Supply for 60 amp shore power connection

Lumisol

I am just starting on this solar off grid power adventure and have only a tiny bit of knowledge on how to set up a system and need all the help and advice I can get.

I was wondering about setting up a small PV system for my trailer that has a 60 amp shore power connection cord( the electrical panel is set up for 45 amps total power). Would it be a good choice to set up 4 285 watt panels with 8x 6 volt 225 ah batteries wired for 12 volts at 900 amp hours to supply the power for the shore power cord to plug into?
Would 6 batteries producing 675 ah at 12 volts be enough to use a 3000 watt A/C(only during the day hours), a 80 watt refrigerator(low use), a 750 watt microwave (around 15 minutes a day) and an 30 watt TV (for 3 or 4 hours in the evening)? The lighting is all on the 12 volt side of the panel and is all using LED bulbs at 1 watt each 10 or 12 watts worth of light on at a time at most, more often 4 or 5 watts and for only a couple of hours a night..
Will the 6 batteries be sufficient and will the 4 panels be enough to charge them daily? The system will be in Show Low and get about 5.5 to 6 hours of sun a day that will produce power.
We use the RV for a week at a time at the longest and more often a couple days to 4 days in a row. Then it will be empty with only the refrigerator running on a lowest setting, no lights, no A?C and no TV.

I was considering AGM (Absorbent Glass Mat) batteries so that they will not need to be topped off or maintained physically and will be more resistant to colder weather in the winter months.
Does it make sense to use the shore power connector to provide power to the panel and be able to also use the circuit breakers it provides as well as the ones I install on the charge controller / inverter board?
What am I missing and what else do I need to consider?

dennis461

 if you have 4 panels. 285 watts each, the most you will ever get is 1,140 watts,
You cannot run a 3000 watt AC unit, right?

mcgivor

dennis461 said:

 if you have 4 panels. 285 watts each, the most you will ever get is 1,140 watts,
You cannot run a 3000 watt AC unit, right?

The 1140 watts is theoretical, the actual would more than likely be in the 800 watt range, with reasonable mounting and good sun, without shading. 
The best place to start is with an accurate audit of loads over time, using a device such as a Kill-a-watt to determine actual figures, select an inverter to support the loads, include the inverter self consumption to overall loads, size the battery to loads, then determine the array required.
Being this is not a full time use off grid use, it's stated how long it's used but not how often, has to be taken into consideration.

littleharbor2

If you want to connect the shore power line to the inverter you must disconnect the converter so it doesn't try to charge the batteries off of themselves.

jonr

You can run a 3000 watt AC off of batteries charged by 1140W of solar panels.  Just not for very long.  Consider running a generator whenever you need AC.

Maintaining a refrigerator with solar power is reasonable.

Estragon

Also, 3kw is ~250a at 12v. Deep cycle batteries are normally rated at a 20hr discharge rate. Capacity will be substantially lower discharging at around a 3hr rate, and having 3-4 strings in parallel won't help.

Lumisol

mcgivor said:

dennis461 said:

 if you have 4 panels. 285 watts each, the most you will ever get is 1,140 watts,
You cannot run a 3000 watt AC unit, right?

The 1140 watts is theoretical, the actual would more than likely be in the 800 watt range, with reasonable mounting and good sun, without shading. 
The best place to start is with an accurate audit of loads over time, using a device such as a Kill-a-watt to determine actual figures, select an inverter to support the loads, include the inverter self consumption to overall loads, size the battery to loads, then determine the array required.
Being this is not a full time use off grid use, it's stated how long it's used but not how often, has to be taken into consideration.

Wouldn't I need to get the power there first to do an audit of electricity used?
We use it once a month or so, sometimes once every couple of months.
This is the AC:  https://www.amazon.com/gp/product/B01DREGOI2/ref=ox_sc_sfl_title_1?ie=UTF8&psc=1&smid=A36WDAL3PT7DON
And these batteries: https://www.amazon.com/gp/product/B009MOY2JK/ref=ox_sc_sfl_title_2?ie=UTF8&psc=1&smid=A3H30ATSR61H8N
The rest (actually all ) is yet to be determined. I have access to 285 watt panels in unlimited quantities.
Charge controller and inverter will be sized the what other components I buy. 
Is there more info you need?

Lumisol

littleharbor2 said:

If you want to connect the shore power line to the inverter you must disconnect the converter so it doesn't try to charge the batteries off of themselves.

