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SkyMan

Newb Solar Questions

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SkyMan

Ok, so I'm trying to get a handle on this solar deal and want to figure out what parts do and are required so I came up with a couple scenarios to educate myself.

 

Scenario 1:  I buy a panel, say 100W, and a 12V LED light, say 5-8W, and connect them.  Will this burn up the light?  What would I need to do this correctly?

 

Scenario 2:  Same as scenario 1 except instead of light I connect a 12V deep cycle battery.  I'm guessing the battery will eventually explode from overcharging.  Is there some battery charge regulator to use?

 

I'll probably have more questions when these are answered.  Thanks.

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Ronin

 

 

Scenario 1: I buy a panel, say 100W, and a 12V LED light, say 5-8W, and connect them. Will this burn up the light? What would I need to do this correctly?

 

I'm no expert but that's never stopped me before...

 

If you could hook the light directly to the solar panel, it might work, during the day :D

 

You need some type of rechargeable light, here's two that I bought on amazon that seem to work really well (note the light stick needs a usb power bank - available at almost any mall or online)

 

http://www.amazon.com/Goal-Zero-14101-Stick-Light/dp/B0045XRK06/ref=sr_1_5?ie=UTF8&qid=1386900945&sr=8-5&keywords=goal+zero

 

http://www.amazon.com/gp/product/B004DMVR94/ref=oh_details_o09_s00_i02?ie=UTF8&psc=1

 

I'm using portable solar panels to charge USB battery banks and then using the banks to charge phones, tablets, lights and run small USB fans at night to make sleeping tolerable.

 

 

 

Scenario 2: Same as scenario 1 except instead of light I connect a 12V deep cycle battery. I'm guessing the battery will eventually explode from overcharging. Is there some battery charge regulator to use?

 

You'll need a solar charge controller that connects between your battery and panel to regulate the charging.

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Woolf

you need a charge controller like this one

 

http://www.cdrking.com/index.php?mod=products&type=view&sid=18416&main=167

 

 

The voltage output of a solar pannel is higher  than the 12 v of the battery and also higher than the about 14 volts normally used to charge a battery

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Paul

You will need:

 

Solar Panel > Solar Charge Controller > Deep Cycle (or Golf Cart) Battery > Load

 

OR, if the loads are 230vac:

 

Solar Panel > Solar Charge Controller > Deep Cycle (or Golf Cart) Battery > Inverter > Load

 

-----------------

 

The controller is the "brains" of the system. It determines how many amperes goes into the battery. If it has HVD / LVD options, it will automatically disconnect or reconnect the battery from the load, at preset voltages, to keep the battery from being discharged beyond a safe point. Read about Depth of Discharge or DOD. 

 

Then, you get into different types of controllers - PWM or MPPT. MPPT being newer technology is superior. But, you PAY for that superiority too. They are considerably more costly than their PWM counterparts. For your application, just wanting to run some lighting, PWM is fine.

 

PWM = Pulse Width Modulation

MPPT = Maximum Power Point Tracking

 

Read and compare, here: 

Trad-PWM-vs-TrakStar-MPPT-April-2013.pdf

 

I currently use a PWM controller:

 

 solar_controller.jpg

 

------------------

The proper way to set up a system for your home is to build it from the load to the array. That is, determine what you want to run, and for how long, and then go from there, backward.

 

Determine Total Load > Determine Battery Size > Determine Array Size

Edited by Paul
Added PDF
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Paul

Here are a couple of formulas that will help you get started: 

watt rating x hours powered = watt hours per day
watt hours per day / system voltage = amp hours per day
For example, you want to power 20 watts of lighting, for 8 hours per night, total.
 
20 x 8 = 160 watt hours
 
Your system, because it is smaller, will be 12vdc. 
 
160 / 12 = 13 AH.
 
Because you would not want to discharge your deep cycle battery beyond 50%, you would must have, at a minimum, a 26 AH battery. In this case and for expansion of your lighting later, you could go with a 50AH battery. 
 
The charge rate should be no less than 10% of the AH rating of the battery - 50AH, 5 amperes, 100AH, 10 amperes, and so on. 
 
So, you would need a charge controller rated for NO less than 5 amperes, preferably 6. (The MorningStar SunLight 10L-12V is a perfect lighting controller. It is a 10amp rated controller.)
 
Now, to provide the charge for the controller to - well, control the charge.
 
The controller is rated at 5 amps x 14.5vdc (maximum charging voltage of a 12vdc panel), would give you a total of 72.5 watts. 
 
Rounding up, a 100 watts panel, for this scenario, would be what you would need to go with. (You could go with an 80 watts panel. But, there again, you would have a bit larger panel for later expansion.)
 
