Calculating solar capacity

[Kroswind]

So, I've been running some numbers, trying to size a solar system currently. 

My primary concern here is being able to power a high end gaming laptop for most of the day.  This things a monster.  From what I've gathered, its got a 330 watt AC adapter, and the battery inside the laptop is 80 watt hours.  The battery life itself is pretty poor, for obvious reasons.  I believe I'll most likely have to run this off an inverter.  It uses a 4-pin DC connector, which is non-standard.  Its not the small DC jack like most laptops are these days.  So I will also have to factor in the power loss of the inverter.  I also have 2 LG monitors that come with 32 watt adapters, that I would also need to run with the laptop.  I do graphics work, and need to be able to run these 3 things for at least 8 hours a day. 

Is this viable with a solar setup?  I am hoping to get 2 300-320 watt solar panels, but am unsure exactly what kind of amp hours I would need in a battery bank.  I do plan on hopefully going out west at some point, but for now I'm stuck in the midwest, so I'm figuring only on 3-5 hours or actual sunlight on an average day.  Based on some old calculations I did, I was thinking somewhere in the realm of 700-800ah battery bank to try and account for losses and cloudy days, but I'm not sure if this is correct.  If I can, I would also consider running one of the smaller dometic fridges and some small things like lights/fans, but these are unnecessary.  Whats necessary is the laptop and monitors.

How exactly do I calculate the usage of the laptop?  Being that I'll most likely need to run this off an inverter, I'm not totally sure what calculation I need.  The monitors I believe I can run off 12v directly, so I don't think I'll need to use an inverter for those. 

I also have the small yamaha 2000 watt generator that I had planned to run higher draw things off of.  So at this point I'm wondering, is solar viable/worth it, or should I just ditch solar all together and run everything off the generator alone?

 

[Optimistic Paranoid]

How exactly do I calculate the usage of the laptop?  Being that I'll most likely need to run this off an inverter, I'm not totally sure what calculation I need.  The monitors I believe I can run off 12v directly, so I don't think I'll need to use an inverter for those. 

Don't calculate it.  Measure it.  Get yourself a Kill-A-Watt meter, plug your stuff into it, and run it for a while.  It will tell you everything you need to know. 

Once you've got some solid numbers to give us, come back and there are people here who can tell you exactly what you need in the way of solar panels and battery capacities.

https://www.amazon.com/P3-P4400-Ele...F8&qid=1491768604&sr=8-1&keywords=kill+a+watt

 

[SternWake]

https://www.amazon.com/Ensupra-Elec...rd_wg=C1PrO&psc=1&refRID=WNKCHYDT75PHJDQQTFJA

The meter above supposedly also measures the start up surge amperage/ wattage on the circuit when compressors or electric motors are used. BradKW ordered one for this feature. Not sure how well it operates.

Looks like you will need a lot of battery and recharging capacity just for your entertainment system, disregarding other electrical consumers, which cannot be disregarded in real life.

 

[Kroswind]

https://www.amazon.com/Ensupra-Elec...rd_wg=C1PrO&psc=1&refRID=WNKCHYDT75PHJDQQTFJA

The meter above supposedly also measures the start up surge amperage/ wattage on the circuit when compressors or electric motors are used.  BradKW ordered one for this feature.  Not sure how well it operates.

Looks like you will need a lot of battery and recharging capacity just for your entertainment system, disregarding other electrical consumers, which cannot be disregarded in real life.

Thanks for the responses.  Can I get one of these meters at a local hardware store? 

Looks like our definition of "entertainment system" is a bit different.  I work full time at a print company(hence why I need it to run 8 hours), and all my work is virtual.  I also produce 3d graphics which is another reason I need powerful hardware.  Multiple screens are crucial to my workflow.  Without them, I cant get things done nearly fast enough.  The fact that I can use it in my downtime is a bonus.  A fridge wont do me any good if I cant afford to feed myself.  See where I'm coming from?  The job is a necessity, everything else is a luxury, and the job revolves around a laptop and monitors.

I'll post back with the numbers once I get the meter.  Thanks.

 

[Optimistic Paranoid]

Looks like our definition of "entertainment system" is a bit different.  I work full time at a print company(hence why I need it to run 8 hours), and all my work is virtual.  I also produce 3d graphics which is another reason I need powerful hardware.  Multiple screens are crucial to my workflow.  Without them, I cant get things done nearly fast enough.  The fact that I can use it in my downtime is a bonus.  A fridge wont do me any good if I cant afford to feed myself.  See where I'm coming from?  The job is a necessity, everything else is a luxury, and the job revolves around a laptop and monitors.

