How big of a setup do I need

Discussions about solar power and solar energy projects.
Posts: 3
Joined: Tue May 27, 2014 3:07 pm

How big of a setup do I need

Post by Anarchy » Wed May 28, 2014 12:15 am

I am going to be buying a 25FT maybe a 32F camper and going off-grid. I need to know how big of a solar setup I need

The stuff I would be running:

Toshiba 29" TV 49.6 Watts
Fan (High 58 Watts)
PS3 Slim: 250 Watt (Can do away with it its not a need)
PS3 Cooling dock: Guess 5-10 Watts
Laptop: 120 Watts

5,000 BTU AC 495 Watts (Do not own the AC yet but that's what it rates at) (Only on hot days with nothing else running)

And maybe if I can't get a gravity feed system working good I will install a low powered pump not sure how much wattage those are but it can't be too much.

I live in Kentucky so they don't care what you do as long as you do it on land you own or have permission to do it on.

Any estimation of the how many panels id need and how big of a battery bank, etc will be appreciated.

Site Admin
Posts: 1326
Joined: Thu Dec 22, 2011 11:49 am

Re: How big of a setup do I need

Post by techman » Wed Jun 04, 2014 8:58 am

The best way to figure out what you need is to take the most that you will have running at any given time. A rough calculation of your total wattage combined is about 1,000 watts. Now you will probably not be using all that at once but its a good starting point.

I would aim for about 1,000 watts of solar. You can always start small and build up as finances allow.

Now how many hours per day will you be running these devices? Do some math and figure that out. This will give you your total watt hours needed, which will tell you how many batteries you will need.

I would aim for about ten 200 amp hour batteries for best performance. Again, build up as your finances allow.

Hope this helps

Posts: 2
Joined: Sun Jul 06, 2014 11:15 pm

Re: How big of a setup do I need

Post by dbzarea2000 » Mon Jul 07, 2014 12:48 am

What your wanting is Very Very similar to my setup : That AC is the big one : I have 10 : 6 volts @ 232 amp hours each in series and parallel to make 12 volts . 1380 watts of (6) panels and a Midnite CC. You must know that this system cost be ruffly 5,000 US. And I hunted for deals and like troy did ALL the work myself. The biggest thing is have someone or somewhere to turn to if you are unsure. If you do it wrong you can FRY this entire setup in a second!
This is what I run Every Day on my Solar Setup.
Cable Modem
Cable Box
Alarm Clock
Xbox 360
42 Inch
36 Inch
19 inch
Charged 1 Cell phone : AC to DC adapter to USB
3 Laptops
Dorm Room Refrigerator
7 Cubic ft Ice Chest Freezer
2 Window Box fans
18 DC Lighting
Alternate DC Lighting HF Lights in Shed
DC Ceiling Fan
Occasionally other items. Such as :
Box Fans.
I have a educational video I made if you wish to see it with a break down of wiring. My batteries are monitored via PC with the Midnite CC (the most advanced mppt) I could find. So for instance its 1 am where I am. I can click a button and see my batteries are at 91% at 7 pm this evening the sun set, I will be at 86/87 when the sun rises and this charger has them batteries back at float around 2/3 pm. Sometimes soon depending on the sun. Below is a purely educational vid : 22 minutes long explaining things." onclick=";return false;

Posts: 2
Joined: Sun Jul 06, 2014 11:15 pm

Re: How big of a setup do I need

Post by dbzarea2000 » Mon Jul 07, 2014 6:24 pm

OK : Here we go :
TV 50 Watts ; Fan 58 Watts ; PS3 250 Watt ; Cooling dock 10 Watts ; Laptop: 120 Watts ; AC 495 Watts = 983 Per Hour is what your seeking. Lets just say 1,000 Watts is what you need per hour at a minimum.
So lets take a look at batteries and convert the batteries to WATTS! how do you do this?

