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-   -   How much power do you use? (http://www.skoolie.net/forums/f49/how-much-power-do-you-use-25583.html)

yaakbus 01-23-2019 01:38 AM

How much power do you use?
 
I am getting ready to buy my solar system and am wondering how much power people use on average per day. I have some pretty high demands as an entrepreneur using two computers that run 24/7, house fridge, sewing machine and lights.

I want to be able to go a 3-5 days with out charging, so i am trying to figure out how big of a battery bank and inverter I need.

Thank you!

JDOnTheGo 01-23-2019 06:51 AM

The answers will be all over the place because everyone and every setup is different. A meter such as this Kill-A-Watt is a very useful tool for measuring your own power consumption. You connect it to each of these devices, run it for a few days, and then you know exactly what it consumes. You can then size your system using empirical data rather than guesses.

yaakbus 01-23-2019 07:36 AM

I need a minimum of 4800 Watts daily, I was just curious what other people use.

PNW_Steve 01-23-2019 11:20 AM

Yaakbus,

Have you calculated the battery bank that you are going to need to support 4.8kwh daily with a 3-5 reserve?

For a mobile application that is huge!

4800watts * 5 days = 24,0000 watts of usable battery bank. For any kind of reasonable battery life you want to avoid discharging beyond 50% DOD. So..... You will need a battery with 48,000 watts of battery capacity.

So.... A 48 volt / 1000 Amp hour battery bank would work. Now size the solar array that you need to support that.... Keep in mind that you want a C/8-C/12 charge rate. You will need roughly 83 amps available to charge with.

To provide 83 amps at 48 volts you will need, in a perfect world, 2000 watts of solar. Realistically closer to 2500watts minimum.


Perhaps you may be well served by looking at ways to reduce your power needs and reconsider your 3-5 day autonomy.

What you have described would be a reasonable system expectation for a fixed installation but being mobile we have to compromise.

o1marc 01-23-2019 11:26 AM

Quote:

Originally Posted by JDOnTheGo (Post 306614)
The answers will be all over the place because everyone and every setup is different. A meter such as this Kill-A-Watt is a very useful tool for measuring your own power consumption. You connect it to each of these devices, run it for a few days, and then you know exactly what it consumes. You can then size your system using empirical data rather than guesses.

Just got a Kill-A-Watt yesterday and plugged my kitchen fridge in it. I just checked and after 24.5 hours it has used 1.09kwh. How does that equate to need on the system.
I'll plug my laptop in and see what it uses. there's something wrong with the Mac, it has an 80% charge on the battery and must be plugged into the charger or it dischages and doesn't recharge, so I have to have it on the cord all the time..

PNW_Steve 01-23-2019 11:26 AM

I guess that I didn't give a direct answer to your question.

I use about 1.8 kwh daily.

I have a residential refrigerator that runs from the battery bank but I start the generator in the morning to run the coffee maker and hair dryer.

yaakbus 01-23-2019 11:32 AM

Yeah I have calculated it all out. The average home uses between 13-30kwh per day and was just curious as to what peoples average use in their bus was. It was more just a question about how much power people used, rather then how to calculate a system. That part is easy.

yaakbus 01-23-2019 11:37 AM

If you have a kwH and you fridge is using more than that, your system is too small. As far as I have been able to learn through this is, most people use less then 3kwH per day so 600ah battery bank is plenty.

You need to have twice the amount of storage then you have discharge for a healthy system. So you at a minimum need a 2000 watt inverter for a computer and fridge (it that is all you use it for) and 400ah of battery so you dont discharge past the 50% recommendation.

Beyond that, I would say your mac has an issue with the Battery if its not charging.

Quote:

Originally Posted by o1marc (Post 306676)
Just got a Kill-A-Watt yesterday and plugged my kitchen fridge in it. I just checked and after 24.5 hours it has used 1.09kwh. How does that equate to need on the system.
I'll plug my laptop in and see what it uses. there's something wrong with the Mac, it has an 80% charge on the battery and must be plugged into the charger or it dischages and doesn't recharge, so I have to have it on the cord all the time..


yaakbus 01-23-2019 11:38 AM

Awesome, that is good info to know. Do you have a 2000 watt inverter? 400ah battery bank?

Quote:

Originally Posted by PNW_Steve (Post 306677)
I guess that I didn't give a direct answer to your question.

I use about 1.8 kwh daily.

I have a residential refrigerator that runs from the battery bank but I start the generator in the morning to run the coffee maker and hair dryer.


o1marc 01-23-2019 11:42 AM

Quote:

Originally Posted by yaakbus (Post 306682)
If you have a kwH and you fridge is using more than that, your system is too small. As far as I have been able to learn through this is, most people use less then 3kwH per day so 600ah battery bank is plenty.