I think the problem is that you DESCRIBED it as a "high end gaming laptop".

In the future, describe it as a "high end laptop/graphics workstation" and there won't be any confusion.

 

[Optimistic Paranoid]

Thanks for the responses.  Can I get one of these meters at a local hardware store? 

Maybe.  I did a quick search on the Kill A Watt on Home Depot and Lowes.  Home Depot showed it, Lowes didn't.  Your local mom and pop?  I dunno.

 

[John61CT]

You did call it a gaming setup.

If you take solar out of the picture, you will murder your batteries by charging them all the way to 100% full way too rarely, unless you get on mains power at least 4-5 nights a week.

Many people do just that, long as you're aware, buy cheap true deep-cycle like Sam's Club or Batteries+ Duracell Golf Car GC2s in 6V pairs, and the whole bank at once, not adding later.

Solar means you can run the genny an hour or two each morning get the bank to 80%, maybe 90% cloudy days, and then let solar get them up to true 100%, ideally every day. Then it may be worthwhile spending more on pricier batteries that will last for many years treated right. Buy as much solar watts as will fit on your roof.

Minimum bank size should ensure hardly ever dropping below 50% SoC, and most people say even when you will go for two days without charging. If you are getting them to 100% full regularly, then getting a bigger bank will make them last much longer, but space and weight may be a limitation.

If you spend a lot of time driving, maybe look at improving on your stock alt, but that may not be worth the extra investment if you already running a cheap gennie.

Flooded will let you monitor SoC with a cheap hydrometer. Otherwise invest in a good Battery Monitor.

Sent from my Nexus 6 using Tapatalk

 

[jonsun]

I'm going to say the laptop uses about 5a and the monitors 4a combined.

One 300w panel will be plenty

Or 100w if you ever run a microwave or heat plate from a small generator

 

[highdesertranger]

boy I am glad you clarified that. from your first post, to me it sounded like you sat in your van all day playing video games. that's why I didn't respond. Home Depot sells the Kil-a-watt, but they all don't carry it. so do an online search first. get us some numbers and we can help you out. highdesertranger

 

[jimindenver]

The killawatt or equivalent is important because the rated numbers are max. I checked one of my laptops and it never came close to it's rated numbers. What did bring it higher was running the DVD mostly.

When it comes to solar, don't try to calculate it, fit as much as you possibly can on the roof. You can do a lot with solar as long as you have a lot of solar to do it with. With 750 watts on my trailer and 435 watts on my truck I run things ranging from 450w to 470 watts and the solar powers them while charging my batteries at the same time. It's not that hard, I've seen 1000w on a van.

With batteries you need to figure out how much the computer and the rest of your rig uses daily and try to give yourself a day or two of buffer for bad weather. You are not talking chicken feed and it is hell to get behind on a big bank so a back up means of charging is a must. Alternators are great if you drive a lot but a generator is more practical than running a huge engine if you don't.

 

[akrvbob]

We'll know more after you use the kill-a-watt, but my guess is that you can run that comfortably with 600 watts of solar.

The size of the battery bank depends on your patterns of use. If you can run the power-hungry systems during the day then you don't need a huge battery bank because you will have normal usage overnight. But, if you need to use the laptop and monitors at night, then that could be a problem.

If you can run the laptop during the day I'd think 4 gold carts might be good and that would give you a ratio if 600 watts to 440 ah, that's ideal I think. If you have to run it at night, then 6 golf carts might be better.

Being in a cloudy place is a big issue, but enough solar can create a surprising amount of power even under clouds. That's one reason to cram every watt you can on the roof--just that much more power during bad weather. It may be possible to get 3x300 watts on the roof for 900 total. You'll have to run them across the van and they will hang over a little, that should be okay. I did that with mine and it's never been an issue although its only 240 watts.

If you don't have a van yet, I would make getting an extended van a priority so you can get all the solar you can on the roof. Plus, you'll want to leave room for a Fantastic Fan if at all possible--during the summer you'll be very sorry if you don't have one!

Normally I'd be more conservative, but since this is your job, it's just part of the cost of doing business and you do what you have to do.