So I will use my system to explain : I have a bank that consist of 10 / 6 volts. The bank is wired to a 12 volt so every two batteries is wired in series to make 5 / 12 volt batteries @232 amp hours per 12 volt battery. I have 5 batteries x 232 amp hours ; I have 1160 amp hours. Now lets convert this to watt hours. 12 volts x 1160 amp hours = 13920 Watt hours ; You think that is a lot of watts? ; I can only use 30% so my bank so my batteries live longer. Granted I can use more power, but it shortens the life, a no no if possible because I dont want to buy more batteries ANY time soon. So 30 % of 13920 = 4176 watts in storage in this bank. Now for me I have 1380 watts of panels : So if the sun it out and shinning I can power everything and charge back up to 100%. You really at a minimum want to have at least 12 Hours of power. The problem comes as your ac continues to take that amount of power ALL night. My fridge turns on for 5 / 10 minutes to cool then back off and back to 50 watts / same with the Freezer. So using this Formula you can calculate how many batteries you need. That AC is taking ALOT of power, perhaps find a more efficient one. When the AC is on FAN it does not use nearly that. There is a small window unit that is 5 btu if you can find one, a few folks I know on solar have them. To keep it running all night though you would need a bank twice the size of mine because of the high draw unless you draw the batteries down below 70% / But that shortens the life.
All night draw ; lets say 8 hours on the best senario : 500 x 8 is 4000 watts. You get the idea now I think, Drop the AC then a system half my size can do that. Keep the AC then double it. Unless you use a timmer or if you use it when you need it and monitor it when running it. This is the price to do this type of system and why troy has to watch his system. You cant just let it run ; Unless you go massive. Even I watch my system from my PC as my Charge Controller is also connected to WiFi so I can monitor it.

So know you know if you double the size of my bank you can do it ; but then you also have to double the Panels to take in the charge (I have 6 @ 230 watts each) In addition most 12 volt Charge controllers have AMP limits : Mine is 96 amps the highest intake on the market. You also would need 2 charge controllers one CC for each set of panels, basically if you keep that AC you need to DOUBLE my system. However! Let say you copy my system : you can run the AC only during Peak Sun hours (watch the AMP intake and know when you can run it based on the AMP intake from the panels.

Hope this helps : You can do it, just how much you want to spend. I spend 5,000 to do what I did. However I did top notch stuff ; I did not want any think that would break in 3 months. If you watch my vid, you can see the system for yourself battery bank and all.

Posts: 7
Joined: Mon Feb 09, 2015 2:50 am

Re: How big of a setup do I need

Post by john3voltas » Mon Feb 09, 2015 3:05 am

Hi there.
I know this is a sort of an old topic but I thought I might go ahead and recycle it if everybody is ok with that.
My current power account averages 65€/month which means I am paying a total of 780€/year.
Also from what's been discussed here I know that this setup is worth 5000$ but without the AC it could have been had for about half (~2500$). But since I don't know good deals I'm adding another 500$/1000$.
I wouldn't need the AC so 3000$ to 3500$ would be a rough estimate in my case. I'm great with numbers, ain't I? :P
Now, I'm not entirely sure but I'd say batteries don't last more than 10 years, right? And 10 years may even be an optimistic figure...
So 3000/3500$ break down in 10 years give 300$/350$ per year? Divided by 12 (months) it would go as low as 25$/29$?
Those are very interesting figures.
Did I go wrong at them somewhere?
How long will a setup like this run for (as long as I keep the batteries above 70% at all times)?
After that do I need to buy everything again or can I reuse? What could be reused?
On that 2500$ setup, how much would the batteries cost?
Does this setup need any hard maintenance or would I only need to keep an eye on it every day?
Sorry for so many questions :oops: .

Site Admin
Posts: 1326
Joined: Thu Dec 22, 2011 11:49 am

Re: How big of a setup do I need

Post by techman » Mon Feb 09, 2015 1:29 pm

There are some numbers missing in your work in order to figure your needs properly.

How many Kilowatt Hours are you using in a day or month? That should be on your power bill.

Now, if its monthly then divide that by 30 to get a daily number.

Now multiply that by 3 to get the number of solar panels you need to provide that much power. This is a rough estimate.

Now, dont panic. I am sure these are very large numbers.

Next step is to reduce your power consumption.

Put the TV, DVD Player, Stereo and anything else on a surge power strip with an on off strip. Only plug in what you are using at the current time and keep the power to the surge strip off when not in use.

