Newb - What size do I need to run a......

[ButchDeal]

[QUOTE=littleharbor;n341522]

Window AC units are not the most efficient and 5,000 BTU is not the smallest.


Mini split units may be more efficient but unfortunately the smallest ones still pull a lot more than the 4.5 amps of a 5000 BTU window mount AC unit. I would love to find a smaller BTU sized AC unit but have never seen one. I am adding a 5000 BTU unit to a single bedroom in the Baja house. I added another 16 amps of panels to my array to help compensate for the ac unit. Being this is a 150 square foot room I could get away with a smaller than 5000 BTU unit if they actually exist.

yes but many mini split system are variable and can be limited. In any case your application is different from OPs. You have room for a larger array. OP doesn't

As for smaller units (than 5,000 BTU), a quick search found this one. https://www.ddbunlimited.com/climate...ditioners.html

[littleharbor]

Butch, If you added a link I don't see it

[Sunking]

[QUOTE=ButchDeal;n341523]

yes but many mini split system are variable and can be limited. In any case your application is different from OPs. You have room for a larger array. OP doesn't

As for smaller units (than 5,000 BTU), a quick search found this one. https://www.ddbunlimited.com/climate...ditioners.html

Used a lot of those units Butch at cell sites in outdoor cabinets. What you have not said and the OP needs to know is you are suggesting instead of buying a $200 window shaker for him to use a $4000 commercial unit. The good news is it cuts his solar cost down from $30K to $20K. From an investment POV a good call shaving $5000 off total cost. But in reality is never going to happen.

[ButchDeal]

Used a lot of those units Butch at cell sites in outdoor cabinets. What you have not said and the OP needs to know is you are suggesting instead of buying a $200 window shaker for him to use a $4000 commercial unit. The good news is it cuts his solar cost down from $30K to $20K. From an investment POV a good call shaving $5000 off total cost. But in reality is never going to happen.

yes though that was the extreme. There are units in between though, like the mini splits etc. going with the cheapest possible window unit is causing large expenses on the generation side to handle it.
As already expressed the cheapest solution is the $200 window unit and a generator. The constraint of no generator has pushed the price up.

[gendil]

easy 550watt*24 hour= 14kwatt/h (actually it was 13 and some thing)

so you need to collect 14 kwatt/hour in say 7 hours of sun that is 2000 watt solar panel that is 10*200 watt solar panels (huge system)

14000/24=600 amps(aproximat)

you need then 3 200amper 24 volt batteries to hold this amount of power


now the current in the system will be 83 amper 2000/24 = 83 amps

it is known that solar 200 watt 36 ocv volt (nominal 24 ) will produce less current... than 8.3 and higher voltage but at the the other end mppt is mppt and will draw the 200 watt (approxm) out of that panel so


since the charging voltage will be around 28 volt or so 200/28=7.2 amper *10 = 72 amper



so going with a 100 amper controller wont harm


nows your system comprise ...3 200 amper 24 volt battery....8(250 watt solar panels) 100 amper mppt solar charge controller

you have to first allow the system to charge all batteries full


then you will be use air condition 24 hour ...since your system will draw 550 out of the solar system during


charging time which will reduce our solar energy that needded to enter the battery in 7 hours of time

you can always go with 10 panels instead of 8


this will speed up your charging time and compensate for bad whether condition ...now 2500 watt panel / 26 will produce around 96 amper

now it is more safer to use 150 amper charge controller


charging current of 100 amper is 1/6 batteries amper capacity ................. for agm you even can go on c/4 which is 600/4=150


so you still in the safe side

final calculations 10 *250 watt (nominal 24)+150 amper charge controller ...+600 amper 24 volt battery agm


plus the necessary fuse and protection circuit and mountings and you are there with an air condition 24 hours
)

[Sunking]

easy 550watt*24 hour= 14kwatt/h (actually it was 13 and some thing)

so you need to collect 14 kwatt/hour in say 7 hours of sun that is 2000 watt solar panel that is 10*200 watt solar panels (huge system)

14000/24=600 amps(aproximat)

Wrong.

If you use 14 Kwh per day requires the panels to generate 21 Kwh. Secondly very few places on Earth get 7 Sun Hours, and no place on earth gets 7 Sun Hours over a period of 50 days.

[gendil]

sorry but the problem is that i make my calculations based on the "sunny land" libya

i correct you sir ....we do have strong sun 8 hours in winter and we do have 12 hour of sun in the summer continous with no rains and no stroms

[gendil]

Wrong.