 

[Kroswind]

boy I am glad you clarified that.  from your first post,  to me it sounded like you sat in your van all day playing video games.  that's why I didn't respond.  Home Depot sells the Kil-a-watt,  but they all don't carry it.  so do an online search first.  get us some numbers and we can help you out.  highdesertranger

ahaha, no, sadly that's not the case.  I wish I could sit and play games all day, but unfortunately work takes up the majority of my time.  I do play games from time to time in the small window of downtime I actually get, but its a rare occurrence these days.  When I play games, its usually in a casino.  When you spend all day working in front of a computer, the last thing you want to do in your down time is to continue sitting in front of a computer.  At least for me anyway.

I called it a gaming laptop because it IS a gaming laptop.  I just primarily use it for work.  I didn't think my life story was necessary in my original post, but apparently it was, so sorry for the confusion.  I always try to get the absolute best possible hardware available at the time, especially when it comes to laptops(which imo, usually aren't that great to begin with, especially compared with a real PC), so I can get the best performance when it comes to 3d modeling applications/renders, and just general longevity of the laptop.  The better the hardware, the longer I can go without having to replace it and swap all my stuff over to something else.  Recreational use is just a bonus.  

We'll know more after you use the kill-a-watt, but my guess is that you can run that comfortably with 600 watts of solar.

The size of the battery bank depends on your patterns of use. If you can run the power-hungry systems during the day then you don't need a huge battery bank because you will have normal usage overnight. But, if you need to use the laptop and monitors at night, then that could be a problem.

If you can run the laptop during the day I'd think 4 gold carts might be good and that would give you a ratio if 600 watts to 440 ah, that's ideal I think. If you have to run it at night, then 6 golf carts might be better.

Being in a cloudy place is a big issue, but enough solar can create a surprising amount of power even under clouds. That's one reason to cram every watt you can on the roof--just that much more power during bad weather. It may be possible to get 3x300 watts on the roof for 900 total. You'll have to run them across the van and they will hang over a little, that should be okay. I did that with mine and it's never been an issue although its only 240 watts.

If you don't have a van yet, I would make getting an extended van a priority so you can get all the solar you can on the roof. Plus, you'll want to leave room for a Fantastic Fan if at all possible--during the summer you'll be very sorry if you don't have one!

Normally I'd be more conservative, but since this is your job, it's just part of the cost of doing business and you do what you have to do.

Unfortunately, I work afternoons and into the evenings.  This is one of the primary reasons I'm wondering if solar is even worth it.  I start work at 2pm, which is after peak sunlight hours here, and well into the late evening.  If solar isn't really going to work for me, what I'd plan to do is set up a battery bank and charge it via my generator or from my alternator while I drive.  I would still like to setup a sizable battery bank that would last a while if possible.  

I do already have a van, and am already into a build.  Its a 98 GMC savanna 1500 high top explorer conversion van.  For the solar, if its viable, I plan to get a ladder rack for a high top van, and run metal reinforcements down the length of the van, so the panels will indeed overhang the roof.  I'm fine with that, as long as I'm able to secure everything properly. 

For the record, I picked up a Kill-a-Watt meter today at Harbor Freight.  They were the only local store that carried them.  None of the near by Home Depots had them.  I set the laptop up and let it run for an hour under what I would consider typical use for my situation.  Browser open with multiple tabs, youtube video playing, zbrush/3ds max/photoshop running, and a drawing tablet plugged in.  This was also plugged into a power strip.  I'm not sure if that makes a difference or not.  If so, I can setup another test using power directly from the wall outlet.  Here's the readings from the meter:

Volts: 123
Amps: Between 0.70-0.80
watts: between 85-95
VA: 90.5
Hz: 60
PF: 0.95
KwHr: 0.08


This was only after 1 hour of use.  There are other settings on the laptop, such as extra fans, that will obviously consume more power.  Turning those on, the wattage jumps up to a little over 100.  I don't generally run these fans though, as they aren't necessary.  If I ever do run them, its usually only for a short time.  I have not tested the laptop under "extreme" conditions.  I can setup something and let it run for an hour, or longer, if you need those numbers, but what I did for this first hour is generally what I'd have going most of the time.  I didn't have a mouse plugged in either, though I believe that would mostly be interchangeable with the drawing tablet.  I usually only use one or the other by itself at any given time anyway.  Most of the time, they aren't used together since the drawing tablet acts as a mouse. 

Is this information sufficient?  I can provide more if you need it.  Thanks for the help.

 

[akrvbob]

Solar will do the job just fine. That's only 8 amps per hour and for 8 hours a day that's only 64 amp hours out of your battery bank. Plus, at least part of the time it's on will be during the day so the whole 64 won't come out of the batteries, maybe half will.