You need to have twice the amount of storage then you have discharge for a healthy system. So you at a minimum need a 2000 watt inverter for a computer and fridge (it that is all you use it for) and 400ah of battery so you dont discharge past the 50% recommendation.

Beyond that, I would say your mac has an issue with the Battery if its not charging.

It's not a battery issue. Battery, charge port, charger and screen are all brand new.My brother, the computer expert, says it's an intermittent problem on the logic board.

My inverter is a 3000/6000 pure sine. I'm trying to make the system with the most power output with the least amount of batteries so I don't end up with $4k worth of batteries. Looks like my home uses 40kwh a day on average.

yaakbus 01-23-2019 11:46 AM

For example my battery bank that I ordered is 1200ah, which gives me 57.6 kwH of storage. So divide that by 2 and it gives you 28.8kwH to discharge before you get to 50%, or about 5.76kwH per day for 5 days without charging.


Here is a simple tool to help convert the numbers. https://everydaycalculation.com/ah-kilowatt-hour.php

Quote:

Originally Posted by PNW_Steve (Post 306675)
Yaakbus,

Have you calculated the battery bank that you are going to need to support 4.8kwh daily with a 3-5 reserve?

For a mobile application that is huge!

4800watts * 5 days = 24,0000 watts of usable battery bank. For any kind of reasonable battery life you want to avoid discharging beyond 50% DOD. So..... You will need a battery with 48,000 watts of battery capacity.

So.... A 48 volt / 1000 Amp hour battery bank would work. Now size the solar array that you need to support that.... Keep in mind that you want a C/8-C/12 charge rate. You will need roughly 83 amps available to charge with.

To provide 83 amps at 48 volts you will need, in a perfect world, 2000 watts of solar. Realistically closer to 2500watts minimum.


Perhaps you may be well served by looking at ways to reduce your power needs and reconsider your 3-5 day autonomy.

What you have described would be a reasonable system expectation for a fixed installation but being mobile we have to compromise.


PNW_Steve 01-23-2019 11:52 AM

Quote:

Originally Posted by o1marc (Post 306676)
Just got a Kill-A-Watt yesterday and plugged my kitchen fridge in it. I just checked and after 24.5 hours it has used 1.09kwh. How does that equate to need on the system.
I'll plug my laptop in and see what it uses. there's something wrong with the Mac, it has an 80% charge on the battery and must be plugged into the charger or it dischages and doesn't recharge, so I have to have it on the cord all the time..

When I checked my appliances I let the kill-a-watt run for an extended period. I found that the power consumed by my refrigerator varied by a significant amount depending on weather and usage.

I had 0.6kwh to 1.2kwh daily depending on conditions. After 28 days I averaged 0.96kwh daily.

Considering system losses I would divide 0.96 by 0.7 to allow for inverter and other system losses. That tells me that I need 1.38kwh to support my refrigerator.


I wish I could find the original quote. I saw a comparison between your solar/battery system that made a lot of sense.

Your electrical loads are your engine and it needs fuel. Your batteries are the fuel tank and you need to size your tank to support your engines fuel needs.

Your solar & shore power charging are the Gas Station that refills your tank.

That is the order of a typical system design.

Identfy the loads to be supported.

Design a battery bank to support those loads.

Design a solar/shore charging system to support your batteries.

PNW_Steve 01-23-2019 11:54 AM

:)

Here is another simple tool :)

P=IxE

o1marc 01-23-2019 11:59 AM

Quote:

Originally Posted by PNW_Steve (Post 306687)
When I checked my appliances I let the kill-a-watt run for an extended period. I found that the power consumed by my refrigerator varied by a significant amount depending on weather and usage.

I had 0.6kwh to 1.2kwh daily depending on conditions. After 28 days I averaged 0.96kwh daily.

Considering system losses I would divide 0.96 by 0.7 to allow for inverter and other system losses. That tells me that I need 1.38kwh to support my refrigerator.


I wish I could find the original quote. I saw a comparison between your solar/battery system that made a lot of sense.

Your electrical loads are your engine and it needs fuel. Your batteries are the fuel tank and you need to size your tank to support your engines fuel needs.

Your solar & shore power charging are the Gas Station that refills your tank.

That is the order of a typical system design.

Identfy the loads to be supported.

Design a battery bank to support those loads.

Design a solar/shore charging system to support your batteries.

Figuring out the needs is difficult without knowing the electrical needs of each item you will be using, hard to do without all the appliances in hand or research what their electrical requirements are before knowing what CC and battery bank will be needed. I have more than enough solar wattage (2450 if needed) and plenty of inverter (3000/6000)

PNW_Steve 01-23-2019 12:04 PM

Quote:

Originally Posted by yaakbus (Post 306685)
For example my battery bank that I ordered is 1200ah, which gives me 57.6 kwH of storage. So divide that by 2 and it gives you 28.8kwH to discharge before you get to 50%, or about 5.76kwH per day for 5 days without charging.