I will not be connecting the batteries to the RV battery connection, that will be unused. Do I still need to disconnect the converter without any load?

Lumisol

dennis461 said:

 if you have 4 panels. 285 watts each, the most you will ever get is 1,140 watts,
You cannot run a 3000 watt AC unit, right?
Is it not possible to run off the battery's power and then recharge the batteries from the array?
The AC cycles on and off, it's mostly off in the climate there I would think. I cannot check that without having the AC and power first though. With an outside temp of 80 and inside set to 75 it shouldn't have to do a lot of work.

mcgivor

Basically it's the AC unit that determines the size of the system, driving it from  modest to large, despite the limited useage during the daylight hours, the infrastructure still needs to be sized to support it, the ability to charge the battery and run the unit simultaneously. In other words you need to charge the battery without taking large withdrawals from the bank whilst attempting to charge it, therefore the array needs to at least be large enough to support all loads and charge the battery,  by rough calculation you wold need around 4.5Kw or 21 of the 285 watt panels assuming 75% efficiency, without considering other losses, whist slil allowing charging . Air conditioning is not as simple as it appears, consider a fan or evaporation cooler, your temperatures are so low it seems a great expense for little gain. 

My recommendation is stay away from 12V and choose 24 or 48V, less or no parallel batteries, smaller cables and protective devices. Without the air conditioning everything looks doable, depending upon location, you are unlikely to get 5 to 6 hours of usable sunlight per day, so to allow a more accurate calculation location is an important piece of the puzzle.
My opinions, others may differ.

https://www.sylvane.com/swamp-cooler-buying-tips.html

Photowhit

You need to calculate the load the best you can, a 3000 watt A/C in a hot environment, might have a 100% duty cycle the first hour and then a 60% or better there after. So for the sake of expediting this I'll say 3000 watt hours for the first hour and 5000 watt hours for the next 3 hours. That's 8000 watt hours, on a 24 volt system that would be 333 amps, for a battery to run the A/C for the first 4 hours, depleting only to 50%, You would need a 665 Amp hour 24 volt battery bank. I have one it weights 1100 lbs!

Lumisol

mcgivor said:

Basically it's the AC unit that determines the size of the system, driving it from  modest to large, despite the limited useage during the daylight hours, the infrastructure still needs to be sized to support it, the ability to charge the battery and run the unit simultaneously. In other words you need to charge the battery without taking large withdrawals from the bank whilst attempting to charge it, therefore the array needs to at least be large enough to support all loads and charge the battery,  by rough calculation you wold need around 4.5Kw or 21 of the 285 watt panels assuming 75% efficiency, without considering other losses, whist slil allowing charging . Air conditioning is not as simple as it appears, consider a fan or evaporation cooler, your temperatures are so low it seems a great expense for little gain. 

My recommendation is stay away from 12V and choose 24 or 48V, less or no parallel batteries, smaller cables and protective devices. Without the air conditioning everything looks doable, depending upon location, you are unlikely to get 5 to 6 hours of usable sunlight per day, so to allow a more accurate calculation location is an important piece of the puzzle.
My opinions, others may differ.

https://www.sylvane.com/swamp-cooler-buying-tips.html

Did you look at the AC unit I had chosen? It only draws 11.5 amp at 110 volts. The space being cooled is 21 feet by 8.5 feet. 
Are you sure about the power needed?

Lumisol

Photowhit said:

You need to calculate the load the best you can, a 3000 watt A/C in a hot environment, might have a 100% duty cycle the first hour and then a 60% or better there after. So for the sake of expediting this I'll say 3000 watt hours for the first hour and 5000 watt hours for the next 3 hours. That's 8000 watt hours, on a 24 volt system that would be 333 amps, for a battery to run the A/C for the first 4 hours, depleting only to 50%, You would need a 665 Amp hour 24 volt battery bank. I have one it weights 1100 lbs!

The AC draws 11.5 amps at 110 volts when operating. I would start it while the inside temp is still around 70 degrees and it would only need to maintain that temp for 5 hours or so and then be shut off and the windows opened up again as the outside temps drop back to the 70's again. The overnight temps are in the upper 50's and low 60's.
I have no problem adding batteries and panels if it is actually needed, but I think you are over estimating based on the 3000 watts that I mentioned, I think that figure is incorrect as it is 11.5 amps at 110 volts. Even using a single phase power factor of .5 (halfway between full inductive and full resistive loads) it is only 635 watts needed. Even though one seller claimed 3000 watts draw, the calculations do not substantiate that amount. Is it possible that they meant to put down 300 watts and accidentally added an extra zero for 3000 watts?Does anyone know the true power factor for an AC unit?

