough in a 'solar day' to cover all 24hrs of consumption, but more specifically it has to SIMULTANEOUSLY make enough to power the loads during the solar day, while recharging everything that was used since the last sunset. So if you had 200w of continuous load and 6hours of solar, you'd have to have 200w ON TOP of putting back the 3600wh from the previous 18 hours of no solar! So 3600wh / 6h = 600w PLUS the 200w to KEEP the loads running, you'd have to average at least 800watts during the solar day. But ideally you'd leave a lot of margin for bad solar days, so you may want to have ~1500-2000w coming in! So you can see how a 200w continuous load pretty quickly escalates to 'thousands of watts' of solar to make that system reliable.

Vigo said:

Your solar has to make enough in a 'solar day' to cover all 24hrs of consumption, but more specifically it has to SIMULTANEOUSLY make enough to power the loads during the solar day, while recharging everything that was used since the last sunset. So if you had 200w of continuous load and 6hours of solar, you'd have to have 200w ON TOP of putting back the 3600wh from the previous 18 hours of no solar! So 3600wh / 6h = 600w PLUS the 200w to KEEP the loads running, you'd have to average at least 800watts during the solar day. But ideally you'd leave a lot of margin for bad solar days, so you may want to have ~1500-2000w coming in! So you can see how a 200w continuous load pretty quickly escalates to 'thousands of watts' of solar to make that system reliable.

Click to expand...

The panels produce way more than 6 hours per day here at some capacity.
I'm calculating for 4 hours peak though.

On a great winter solar day I am hoping the 800 watts of panel will get me 2560 watts in a day. And yes I understand the take out has to be put back in and there has to be extra juice for battery filling. I'm thinking I will be covered since the run next to none at night for the most part and none of them run at the same time during the day for the whole day. There is down time that allows for the power to charge rather than run/draw power. If it were a 24hr hour a day drained I am sure I'd be pushing it on not so good days for solar. I have grid and am not dead in the water and should that go down I have an 8500 continuous watt generator on hand that I use for my home improvement business so I'm covered should anything power out.
Buy my calculations I should have enough solar and battery to run all 3 for about 13 hrs and most of that running is done during the day. I did recheck the watts at start up and it shows the 3 pulling 1,350 watts this time but that may be because I unplugged them while running and restarted them within several seconds. I am guessing that's an extra pull that effects watts and possibly damage your compressor. With the 1500 watt continuous with the inverter I am looking at and a 3,000 watt peak capacity I'm certainly hoping it can handle a load less than one space heater. My 1500 watt juniper pulls 1500 watts with no problems but isn't a pure sign wave. I hate to throw money at more than I need at a 200 watt continuous load. In summer it's more like 6 to 7 peak hours on our longest day so I should on a good day generate 3840 watts per day? I would think so. My full usage isn't 3.6kw per 24hr day it's 2300kw per 24 hr day. I realize that's cutting it close but I'm on the grind and the ever has a grid charge mode.
This inverter seemed like a good fit, maybe I'm wrong but it seems to have a lot of features. Everything comes from China just about it and much of it is cheap junk I agree. I am still shopping on inverters to make a best possible decision on one. Thanks for the guidance!

I definitely think you are on the right track. I was being very general, and i agree your ACTUAL measured consumption and the nature of the loads makes your setup a little easier. Sorry if my post came across as doubting you. I think youve got a handle on it.

Ronifer said:

I hate to throw money at more than I need at a 200 watt continuous load.

Click to expand...

I hear ya. But the continuous load of your compressors is not a useful number when it comes to sizing an inverter for powering three compressors that could potentially start at once. The startup surge of the sum total surge of your refrigerators and freezers is the number you need.

You measured (with what tool?) that your three devices at surge are pulling 1350W. That seems a bit low to me. I would go more conservative and look for an inverter that can provide 2000W continuous (ignore the surge rating). You can go with a cheap inverter here, the main downside will likely be a higher idle draw. I doubt you’ll pull more than 1800-1900W if all three start at once. You can try a non pure sine wave inverter, but it will shorten the lifespan of your three compressors and probably make them run more loudly.

Tomthumb62 said:

I hear ya. But the continuous load of your compressors is not a useful number when it comes to sizing an inverter for powering three compressors that could potentially start at once. The startup surge of the sum total surge of your refrigerators and freezers is the number you need.

You measured (with what tool?) that your three devices at surge are pulling 1350W. That seems a bit low to me. I would go more conservative and look for an inverter that can provide 2000W continuous (ignore the surge rating). You can go with a cheap inverter here, the main downside will likely be a higher idle draw. I doubt you’ll pull more than 1800-1900W if all three start at once. You can try a non pure sine wave inverter, but it will shorten the lifespan of your three compressors and probably make them run more loudly.

