Simple system but I need help with it.

[Vigo]

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.

 

[Tomthumb62]

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

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.

 

[Whats-n-Watts]

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.

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!

 

[Whats-n-Watts]

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.

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!

 

[Tomthumb62]

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!

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.

 

[Whats-n-Watts]

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.

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!

 

[Tomthumb62]

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

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.

 

[Whats-n-Watts]

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.

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!

 

[littleharbor2]

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!

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.

 

[Whats-n-Watts]

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.

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

 

[littleharbor2]

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

OK, I see. The Vmp is only 34 volts. Much easier to series wire and keep within Voc. limits for the inverter or controller.

 

[Whats-n-Watts]

Having "a just enough perfect sized system" isn't big enough

I have found out your statement is written in some solar guru scroll somewhere and it's a fact.

 

[Tomthumb62]

I have found out your statement is written in some solar guru scroll somewhere and it's a fact.

Well if it’sa perfect sized system in summer, it’s sure as heck not big enough for winter! You can’t think perfect for now but perfect for all seasons.

 

[Whats-n-Watts]

Well if it’sa perfect sized system in summer, it’s sure as heck not big enough for winter! You can’t think perfect for now but perfect for all seasons.

Exactly ?

 

[ksmithaz1]

I can say that even my oldest refrigerator (a 15yro Frigidaire) barely tweaks anything at startup. The newer Haier (Maybe 7yro) counter depth is even better. You can't even hear it when it's running. Neither use enough power to even notice on my graphs.

That being said... I'd put one of the 48v/3KW AIO units in just for simplicity. ~$500. I'd go ahead and put in a single rackmount LiPO4 5KWH ~$1500 and maybe 4-6 used 300W panels (~600) shoot for 1500W. I'd wire up to a small panel, put each appliance on a separate 15a breaker, and then run a couple of convenience outlets and a lighting circuit. If you do it yourself you'd spend maybe $3K all in, but you'd have access to adequate power for other use (like lighting, lightweight power tools, etc).

Yes, you can probably get by for ~$1000 but people tend to forget about the cost of the effort. Your going to spend a week screwing around getting it all going, then sit around worrying if your deep freeze is going to crap out because you undersized something. Plus if you have ~2KW usable out at your shed, I'm SURE you will have another project that can make use of it. If I was going to trim costs, I'd Home brew less battery, then cut down the panels. But I'd plumb for 8 panels, and more battery.

 

[ksmithaz1]

I can say that even my oldest refrigerator (a 15yro Frigidaire) barely tweaks anything at startup. The newer Haier (Maybe 7yro) counter depth is even better. You can't even hear it when it's running. Neither use enough power to even notice on my graphs.

That being said... I'd put one of the 48v/3KW AIO units in just for simplicity. ~$500. I'd go ahead and put in a single rackmount LiPO4 5KWH ~$1500 and maybe 4-6 used 300W panels (~600) shoot for 1500W. I'd wire up to a small panel, put each appliance on a separate 15a breaker, and then run a couple of convenience outlets and a lighting circuit. If you do it yourself you'd spend maybe $3K all in, but you'd have access to adequate power for other use (like lighting, lightweight power tools, etc).

Yes, you can probably get by for ~$1000 but people tend to forget about the cost of the effort. Your going to spend a week screwing around getting it all going, then sit around worrying if your deep freeze is going to crap out because you undersized something. Plus if you have ~2KW usable out at your shed, I'm SURE you will have another project that can make use of it. If I was going to trim costs, I'd Home brew less battery, then cut down the panels. But I'd plumb for 8 panels, and more battery.

You could grab 4 FLA's / GEL Cells and 2-3 used panels to kick-start, and keep the project closer to $1000. The inverters do have a leech current ~ 50W.

 

[Whats-n-Watts]

I can say that even my oldest refrigerator (a 15yro Frigidaire) barely tweaks anything at startup. The newer Haier (Maybe 7yro) counter depth is even better. You can't even hear it when it's running. Neither use enough power to even notice on my graphs.