Thanks to everyone that is helping me on this project, your input is extremely valuable to me.

Photowhit

"...11.5 amps at 110 volts" is NOT 3000 watts.

Calculation only as good as the information given.

The space being cooled is only one factor, will it be in the shade? Is it well insulated?

I setup a cabin 10x16 with 6" thick walls built in the shade, all so I could air condition on a minimal system. with 1000 watts of panels and 4 golf cart batteries, I could run the air for 4-5 hours a night. My air conditioner was 5300 btu (the one you are looking at is 13.5K btu's) I added panels to give me more daytime running of the air conditioner. This was a 24 volt system, I would suggest if loads will be above 1000 watts, you should seriously consider a higher voltage system.

mcgivor

Lumisol said:

mcgivor said:

Basically it's the AC unit that determines the size of the system, driving it from  modest to large, despite the limited useage during the daylight hours, the infrastructure still needs to be sized to support it, the ability to charge the battery and run the unit simultaneously. In other words you need to charge the battery without taking large withdrawals from the bank whilst attempting to charge it, therefore the array needs to at least be large enough to support all loads and charge the battery,  by rough calculation you wold need around 4.5Kw or 21 of the 285 watt panels assuming 75% efficiency, without considering other losses, whist slil allowing charging . Air conditioning is not as simple as it appears, consider a fan or evaporation cooler, your temperatures are so low it seems a great expense for little gain. 

My recommendation is stay away from 12V and choose 24 or 48V, less or no parallel batteries, smaller cables and protective devices. Without the air conditioning everything looks doable, depending upon location, you are unlikely to get 5 to 6 hours of usable sunlight per day, so to allow a more accurate calculation location is an important piece of the puzzle.
My opinions, others may differ.

https://www.sylvane.com/swamp-cooler-buying-tips.html

Did you look at the AC unit I had chosen? It only draws 11.5 amp at 110 volts. The space being cooled is 21 feet by 8.5 feet. 
Are you sure about the power needed?

Actually I did look at the Amazon page but there was no mention of consumption, checked again and saw the question section, where the 11.5A answer appears. This somewhat changes things being 1300 watts, but doesn't make it easy, please read the information in the attached link for more insight. By the way you are lucky to have such mild temperatures, I have to deal with 116°F high and 85°F lows, at times, without air conditioning , primarily because I'm off grid and the expense of building a system is cost prohibitive. The best inverter mini split I've found is 2.3A at 230V for a 8000-14000 BTU unit, but the evaporation cooler gets me by, consuming 39 watts, for now at least. Anything is possible, your proposition is not totally without merit , just think you should know what it is you are getting into, before dealing with details.
http://www.technomadia.com/2015/02/the-almost-fantasy-of-solar-powered-rv-air-conditioning/

Lumisol

It looks doable with lithium batteries and a softstart for the AC then, assuming I choose to go that route. I also took a look at the evap coolers (thanks for the suggestion, McGivor) on Amazon and they have some interesting units available there. I grew up with evap cooling in Phoenix as a kid and remember that it worked great from May to September when the monsoons would start it got a little bit sticky because of the extra humidity. I am thinking of an evap for the dry months and an AC for only the last month of use in the White mountains. We may even be ok without any AC there at all and just go with an evap exclusively.
So do you think the other items mentioned will be fine with 4 or 5 285 watt panels and 8 6 volt batteries tied to an inverter supplying the power through the shore power connector wired to the inverter?
The panel says it's made for 45 amps of power to be supplied, but the connector is a 60 amp cord and plug. My question is: should I supply 60 amps at 110 volts to the connector or just the 45 amps the panel is rated at?

mcgivor

@lumisol said:  So do you think the other items mentioned will be fine with 4 or 5 285 watt panels and 8 6 volt batteries tied to an inverter supplying the power through the shore power connector wired to the inverter?

The panel says it's made for 45 amps of power to be supplied, but the connector is a 60 amp cord and plug. My question is: should I supply 60 amps at 110 volts to the connector or just the 45 amps the panel is rated at?