Click to expand...

Indeed the numbers are low but they are what they are. I've tested with a killowatt meter and confirmed it is accurate with a friends clamp on meter. Two of the appliances are a week old and are soft start. You can barely hear them run. If I were to swap out the only old appliance in the bunch the consumption would be about 1,520kwh per day. I'm just going to build for what I now have as I just dropped $600 updating appliances already just to get the numbers down that were extremely high with a 1993 21cuft upright, a 1995 side by side fridge and a 2003 upright 15 cuft. That would have taken double of what I am looking at needing now. People don't realize just how much 20 and 30 year old inefficient appliances burn. I knew it was more but I sure didn't realize it was that much. But the numbers don't lie. And I wouldn't connect a nasty inverter to any modern appliance for long. We use the only one we have for a cheap coffee makers while camping. That's it. I can't justify in my mind knowing that my max load is 1350 watts buying a larger inverter knowing 2400 watt peek is the stated capacity of the one I am looking at. I'm 1,000 watts away from max and will be even farther after getting the 2003 replaced which I plan to do in the future after I get this hut operating on solar and get that paid for. I figured after that my system will be very ideal and dependable to stay off grid shot of inclement weather. In that case enough days of that and nobody has enough regardless. Now if I was off grid then I would opt for more array as well as battery but why should I? I have grid as well as a rather large generator. Plans B and C. The old appliances were consuming 7kwh per day. I think I can accept a .5kw grid supplement for a day or even 2.3kw should it go offline for a day. It's simply not worth it to me to buy a huge bank for a small load to run as if it's my sole means of survival which it isn't. If I have enough capacity to have these power by solar and battery 90% of a year I will be happy. Thanks for your help and guidance!

Vigo said:

I definitely think you are on the right track. I was being very general, and i agree your ACTUAL measured consumption and the nature of the loads makes your setup a little easier. Sorry if my post came across as doubting you. I think youve got a handle on it.

Click to expand...

Not at all sir. I value your opinion and knowledge. I'm getting a much better understanding of how to size a system now. In my mind I was thinking cover the day load and a little extra to charge just enough battery to get me through the darkness each day. But that's not so cut and dry. At first I was figuring for covering the 206 combined watts with solar during the day and some extra watts to charge the 2x 12v80ah batteries from the night before. It really blew my mind (if my calculations are right) that in reality it takes 800 watts of panel to do that. I mean it's just 206 watts right? In 1985 I had a 200w Roadmaster EQ in my car playing Bonjovi Lol! I was a bad ass and didn't know it with my static-matic and didn't know it was really a 800 watt ?
All jokes aside I started learning with my own research a little bit and the math I was being told to do just seamed so over board for something so small.
In my ignorance I was thinking I could just cover the total running watts per day and a little fat left to charge the two batteries and compensate (some) for a little cloud cover. For what my tests for use is I really don't use much during darkness so I would not have to put that much back in. The two batteries should give me at 50% drain 4.66 hours nightly at 206 watts being they are lead acid deep cycle. Since they run very little at night I was confident there would be extra to compensate for starting power in those 960wh. So that led me to think like a grid tied person I guess.
It seems to me the rule of thumb figures are a cover all. One size fits all but every situation isn't the same. I didn't realize solar was so iron clad. No flexibility. As in it's this or nothing which is disappointing to me if that's the case.
My calculations seems reasonable to me at least in the beginning looking into this.
400w x 4hrs = 1600 watts daily production.
So 1600w - 200w running load = 1400w left while running to charge the batteries back up.
160ah pack x .10 = 16 charge amps
80ah (used over night max) ÷ 16 = 5hrs if drained to 50%
You see in my mind I know that at least 90% of my 2.3kwh 24hr total is consumed during the day as I have ran test in many various times frames. 24hrs but also taking numbers during specific times of day as well as night. Even during peek hours to know about what they would draw during my honey spot hours for max charge capabilities.
Me also knowing 4 hours isn't the only solar I will be getting. They may not be peek performance number but there are numbers. Solar panels aren't union workers so in my mind I am thinking about the rest of the days production playing a part as well. 400whs? I have no idea yet but it's going to produce something right? Where my array will be the sun will hit them from east beginning at sunrise. From the west they will be hit with light until sunset. They will never be shaded until clouds or darkness occurs.
long story short my overnight demands are very low. That's to say 400 to 500whrs.
so long story short I figured if starting amps were covered by the battery and there are only a couple starts per day for the freezers they normally only draw the 206 watts combined. I see now that 400 watts of solar are in reality 320 per hour usable at best. So no that's probably cutting it too close. 600? Y'all would know better than I would.
I'm not looking for any more than it takes to run them during the day at this point and bank up 500 for the night. I have grid so big deal if it's cloudy the next day. One day I'd like to grow to an off grid system that never pulls from the grid with all certainty possible but that doesn't have to happen right now. I'm not miles from the grid. Far from it. I have 380amp service. I installed two 200amp panels years ago.
90 percent of my DC current knowledge come from a very long mechanic background. My A/C knowledge comes from my military MOS. 51R (interior electrician). Solar knowledge is very limited in comparison to both but knowledge of both has helped but not as much as you guys here have helped me. In my search I read MANY hours and lots of that was in forums. I'm not kissing butt by saying I chose this forum for two reasons. One being it seemed it was full of knowledgeable people willing to help others. Two people like me were treated with respect and kindness. I chose the right place. So many are ugly to the ignorant in other forums but this one, this one is a great place to learn from new friends. Those kinds of things I really appreciate in people.
I'm on somewhat of a budget since my first step was to eliminate the power hungry old appliances. That set me back nearly 600 bucks but we did down size or it would have been much higher.
I thought about doing a mini-system for each appliance but then is that cost effective? Probably not I have not really checked. Do you think so? The mini fridge only has a few condiments in it and beverages. Canned sodas and sweet tea. I drink a lot of tea lol
also it's heaviest use is from 2 or 3 until around 6 on weekdays and weekends double time because we are home all day. It's getting cooler here at night now so the overnight running should reduce quite a bit as the appliances are not in a climate controlled environment. We have pretty mild winters but in it's peek usually (freezing temps) 30 degrees are considered extremely cold but 40 to 45 is normal for overnight.
I'm contemplating getting one 100w panel, a charge controller and the inverter I'm looking at and set it up with one of my 12v80ah batteries and see really what it does since it cycles more than the freezers by a mile. Your thoughts? I can use the inverter to grow on with a larger controller later?
To me this inverter https://us.ampinvt.com/products/pur...-dc-12v-to-ac-120v-output-with-hd-lcd-display
is a prime candidate for the job but you may see an issue I do not.
If you have the time I'm grateful if you spend any of it helping me and surely want others guidance. I'm rambling but that's pretty much all I want to do. Power this lil load and charge the battery for another night of 500w use.
The way I'm thinking isn't reality I guess.
Thanks a bunch in advance and have a great day!