With 4 golf carts you have 220 amp hours per day to use so the computer won't be a problem. If it's cloudy a lot that could be a problem but get a generator and charge off the alternator as well and it should be fine. I think the generator will only be for back-up during long periods of bad weather

 

[caretaker]

since you have a 1500, weight is going to be a factor for your drive train.

 

[Kroswind]

Solar will do the job just fine. That's only 8 amps per hour and for 8 hours a day that's only 64 amp hours out of your battery bank. Plus, at least part of the time it's on will be during the day so the whole 64 won't come out of the batteries, maybe half will.

With 4 golf carts you have  220 amp hours per day to use so the computer won't be a problem. If it's cloudy a lot that could be a problem but get a generator and charge off the alternator as well and it should be fine. I think the generator will only be for back-up during long periods of bad weather

Thanks.  Is 220 amps the best I can get, or could I get higher capacity batteries?  Whats the highest amp hour battery I can get that's still realistic for van dwelling?  I have seen 200ah 6v batteries.  Would those work as well, or is there more to high capacity batteries that I don't know about? I am financially well off and would like to know what kinds of options I have available.  I would like to try and generate/store as much power as I possibly can, and I don't mind spending money to do so. 

Since solar is possible, my next question is, naturally, where do I get the panels?  I have searched around, and it seems to me most places will only sell panels by the pallet, which I don't need.  Can you recommend any sites that will sell just the individual panels and still ship them to me?  Once I get the roof rack in, I'll know exactly how much space I have to work with, but I am hoping to get at least 2 panels in the 300watt+ range.

I am also aware of the weight issue and have considered upgrading my suspension and rear gears.  I have the 5.7 V8, so the power is there, but I do want to take care to make sure I don't bottom out the rear end.  Again, thanks for the help everyone.

 

[MikeRuth]

4 GC-2 Batteries are only going to set you back roughly 240 lbs on weight, they will offer you about 220AH to a 50% state of Charge SOC. Mind you that's 2 batteries in series and then the banks of two in parallel. Others will pipe in on AGM type batteries and LiFi etc. There not my bag, I prefer the good old GC-2 Flooded. Consider where you put them? They all need to go in the same place preferably. I too vote for cramming every watt you can on the roof, but 600 minimum would be my choice or more. I'd also suggest in this case a MPPT controller. I happen to be a fan of MorningStar. Unless you run into several cloudy days I have a good feeling you won't be running short on power.

Another thing, look into weather or not you can do away with the power blocks for the monitors. If they are 12-20 Volts DC in then you can run them straight off the batteries to or with Boosters.

 

[jimindenver]

I have two Morningstar MPPT controllers, so I guess I can say I am a fan. I also have Lifeline AGM batteries but they are really, really REALLY, pricy for your first bank. Not as much as LiPo but more than golf cart batteries. There are a number of options for batteries depending on how much you want to spend and how much weigh you want to drag around. My 675 Ah bank weighs in at a quarter ton, that will take a chunk out of your cargo capacity.

All of my panels, 8 total in four systems have come from craigslist. All brand new too and unbelievable prices.

 

[highdesertranger]

4 golf cart batteries will give you 440 amp/hrs, but that will only give you 220 useable amp/hrs because you should not take your batteries below 50%. then they must get recharged to 100% ASAP, everyday works good. all lead acid batteries follow this rule. also lead acid batteries weigh a lot one GC battery weighs appox 64 lbs. x 4 = 256. some here use Lithium batteries lots of power and super light weight, but there are other issues with them and I am no expert. maybe other will chime in. highdesertranger

 

[John61CT]

A larger bank will give you longer runs between recharging without drawing down too far.

But you do need to replace 110+% of what you take out, nearly every cycle to get the extra longevity benefit.

And not only extra up-front cost, but lower MPG, less storage space and extra wear and tear, lower capacity to carry other stuff.

Better to buy a platform designed to carry your intended load, "beefing up" after the fact is a less effective jury rig.

Big deep-cycle banks are HEAVY.

 

[Optimistic Paranoid]

Since solar is possible, my next question is, naturally, where do I get the panels?  I have searched around, and it seems to me most places will only sell panels by the pallet, which I don't need.  Can you recommend any sites that will sell just the individual panels and still ship them to me?  Once I get the roof rack in, I'll know exactly how much space I have to work with, but I am hoping to get at least 2 panels in the 300watt+ range.

I bought my Kyocera panels from Northern Arizona Wind and Sun.  They shipped them to me via UPS.

https://www.solar-electric.com/residential/solar-panels.html?p=3