Did a rough calculation using the loads stated and time used, even went with 50% duty cycle for the refrigerator and 2 days of battery reserve, it would seem to me that  you must have done the calculation yourself, because it's pretty accurate.The inverter figures used were for a Cotek 1500W PSW, have manual handy, 3000w is probably overkill for your loads, didn't factor in the sleep mode either, . Best if you put all 8 batteries in a single string for 48V see post#10, easy to expand in the future, if needed,  get a charge controller with a little more current capacity than currently needed, say a 45-60A. 

With regards to the shore cable, there should be no problem doing as planned, since at 45A, it's rated above what even a 3000W inverter can put out, is the panel a 120/240 volt ? and what inverter are you considering ? A simple jumper may be required depending on panel and inverter,  

Lumisol

mcgivor said:

@lumisol said:  So do you think the other items mentioned will be fine with 4 or 5 285 watt panels and 8 6 volt batteries tied to an inverter supplying the power through the shore power connector wired to the inverter?

The panel says it's made for 45 amps of power to be supplied, but the connector is a 60 amp cord and plug. My question is: should I supply 60 amps at 110 volts to the connector or just the 45 amps the panel is rated at?

Did a rough calculation using the loads stated and time used, even went with 50% duty cycle for the refrigerator and 2 days of battery reserve, it would seem to me that  you must have done the calculation yourself, because it's pretty accurate.The inverter figures used were for a Cotek 1500W PSW, have manual handy, 3000w is probably overkill for your loads, didn't factor in the sleep mode either, . Best if you put all 8 batteries in a single string for 48V see post#10, easy to expand in the future, if needed,  get a charge controller with a little more current capacity than currently needed, say a 45-60A. 

With regards to the shore cable, there should be no problem doing as planned, since at 45A, it's rated above what even a 3000W inverter can put out, is the panel a 120/240 volt ? and what inverter are you considering ? A simple jumper may be required depending on panel and inverter,  

I am not sure, but I think it's just a 110 volt ac system. 
Will 6 batteries last us for a weekend every other week or so, or do I need 8?
Do you recommend 4 panels at 285 watts or 5?
What inverter do you recommend? I was thinking pure sine wave for the TV and microwave oven compatibility. Not sure what size to get though frankly. 5000 watt? Is a modified sine good enough for the tv and microwave to run off of?
I guess 48 volt will yeild the best solution for the battery pack and last us the longest so that's a good idea. for 48 volt I need all 8 batteries and 36 volt isn't a good idea.

Lumisol

https://www.amazon.com/5000W-Power-Inverter-10000w-220VAC/dp/B00VAD68AM/ref=sr_1_10?ie=UTF8&qid=1490729829&sr=8-10&keywords=5000+watt+inverter+pure+sine++48+volt

Is this a decent inverter?

Or there is this one:  https://www.amazon.com/dp/B00O805FO4/ref=pd_luc_rh_sbs_01_01_t_img_lh?_encoding=UTF8&psc=1&dpSrc=huc&preST=_SY300_QL70_&dpID=412Wnkmx3+L

Which is a better unit and why?

Also is there a good charge controller that you recommend? https://www.amazon.com/Solar-Controller-Monitor-Temp-Sensor-ZHC/dp/B06XNP1BGR/ref=sr_1_10?ie=UTF8&qid=1490731683&sr=8-10&keywords=charge+controller+monitor

or this: https://www.amazon.com/gp/product/B00E7NI9PE/ref=ox_sc_sfl_title_6?ie=UTF8&psc=1&smid=ATVPDKIKX0DER and this https://www.amazon.com/gp/product/B00ECVWDGC/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A3VAEX6T4LXLDZ
What other components will I need? A disconnect switch or panel? what type is best? what fuses are needed? Is it a good idea to use a monitor to keep an eye on things and what is needed for that?

So many questions.
If you think of any questions I missed, answer those to please

Thanks for all the help on this.

Photowhit

There is not enough info about the first inverter and the second says "Aims" enough info that I would run away. Look through this list for some quality inverters;

https://www.solar-electric.com/residential/inverters/off-grid-inverters.html?nav_inv_input_voltage=48+Volts

Also you appear to be getting more and more out of balance than pulling into balance this system. In general, quit talking about how many batteries rather talk about how many Kwh's of storage. If you have 8 - 6v -225ah batteries, you will have about 8x (6v x 225ah)= 10.8 Kwh of storage. A 5000 watt inverter can use more than half of that in an hour! Batteries are rated at a 20 hr discharge rate, at a rate of 2 hr they will have seriously reduced capacity.

An "every other week" would pretty much be the same as living around the clock, the system will have no time to recover, so plan on running the generator often.