That being said... I'd put one of the 48v/3KW AIO units in just for simplicity. ~$500. I'd go ahead and put in a single rackmount LiPO4 5KWH ~$1500 and maybe 4-6 used 300W panels (~600) shoot for 1500W. I'd wire up to a small panel, put each appliance on a separate 15a breaker, and then run a couple of convenience outlets and a lighting circuit. If you do it yourself you'd spend maybe $3K all in, but you'd have access to adequate power for other use (like lighting, lightweight power tools, etc).

Yes, you can probably get by for ~$1000 but people tend to forget about the cost of the effort. Your going to spend a week screwing around getting it all going, then sit around worrying if your deep freeze is going to crap out because you undersized something. Plus if you have ~2KW usable out at your shed, I'm SURE you will have another project that can make use of it. If I was going to trim costs, I'd Home brew less battery, then cut down the panels. But I'd plumb for 8 panels, and more battery.

In the last 37.5 hours they have collectively consumed 2,890 watts or around 77w per hour. The highest I recorded was 2,310w but it has been cooler since then. I have a 20x30 shop so the shed's soul purpose is housing these appliances and canned goods so really no additional power needed. Single 15w led light for maybe 10 mins on occasion. I have grid service so no worries about being down at all. We go without power here sometimes for a week after a hurricane so nothing we don't deal with during hurricane season. Also it takes at least 2 days for them to even think about thawing as long as nobody opens them. The shed has 220v @50 amps to it now. Small sub panel 15a breakers. At best I figure on the hot summer days they may consume up to 2,500 watts in 24hrs. Where I will be installing my panels (ground mounted) it's full sun from 10am until 5 pm. Zero shading. I'm figuring 600 watts of panel should do it. I found a Power AIO inverter 24v 3000w that should be more than enough. My current surge watts are reading just over half of that 3000w continuous load rating so it's already over kill IMO. I'm considering going ahead and updating the 2003 upright as it's the largest draw. The new chest freezer uses 1/2 the electricity so that would reduce numbers by no less than 400+ watts per day so I think dropping another $350 for the final upgrade will be worth it in the long run because I won't need as much solar to buy and maintain. Thanks for your help!

 

[Whats-n-Watts]

Happy Saturday to all. I finally got enough data to place and order for goodies. My summer watts were obviously higher for the units since they aren't climate controlled. Coming in at 100w per hour vs 77w per hour and it hasn't been as cold as it will get into the winter. After recording off-peak draws a 12v100ah can carry them through the night even in summer temps. They are barely running at all at night now if at all.
I know this set up will seem ignorant but I'm on a budget and I would really like to see these things on solar so here goes. I took everything all that gave me input into consideration.
I finally decided on a 2500w/5000w stand alone inverter powered by a 12v100ah Lifepo4 battery getting its juice from 3x300 watt Werchtay panels. Each panel on its own 30 amp MTTP charge controller in parallel. The 900 watt array should under idea conditions give me 2880 watts in 4 hours of peak sun. Right now they are maxed out at 1,850w per day consumption but that will change to 2,310w come summer.
I understand this may be an unorthodox method but it was one that gave me the best bang for my buck.
I know that I need other stuff such as cut offs, fuses etc but I am not sure what to get or where to put it in terms of a proper wiring job goes. Another thing I am not sure of is cable size from my panels as the perfect spot for them is a total of 40 foot from connectors to controllers. I did some reading and it looks like maybe 6 or 8 awg. A pic of panel data is attached. Y'all would know wayyyy better than me. I know the closer the better but I can't exactly move the building.
Any suggestions are welcomed! Thanks guys y'all rock!

 

[Whats-n-Watts]

@Hogheavenfarm @Zapper77 @Q-Dog @400bird
Any suggestions guys?

 

[Q-Dog]

Why do you want 3 charge controllers? I like redundancy, but within reason. A Victron 150/60 would run 3 of those panels in series, which would let you run off-the-shelf 10awg solar extension cables from the panels to the controller.