Here is a simple tool to help convert the numbers. https://everydaycalculation.com/ah-kilowatt-hour.php

That will certainly support the loads you described.

24 of these would meet your spec: https://www.batterystuff.com/batteries/pv-solar/agm/111-ah/gpl-l16t-2v.html

They do weigh 120lbs each and cost $700 each.

I guess a 2800 lb battery that costs $17,00 is doable....

yaakbus 01-23-2019 12:09 PM

Dang your house is a power pig haha. Not that I care, i love to stay warm and cool and not worry, but thats like 33% higher then the average.

I am a software developer so I get it. My computers will sometimes give me an error message that the power cable is not correct for charging my computer IF I have to many things running on a curcuit in my office. So if I plug it into a different outlet or unplug other stuff it works fine.

So it seems as though you just dont have enough power to draw from or made the mistake of putting all the plugs on the same breaker. Which means no matter how much power you have, if is going too many places to do anything unless it is the only thing plugged in. For your sake, i hope that is not the case because that is a huge pain in the ass.

My fridge, hot water heater, heater, ac and fans all have their own breakers. Then I have on curcuit dedicated to driver electronics like back up camera and radio. My desk uses two curcuits. my media center has its own curcuit, the front lights are on one. Back lights on another (with the bathroom). Then I have my outlets broken into 4 sections left and right sides split front and back. And then my outdoor plugs.

It is a little more than one needs but very similar to how a home is actually powered, which is in my mind best for my needs.

Quote:

Originally Posted by o1marc (Post 306684)
It's not a battery issue. Battery, charge port, charger and screen are all brand new.My brother, the computer expert, says it's an intermittent problem on the logic board.

My inverter is a 3000/6000 pure sine. I'm trying to make the system with the most power output with the least amount of batteries so I don't end up with $4k worth of batteries. Looks like my home uses 40kwh a day on average.


yaakbus 01-23-2019 12:15 PM

Totally get it. I am applying high and very loose numbers to how much power I need, using more of a 30% loss rather than the 20% some people use which is still really conservative.

But in the end I need 1250aH to get me my 60kwH for 5 day mark. I have a 25.5cuft residential fridge also, so your numbers are helpful in knowing how much it uses in the real world rather then the energy star sticker.



Quote:

Originally Posted by PNW_Steve (Post 306687)
When I checked my appliances I let the kill-a-watt run for an extended period. I found that the power consumed by my refrigerator varied by a significant amount depending on weather and usage.

I had 0.6kwh to 1.2kwh daily depending on conditions. After 28 days I averaged 0.96kwh daily.

Considering system losses I would divide 0.96 by 0.7 to allow for inverter and other system losses. That tells me that I need 1.38kwh to support my refrigerator.


I wish I could find the original quote. I saw a comparison between your solar/battery system that made a lot of sense.

Your electrical loads are your engine and it needs fuel. Your batteries are the fuel tank and you need to size your tank to support your engines fuel needs.

Your solar & shore power charging are the Gas Station that refills your tank.

That is the order of a typical system design.

Identfy the loads to be supported.

Design a battery bank to support those loads.

Design a solar/shore charging system to support your batteries.


o1marc 01-23-2019 12:17 PM

Quote:

Originally Posted by yaakbus (Post 306697)
Dang your house is a power pig haha. Not that I care, i love to stay warm and cool and not worry, but thats like 33% higher then the average.


So it seems as though you just dont have enough power to draw from or made the mistake of putting all the plugs on the same breaker. Which means no matter how much power you have, if is going too many places to do anything unless it is the only thing plugged in. For your sake, i hope that is not the case because that is a huge pain in the ass.

I don't understand that second paragraph. I only plugged the fridge into the K-A-W.

My electric bill at the house has been running about $100 a month. Doesn't seem like over pig at all.

yaakbus 01-23-2019 12:23 PM

Haha that is insane! I am a bit more budget dependent then that haha.


Quote:

Originally Posted by PNW_Steve (Post 306693)
That will certainly support the loads you described.

24 of these would meet your spec: https://www.batterystuff.com/batteri...l-l16t-2v.html

They do weigh 120lbs each and cost $700 each.

I guess a 2800 lb battery that costs $17,00 is doable....


yaakbus 01-23-2019 12:28 PM

$100/mo for the year is totally normal. I was only kidding about the pig part haha.

What is a KAW? My point was that if your fridge needs 1.05ish kwH and you are only giving it 1kwH, there is not left over power, you are actually at a deficit of .05kwH. Meaning your computer will not charge because there isnt enough power for it in addition to the fridge. So at a min, you need 1.5kwH of power available to charge the computer and run the fridge at the same time.



Quote:

Originally Posted by o1marc (Post 306705)
I don't understand that second paragraph. I only plugged the fridge into the K-A-W.

My electric bill at the house has been running about $100 a month. Doesn't seem like over pig at all.



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