As a load a fridge left in a hot trailer will want over 1Kwh per day to run, much of that stored energy at night. Your panels if 5 at 285 watts, will produce about 5 x 285 = 1425 watts x .75 (for normal conditions) = 1068 watts per average hour of sun light...

Lumisol

Photowhit said:

There is not enough info about the first inverter and the second says "Aims" enough info that I would run away. Look through this list for some quality inverters;

https://www.solar-electric.com/residential/inverters/off-grid-inverters.html?nav_inv_input_voltage=48+Volts

Also you appear to be getting more and more out of balance than pulling into balance this system. In general, quit talking about how many batteries rather talk about how many Kwh's of storage. If you have 8 - 6v -225ah batteries, you will have about 8x (6v x 225ah)= 10.8 Kwh of storage. A 5000 watt inverter can use more than half of that in an hour! Batteries are rated at a 20 hr discharge rate, at a rate of 2 hr they will have seriously reduced capacity.

An "every other week" would pretty much be the same as living around the clock, the system will have no time to recover, so plan on running the generator often.

As a load a fridge left in a hot trailer will want over 1Kwh per day to run, much of that stored energy at night. Your panels if 5 at 285 watts, will produce about 5 x 285 = 1425 watts x .75 (for normal conditions) = 1068 watts per average hour of sun light...

To be honest there is no system yet at all, that's why I need answers to those questions I asked.
I talk about the number of batteries because the amp hours and volts has already been stated and will not change, the only variable left is the number of them so that is why it is relevant to me.

This is not enough information? What else do you need to know, I can ask the manufacturer...
Why are you afraid of the second one?
The fridge is 80 watts when running and only runs a couple hours a day. How is that 1 kwh? It looks more like 160 to 240 wh to me unless I am missing something. The temps inside the RV will be only around 75 degrees and the fridge is getting a lot of extra insulation in the installation of it. It is only 3.2 CF.
Do you have any inverters that are on Amazon? I prefer to buy from them for the free shipping, and ease of returns.
Does the inverter use up the power even without a load on it? And will it use up 10 kwh of power in one hour? That seems a little excessive. Do I need to have 5 panels just to run the inverter and then 5 more for any load on it?
You think that charging the batteries for 14 days will not have time to recover from using it for 2 days?
What about 10 panels? 20? 40? How many does it take to charge the batteries?

How many batteries (WH) are needed to run a 750 watt microwave for 10 minutes and a tv and fridge for 4 or 5 hours each pulling 80 watts a piece? The lights are all led at 1 watt each and will only have a couple at a time running and only for a couple hours. The system will then have 14 to 30 days to recover.

My neighbor across the street works at a company that has a solar power branch, (they installed the largest off grid solar system in AZ and the Buckeye Hills Shooting Park and the Phoenix Convention Center (the largest system in downtown Phoenix)) maybe he can give me some parts at cost, what do I need in a charge controller and inverter?

What generator should I plan on running? I have been using the RV there for 3 years without any generator yet. (I have been using flashlight AA batteries to power the lights) I change them once a year.

Thanks for the help, I have a lot more questions now after reading your comment.

Photowhit

If it will only get to 75, you don't need an Air conditioner.

Lumisol said:

Photowhit said:
An "every other week" would pretty much be the same as living around the clock, the system will have no time to recover, so plan on running the generator often.

You think that charging the batteries for 14 days will not have time to recover from using it for 2 days?

When I put something in quotes, I'm usually quoting YOU! When I define my statement with your words, please read it.

Lumisol said:

How many batteries (WH) are needed to run a 750 watt microwave for 10 minutes and a tv and fridge for 4 or 5 hours each pulling 80 watts a piece? The lights are all led at 1 watt each and will only have a couple at a time running and only for a couple hours. The system will then have 14 to 30 days to recover.

Tired of having undefined loads, if this is how you want to define them use it and figure it out. I don't want to play.

BB.

A "typical" efficient 120 VAC refrigerator freezer uses around 1,000 to 1,500 WH per day (depending on specific model, size, weather, how clean the coils are, age, how often you open the door, freezing ice cubes, etc.)... Usually around 120 Watts and 50% duty cycle (120w * 0.50 * 24 hours per day = 1,440 WH per day). Note--Starting surge for an induction motor capacitor can be as high as 5x running power (i.e., 600 VA starting surge). Also a frost free fridge/freezer has a ~600 Watt evaporator defrost heater). Nominally, a 1,200 to 1,500 Watt AC inverter minimum is good for running a full size energy start fridge + lighting, RV water pump, laptop, etc..