Ronifer said:

Indeed the numbers are low but they are what they are. I've tested with a killowatt meter and confirmed it is accurate with a friends clamp on meter. Two of the appliances are a week old and are soft start. You can barely hear them run. If I were to swap out the only old appliance in the bunch the consumption would be about 1,520kwh per day. I'm just going to build for what I now have as I just dropped $600 updating appliances already just to get the numbers down that were extremely high with a 1993 21cuft upright, a 1995 side by side fridge and a 2003 upright 15 cuft. That would have taken double of what I am looking at needing now. People don't realize just how much 20 and 30 year old inefficient appliances burn. I knew it was more but I sure didn't realize it was that much. But the numbers don't lie. And I wouldn't connect a nasty inverter to any modern appliance for long. We use the only one we have for a cheap coffee makers while camping. That's it. I can't justify in my mind knowing that my max load is 1350 watts buying a larger inverter knowing 2400 watt peek is the stated capacity of the one I am looking at. I'm 1,000 watts away from max and will be even farther after getting the 2003 replaced which I plan to do in the future after I get this hut operating on solar and get that paid for. I figured after that my system will be very ideal and dependable to stay off grid shot of inclement weather. In that case enough days of that and nobody has enough regardless. Now if I was off grid then I would opt for more array as well as battery but why should I? I have grid as well as a rather large generator. Plans B and C. The old appliances were consuming 7kwh per day. I think I can accept a .5kw grid supplement for a day or even 2.3kw should it go offline for a day. It's simply not worth it to me to buy a huge bank for a small load to run as if it's my sole means of survival which it isn't. If I have enough capacity to have these power by solar and battery 90% of a year I will be happy. Thanks for your help and guidance!

Click to expand...

Ah that’s very good to hear! I missed the part about getting soft start appliances and confirming with a clamp on meter. Then you could probably get away with a much smaller inverter. I’d consider a Victron Phoenix 12/500. Small, a bit expensive but will run your three devices like a champ unless I’ve missed something.