Switch all your lights to CCFL or even better LEDs to save. Lights account for about 30% of your energy bill.

Get used to sitting in a slightly dimmer room. Get used to less light when not needed. Turn off all lights when not needed. On and off only as needed.

Get rid of the microwave and switch from electric to gas stove to save a lot more power.

Hang your laundry to dry rather than use a clothes dryer.

Get rid of the old tube TV and get an LED TV. One tenth of the energy used.

Turn off the outdoor light (if you have one) or switch to LED floodlights.

Hope this helps some. Please feel free to post your numbers if you want.

Site Admin
Posts: 1326
Joined: Thu Dec 22, 2011 11:49 am

Re: How big of a setup do I need

Post by techman » Mon Feb 09, 2015 1:32 pm

Oh, I forget the other questions.

Some batteries last 10 years. Count on 5 and be happy with more.

Solar panels put out up to 80% of their power up to 20-25 years. They still work but with reduced output. Plan to add more later to boost the failing solar in 20 years. Say 20% more solar power to offset your losses. Then just add more as needed.

Electronics can fail but some last your life time. Hard to predict but you should always count on failures and put aside emergency funds for that.

Posts: 7
Joined: Mon Feb 09, 2015 2:50 am

Re: How big of a setup do I need

Post by john3voltas » Tue Feb 10, 2015 12:24 am

My last bill (December) was 248KWh. Since December has 31 days, that gives around 8KWh/day which multiplied by 3 gives 24KWh on panels only.
Now, how about batteries?
How much (rough estimate) would such a setup cost?
BTW, most my lighting is already LED and the 2 TV's too.
Oh, and how about starting small and growing big? I mean, start with a small setup that only takes care of the wash machines and the fridge and then addon more panels/batteries in a couple of years?
Thanks in advance :)

Site Admin
Posts: 1326
Joined: Thu Dec 22, 2011 11:49 am

Re: How big of a setup do I need

Post by techman » Wed Feb 11, 2015 5:46 pm

Well, the easy part is your batteries. A forklift battery like mine provides about 8 KW of storage. But again you need to figure on low sun days so three of these. If you go with a 24 volt battery bank then most likely you will have double the capacity already.

But I would have extra to be safe.

The 24 KW setup is a bit extreme and you may be able to reduce it but I would say better safe than sorry.

And yes you can start up with a small solar panel array and just keep expanding as finances allow.

Start out with some cheap solar panels online. If you buy about 10 of them on a pallet you can get them for about 60 cents per watt plus shipping. That is cheap.

Then get a forklift battery. Not so cheap but should last 20 years or so.

To start out cheaper just get some golf cart batteries to learn with and expand from there as finances allow.

Dont forget a solar charge controller and a power inverter to power your AC devices.

Posts: 7
Joined: Mon Feb 09, 2015 2:50 am

Re: How big of a setup do I need

Post by john3voltas » Tue Feb 17, 2015 6:45 am

Wow, I just noticed that techman == Troy. Which means that I am talking to THE man himself :ugeek:
Thanks for sharing your knowledge. :)
So, here's my challenge.
A 145w LED TV which is usually powered on for ~7 hours during weekdays and 12/14 hours on weekend days.
The TV will be mainly sucking power only from the battery because it's used at night.
145w x 14h = 2030wh
This means that for 14 hours/day I will have to be ready to spend more than $800 only on batteries to get around 6000Wh, which will allow me to spend circa 70% of my batteries. Besides, a small solar panel won't be able to keep the batteries charged day in day out, right?
Correct me if I'm wrong but a 200w panel in optimum sunlight conditions will recharge 200w per hour right?
Which means it would take more than 10 hours straight of perfect sunlight conditions to recharge 2030w, right?
If the above is true, could I somehow use both the solar power AND the grid power to power up my TV?
The idea would be to save as much as I can with the solar panel but still be able to run the TV on winter days?... :(
Something that would keep an eye on the battery consumption and that would bypass the battery as soon as it gets to only 70%. From then on it would get power from the grid.
I guess going off grid is a bit farfetched in my case (top floor of a condo). I guess all I can do is use some solar power to save on the grid bill, right?

Post Reply