And there are other options. Get a 7-10 cuft chest freezer and an external thermostat. Still a 120 Watt compressor, but ~250 WH per day (0.25 kWH per day). And still need a ~1,200 to 1,500 Watt AC inverter minimum.

Or, there are DC compressor fridge/freezers--As a fridge, they can run near 250 WH per day too (and no AC inverter)--However, DC refrigerator/freezers are typically quite expensive--Over all, they may not save you much money.

Note that AC inverters do use energy just to turn on. A 300 Watt unit may use 6 Watts. A 5,000 Watt unit may use 20-40 Watts or more (40 watts * 24 hours per day = 960 WH per day--Almost as much as a fridge).

With flooded cell lead acid batteries (the least expensive, and fairly forgiving, but require maintenance), there are two criteria that set the size of the battery bank (AH and voltage).

First is--Usually the optimum price/performance battery bank is 2 days of storage and 50% maximum discharge (or 4x daily load) (1-3 days of storage is the typical min/max range).

The second is sizing the battery bank to support your peak loads. A lead acid battery bank is typically sized for 20 hour discharge rate (5 hours per night, 2 nights, 50% maximum discharge). The maximum continuous current is typically an 8 hour discharge rate (remember that the apparent capacity of a battery drops the faster you discharge it--But these numbers are close enough for us at the moment).

And the fastest you would discharge the battery bank would be a few minutes to an hour so at a 5 hour discharge rate. And for a few seconds of surge, 2.5 hour discharge rate. There are other battery chemistries that have higher surge current, but cost more, and have "other issues" that need to be addressed.

In general, you want to pick as small as loads as you can--It it almost always cheaper to conserve energy than it is to generate the energy.

Roughly, 1,000 WH (1 kWH) per day--Good for a cabin with LED lights, RV water pump, cell charger, laptop computer.

3,300 WH per day--Add refrigerator, well pump, washing machine, LED TV... Basically a near normal electrical life for a very efficient off grid home.

Get up to 10,000 WH per day--300 kWH per month--A relatively efficient on-grid home. And a very large for an off grid power system.

While you pay around $0.10 to $0.30 per kWH (North American) for utility power--It is very easy to spend $1.00 to $2.00+ per kWH for off grid power (one member here has his off grid power down towards $0.50 per kWH--But that takes work).

For lower cost AC inverter, Cotek and Samlex (same mfg., different sales channels?) would be a place to start.

In any case, define your loads first, then design a system to support the loads.

An alternative, if you have limitations (space for batteries, space for panels, how much you want to spend, etc.)--We can figure out a system that will (hopefully) meet the limitations but still support your loads.

Of grid solar is not cheap.

-Bill

Lumisol

Photowhit said:

If it will only get to 75, you don't need an Air conditioner.

Lumisol said:

Photowhit said:
An "every other week" would pretty much be the same as living around the clock, the system will have no time to recover, so plan on running the generator often.

You think that charging the batteries for 14 days will not have time to recover from using it for 2 days?

When I put something in quotes, I'm usually quoting YOU! When I define my statement with your words, please read it.

Lumisol said:

How many batteries (WH) are needed to run a 750 watt microwave for 10 minutes and a tv and fridge for 4 or 5 hours each pulling 80 watts a piece? The lights are all led at 1 watt each and will only have a couple at a time running and only for a couple hours. The system will then have 14 to 30 days to recover.

Tired of having undefined loads, if this is how you want to define them use it and figure it out. I don't want to play.

I don't even need power there. We have been using it for 3 years without any power other than flashlight batteries for the lighting.
I am doing this because I want to, not because I need to.

I mentioned the loads in the first post, I guess you overlooked that, The tv is 30 watts and I said 80 in the last post, that was a typo.
The only other thing that has changed is I'll be leaving off the AC and using a mall evap cooler in it's place, it will get the temps inside to 65 or so in the summer there when the air is dry and the moisture is supposed to make it feel 5 degrees cooler than that. 60 degrees should be comfortable enough for us on the weekends we are roughing it. At night it will cool down and we can open the windows to let the inside cool even more for sleeping.

Thanks for trying to help anyways, maybe there are others here that are better able to help with this system.
I appreciate that you tried at least even if you are unable to actually provide any advice or expertise.
God Bless.