If you use 14 Kwh per day requires the panels to generate 21 Kwh. Secondly very few places on Earth get 7 Sun Hours, and no place on earth gets 7 Sun Hours over a period of 50 days.

sorry but the problem is that i make my calculations based on the "sunny land" libya

i correct you sir ....we do have strong sun 8 hours in winter and we do have 12 hour of sun in the summer continous with no rains and no stroms

[SunEagle]

sorry but the problem is that i make my calculations based on the "sunny land" libya

i correct you sir ....we do have strong sun 8 hours in winter and we do have 12 hour of sun in the summer continous with no rains and no stroms

I understand your location provides more sun than just about any where else on earth so while you are lucky you should at least buffer your information making the claim of where you are and for most others there will be less useful sunlight to generate power from a pv system.

I have no problem with you providing input but please try to remember that what works for you will not work for a lot of other people.

[gendil]

I understand your location provides more sun than just about any where else on earth so while you are lucky you should at least buffer your information making the claim of where you are and for most others there will be less useful sunlight to generate power from a pv system.

I have no problem with you providing input but please try to remember that what works for you will not work for a lot of other people.

yes it was a minor mistake ....i just make calculation immediately and forget to ask the man where on earth he wanted to harvest sun power ...it really makes difference

thanks

[SunEagle]

yes it was a minor mistake ....i just make calculation immediately and forget to ask the man where on earth he wanted to harvest sun power ...it really makes difference

thanks

Especially when we have people wanting to go off grid up North where the sunshine is really short compared to Florida where I live and a lot less then the South-West of the US.

I appreciate you understanding why we try to present good information and not something that get people excited only to find out the real cost of going off grid.

[adoublee]

this is for vegetable storage at a produce stand. I need to hold at about 45 degrees

Is the cooler even needed in the winter when sun hours are lower? Have you said where you are located? At night do you leave the trailer at the stand or can you move it to a location where grid can run the cooling overnight and cooling is offgrid only during the day?

[SDaniels]

It is located in WIsconsin, USA. It will be used from about July 1 - Aug 31ish.... The trailer will sit day and night at location. I don't see running it at night, since it should stay cold enough overnight to hold reasonable temps for purpose. I was thinking about putting a timer on it to be off from 8:00 pm to 8:00 am. I am looking into low power AC units that basically stay on all the time, but slow down. Basically one startup per day. Running amps after start up is approx 5 Amp at 110 VAC. Even looking at a soft start component that will cut the starting amps in half.

Right now we travel to site and "teardown" meaning we pack all the leftover produce, scales, baskets etc... and bring home to our walk in cooler. We are looking to have the employee, pack everything into this trailer at the end of the day. Not that it is a big deal to move leftovers and mics, but it is wear and tear, and we lose product. It would also be used to have extra product in so we're not wasting it in the sun. We would open it in the morning, take out needed product, restock it with enough for the day and possibly extra, employee may go in it once or twice to grab restock product.
I have about 80 sq ft of roof space sloped.
Really do not want to use more carbon as we try to be as responsible as possible.

Here is a question. how many operating amps both AC or DC are realistic out of say a 400 watt array? I am drumming up a crazy plan that might be an alternative. Still digging, but I would really like to make a standard AC unit work.

[ButchDeal]

how many operating amps both AC or DC are realistic out of say a 400 watt array?

forget using 100watt modules. Use instead non 12V residential modules rated at 250watts or more each.
These modules are far cheaper per watt and you are going to need more than 400 watts. You would likely need at least 1000 watts (1kw) on a decent day just to run the 5 amp AC unit though more would be better to handle some battery charging and cloudy days.
You are going to need a generator no matter what for the very cloudy days and some battery maintenance.

If you go with 24 or 48V battery bank and a decent inverter you shouldn't need any soft start components.

[PNPmacnab]

I run with a minimal battery system that is used primarily for motor starting. As an example, a 120W fridge draws about 120A at 12V at starting before it drops to 9A running. Panels provide real time power. The system has to be smart, really smart. When it senses the battery even dropping a little, it shuts off. When sunlight is abundant, it lowers temps to store for later. Otherwise it chooses a higher temperature. External temperature sensor is used to refrigeration can be turned totally off, no fan circulation. If you personally can't make that system, you have to go big, dumb and expensive. Also need to accept some days it just won't work. Don't even think of 12V. I would use 48V.