Tomthumb62 said:

Ah that’s very good to hear! I missed the part about getting soft start appliances and confirming with a clamp on meter. Then you could probably get away with a much smaller inverter. I’d consider a Victron Phoenix 12/500. Small, a bit expensive but will run your three devices like a champ unless I’ve missed something.

Click to expand...

I will look at it for sure. I want to buy quality that will last. I did run the meters yesterday and collected numbers again. I got from 8am which is currently when the panels will be getting first full light on them until 12:30 ( collected the data) with the sun in transit at 1pm so I guessed peak hours span to 3pm they say we get about 4 to 4.5 hours here in the winter so I collected that data. Then from 3pm to 5pm and wrote that data down. Now waiting for 5pm to 8 am results. I'm trying to figure about how much off peak storage I need. Now the dang things have flipped and used more during off peak than peak so I guess they just ain't going to follow the script lol
Thanks for your help and I will let ya know what I am looking at today. From what I am seeing during this 24hr cycle the battles I have won't make it through the night without completely draining. I need lithium batteries to carry an over nigh load like I am seeing this morning. I'm in good hands with you guys though and with y'all helping me out I am sure I will get the best set up. Have a great day!

Ronifer said:

From what I am seeing during this 24hr cycle the battles I have won't make it through the night without completely draining.

Click to expand...

That’s the rub. You usually need a much bigger battery than you think or can afford or care to spend that much money on.

So look to see if you can reduce your loads any further. For example, can you get by with one less freezer?

You can also reduce battery cost by DIY your own battery pack. Cut down by 1/3-1/2 less.

Tomthumb62 said:

That’s the rub. You usually need a much bigger battery than you think or can afford or care to spend that much money on.

So look to see if you can reduce your loads any further. For example, can you get by with one less freezer?

You can also reduce battery cost by DIY your own battery pack. Cut down by 1/3-1/2 less.

Click to expand...

Thanks Tom. Since I do have grid access the batteries aren't a huge deal but to get these off the grid completely it will take more battery as the on/off cycles seem to move around the clock. Total run time is right at 11 hours per day so I guess it's logical to say in 24 hours it advances. As in the first day of the month it's day time use of the solar and by mid month it will have shifted x number of hours. So I get why you have to have a large bank. Or set timers so they don't run as much at night. I mean they will stay frozen for 2 to 3 days unplugged if they aren't open. Not sure if I can manipulate them in that way or not. I'd rather not. I have two 12v80 ah lead acid deep cycle to get through part of a night. I think I am going to go 24v instead of 12 for this. I found some solar panels on clearance. They are 365w with a VOC of 40.1 so I am not sure if that works on 24v systems or not. I'm sure you can tell me. I read where 44.6 was the VOC and if so what would a 40.1 be for? Thanks for your help!

Ronifer said:

Thanks Tom. Since I do have grid access the batteries aren't a huge deal but to get these off the grid completely it will take more battery as the on/off cycles seem to move around the clock. Total run time is right at 11 hours per day so I guess it's logical to say in 24 hours it advances. As in the first day of the month it's day time use of the solar and by mid month it will have shifted x number of hours. So I get why you have to have a large bank. Or set timers so they don't run as much at night. I mean they will stay frozen for 2 to 3 days unplugged if they aren't open. Not sure if I can manipulate them in that way or not. I'd rather not. I have two 12v80 ah lead acid deep cycle to get through part of a night. I think I am going to go 24v instead of 12 for this. I found some solar panels on clearance. They are 365w with a VOC of 40.1 so I am not sure if that works on 24v systems or not. I'm sure you can tell me. I read where 44.6 was the VOC and if so what would a 40.1 be for? Thanks for your help!

Click to expand...

The 40.1 would be for the Vmp. (the actual max voltage to expect while under load, not open circuit, Voc) Mppt controllers have a max Voc limit. Some are 100 volts, others 150 volts or higher. Your only concern that your combined series wired voltage doesn't exceed those numbers. I would recommend you get a max 150 Voc MPPT controller and wire your panels 4s2p if you are still going with the 8 100 watt panels. or 2 in series with these higher voltage panels. Preferably 2s2p, using 4 panels.

littleharbor2 said:

The 40.1 would be for the Vmp. (the actual max voltage to expect while under load, not open circuit, Voc) Mppt controllers have a max Voc limit. Some are 100 volts, others 150 volts or higher. Your only concern that your combined series wired voltage doesn't exceed those numbers. I would recommend you get a max 150 Voc MPPT controller and wire your panels 4s2p if you are still going with the 8 100 watt panels. or 2 in series with these higher voltage panels. Preferably 2s2p, using 4 panels.

Click to expand...

The specifications shows VOC is 40.8 not 40.1 (my error)