Lumisol

BB. said:

A "typical" efficient 120 VAC refrigerator freezer uses around 1,000 to 1,500 WH per day (depending on specific model, size, weather, how clean the coils are, age, how often you open the door, freezing ice cubes, etc.)... Usually around 120 Watts and 50% duty cycle (120w * 0.50 * 24 hours per day = 1,440 WH per day). Note--Starting surge for an induction motor capacitor can be as high as 5x running power (i.e., 600 VA starting surge). Also a frost free fridge/freezer has a ~600 Watt evaporator defrost heater). Nominally, a 1,200 to 1,500 Watt AC inverter minimum is good for running a full size energy start fridge + lighting, RV water pump, laptop, etc..

And there are other options. Get a 7-10 cuft chest freezer and an external thermostat. Still a 120 Watt compressor, but ~250 WH per day (0.25 kWH per day). And still need a ~1,200 to 1,500 Watt AC inverter minimum.

Or, there are DC compressor fridge/freezers--As a fridge, they can run near 250 WH per day too (and no AC inverter)--However, DC refrigerator/freezers are typically quite expensive--Over all, they may not save you much money.

Note that AC inverters do use energy just to turn on. A 300 Watt unit may use 6 Watts. A 5,000 Watt unit may use 20-40 Watts or more (40 watts * 24 hours per day = 960 WH per day--Almost as much as a fridge).

With flooded cell lead acid batteries (the least expensive, and fairly forgiving, but require maintenance), there are two criteria that set the size of the battery bank (AH and voltage).

First is--Usually the optimum price/performance battery bank is 2 days of storage and 50% maximum discharge (or 4x daily load) (1-3 days of storage is the typical min/max range).

The second is sizing the battery bank to support your peak loads. A lead acid battery bank is typically sized for 20 hour discharge rate (5 hours per night, 2 nights, 50% maximum discharge). The maximum continuous current is typically an 8 hour discharge rate (remember that the apparent capacity of a battery drops the faster you discharge it--But these numbers are close enough for us at the moment).

And the fastest you would discharge the battery bank would be a few minutes to an hour so at a 5 hour discharge rate. And for a few seconds of surge, 2.5 hour discharge rate. There are other battery chemistries that have higher surge current, but cost more, and have "other issues" that need to be addressed.

In general, you want to pick as small as loads as you can--It it almost always cheaper to conserve energy than it is to generate the energy.

Roughly, 1,000 WH (1 kWH) per day--Good for a cabin with LED lights, RV water pump, cell charger, laptop computer.

3,300 WH per day--Add refrigerator, well pump, washing machine, LED TV... Basically a near normal electrical life for a very efficient off grid home.

Get up to 10,000 WH per day--300 kWH per month--A relatively efficient on-grid home. And a very large for an off grid power system.

While you pay around $0.10 to $0.30 per kWH (North American) for utility power--It is very easy to spend $1.00 to $2.00+ per kWH for off grid power (one member here has his off grid power down towards $0.50 per kWH--But that takes work).

For lower cost AC inverter, Cotek and Samlex (same mfg., different sales channels?) would be a place to start.

In any case, define your loads first, then design a system to support the loads.

An alternative, if you have limitations (space for batteries, space for panels, how much you want to spend, etc.)--We can figure out a system that will (hopefully) meet the limitations but still support your loads.

Of grid solar is not cheap.

-Bill

From what you have said here, I went through and estimated the power use per day:
A fridge at 80 watts running about 3 hours a day-    240 wh
Lights (small 1 watt LED)-                                           20wh
TV 30 watts for 4 hours-                                           120wh
evap cooler at 80 watts for 5 or 6 hours -                 560wh
misc small battery charger use (phone, etc)               50wh
Total used per day-                                                   990 wh per day (usually less)
Adding some cushion we can assume a daily load of 1200 wh although it will never actually reach that high. 

Will the 6 volt batteries at 225 ah each put in a 48 volt array and producing 10.8 Kwh of storage.(according to photowhit's calculations)
be enough to last a day before being recharged the following day by a PV array (5 at 285 watts, producing about 5 x 285 = 1425 watts x .75 (for normal conditions) = 1068 watts per average hour of sun light.)
When I used an ice chest the ice lasted 2 days and I'll be adding a lot of extra insulation to the fridge when it is installed in the space the old fridge was in.

Could I get by with fewer cells in the battery bank or a smaller PV array?

westbranch

Bill said
A "typical" efficient 120 VAC refrigerator freezer uses around 1,000 to 1,500 WH per day

UNLESS you are going to be there and shut the power off/on many times per day you will not get consumption of 240Whrs per day it will be 1000 to 1500Whrs...
that is the reality of it all....

Photowhit

Lumisol said:
Thanks for trying to help anyways, maybe there are others here that are better able to help with this system.
I appreciate that you tried at least even if you are unable to actually provide any advice or expertise.

There are few with my background and expertise. the fact that I have replied twice and you have changed what you have said/defined is truly infuriating.

Lumisol said:

...to use a 3000 watt A/C(only during the day hours),...

Lumisol said:
The fridge is 80 watts when running and only runs a couple hours a day. How is that 1 kwh? It looks more like 160 to 240 wh to me unless I am missing something. The temps inside the RV will be only around 75 degrees and the fridge is getting a lot of extra insulation in the installation of it. It is only 3.2 CF.

I am one of the few people here that have run an Air conditioner on a minimal system. 

One last suggestion, would be to put your fridge on a Kill-A-Watt meter and see what it actually uses.

I do get the idea you are just playing. I've been through it before, I'll be through it again!

Lumisol said:
I appreciate that you tried at least even if you are unable to actually provide any advice or expertise.
God Bless.

Please understand that this is using the lords name in vain, if you fee this need to use it to taunt, you have problems beyond the reach of this group. Please grow up, grow old, know when someone is trying to help you.

BB.

I am not sure I understand running the fridge at 80 Watts for 3 hours per day... If you convert a chest freezer to a refrigerator--Yes, you can get down towards that level of power usage (but they still take 100-120 Watts to run the AC compressor, and have the higher starting VA ratings).

http://forum.solar-electric.com/discussion/42/chest-freezer-as-a-chest-refrigerator

-Bill

mcgivor

@Lumisol said
 How many batteries (WH) are needed to run a 750 watt microwave for 10 minutes and a tv and fridge for 4 or 5 hours each pulling 80 watts a piece? The lights are all led at 1 watt each and will only have a couple at a time running and only for a couple hours. The system will then have 14 to 30 days to recover.

If these are the loads, the largest is the microwave, in terms of demand, not overall consumption, so the inverter should be large enough to satisfy that with enough headroom to cover the poor power factor, so a 2000 watt inverter should be a good fit.
Personally I would suggest a reputable  name brand, 10 Kw seems excessive, yes they do self consume, the larger they are the more they consume, the reason for choosing a good fit rather than the largest output capacity. Stick with pure sine wave, less potential for problems with electronic/motor  loads,  which basically is all your loads. The inverters  suggested by  @Photowhit are good examples of high quality, middle quality names such as Samlex and Cotek are also good choices, i've no experience with Aims inverters, or Yugo cars for that matter, but their reputation would steer me clear of both, but each to their own.

So the best is to choose an inverter so as to establish it's self consumption, define all loads with run time, no matter how seemingly insignificant, that is step one, this is what my rough calculation looked like.

Refrigerator       80W × 12h=966 Wh
TV                       30W × 5h=150 Wh
Lights                 10W × 3h=30 Wh
Microwave       750W× .25h=187Wh
Inverter             33.6W× 24h=806Wh

Total        2169Wh

This is an example of step one, add or change values as required. 
NOTE The inverter figures were for a Cotek 3000W 48v inverter on 24 hours, in power-cut save mode would be less but difficult to estimate. The Aims 10 Kw figure in the calculation, on 25h would be 3600Wh, more than the total, simply by using a smaller/better unit.

It is impossible to a design a system without this first step.

mcgivor

Added your extra loads, hint, never be conservative with useage.

Refrigerator       80W × 12h=966 Wh

TV                       30W × 5h=150 Wh

Lights                 10W × 3h=30 Wh

Microwave       750W× .25h=187Wh

Inverter             33.6W× 24h=806Wh
Evap.cooler     80W×6h=480
Mis charging  50Wh

Total        2699Wh

Estragon

The fridge load *could* be ~250wh/day. A regular AC fridge will be about 1500wh. Turning it off and on might just trigger a defrost cycle each time and end up using even more power.

OP mentioned it being 3.2cu.ft. If this is just an unmodified bar/dorm fridge it would still be a power suck. If heavily insulated though, consumption might be a lot lower.

I have a home built box with marine/rv DC compressor which uses ~200wh/day when used as a freezer. It takes several days to thaw even after the compressor is turned off.

The only way to know is to measure it in normal operating conditios for a few days.