NOTE: Keep in mind that, when you charge batteries up, you need to put an additional 30% of charge back into them than what was drawn from them. If you use 10 amp hours from a battery, 10 amp hours of charging will NOT bring them to a full charge.
 
For the record, my 100 watts Just Solar panels cost me $135 USD, each. Below are the specs for those panels:
 
IMG_0204r.jpg
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Wolfpack

when you figure this whole gig out, can you disclose what it cost you...

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Paul

when you figure this whole gig out, can you disclose what it cost you...

 

Who are you addressing?

 

Mine has already been listed, here.

 

And here.

Edited by Paul

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Scottiev

this isnt a bad source for information http://www.solar-wind.co.uk/     I had a7 Kw onan diesel generator>-charge controller-> 6, 2v 1250ah gel batteries->inverter->appliannces..ran a DC lead also at 12v for my stereo ( car application) , 12v lights ... my freezer and fridge were propane as was my  stove , but i was looking at 12 dc replacements.. the last year i was there i also had a 100w solar panel running to the charge controller but i could have done some finer tuning on that..cost?? it wasnt cheap , but i went top of the line on everything , about $8000 US or maybe a bit more , but in 3 years i only had one battery fail ( replaced under warrenty) and the system ran in 85 degree heat in the summer and -50 below in the winter..about $2000/yr i guess isnt too bad for electric if your 40 miles up river , boat access in the summer and snowmachine in the winter....

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SkyMan

So Paul, how many batteries and panels do you have in there?  You've probably posted this elsewhere but not in the mood for digging right now.  :)

Edited by SkyMan

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Paul

So Paul, how many batteries and panels do you have in there?  You've probably posted this elsewhere but not in the mood for digging right now.  :)

 

I am currently running "under powered" on my panels. But, I knew this when I began the project. I couldn't put everything into one project, leaving myself shy on others.

 

I have four batteries, all wired as the image depicts below, at 120 AH each. I have three (3) 100 watts Just Solar panels on the roof of the farm house. I should have at least three (3) more panels for these batteries. But, I am going to split them up as soon as my other controllers come in. Rather than one large array, I will have several smaller ones, each performing specific duties.

 

batt_v_new.gif

 

The wiring diagram is explained in the "How to correctly interconnect multiple batteries to form one larger bank" thread, more specifically, in the second post. Proper wiring of your batteries is very important. Proper watering and maintenance of your batteries, is very important. Proper charging of your batteries is extremely important.

 

I gambled that, with all the sun hours we get here, the panels would not have any issues keeping the batteries charged. I was right. They have been doing quite well, in fact. It would take a number of days of rain before the batteries would be to the point of low voltage disconnect. So, I have at least five days of autonomy. But, before rainy season arrives again, I will have the bank split up and connected to two separate arrays, which will put them matched exactly as they should be.

 

Had I been in northern North America, I would have never considered doing that. However, living as close as we do to the equator, they would be fine until rainy season sets in. I have several months to get my stuff in order.

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Paul

Keep in mind, one thing here, TJ. 

 

Recall when I mentioned about the comparison of a PWM and a MPPT controller. The PWM controller, while okay technology, is not as good as one that offers MPPT technology. MPPT controllers are more efficient, and secure more power from the array, turning it into charging amperes. This same power, if wired through a PWM controller, would simply be lost. So, how much better would my array be charging right now, had I been able to go to the expense of an MPPT controller? (At the time we purchased our parts, I could not find an MPPT controller in country. (It's due to the cost differences, for sure.) Of course,, I will be able to let you know in a couple of months. That is when my Midnite Kid should arrive here. It will be put online the day it comes in.  

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SkyMan

I have four batteries, all wired as the image depicts below, at 120 AH each. I have three (3) 100 watts Just Solar panels on the roof of the farm house.

Very good, so what did you determine as your typical load to come up with this?

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SkyMan

Keep in mind, one thing here, TJ. 

 

Recall when I mentioned about the comparison of a PWM and a MPPT controller. The PWM controller, while okay technology, is not as good as one that offers MPPT technology. MPPT controllers are more efficient, and secure more power from the array, turning it into charging amperes. This same power, if wired through a PWM controller, would simply be lost. So, how much better would my array be charging right now, had I been able to go to the expense of an MPPT controller? (At the time we purchased our parts, I could not find an MPPT controller in country. (It's due to the cost differences, for sure.) Of course,, I will be able to let you know here, in a couple of months. That is when my Midnite Kid should arrive here. It will be put online the day it comes in.

Yes, I looked through the link and it seemed like there was little benefit with the MPPT for low use which I would assume I fall under at least for the next few years. And what's a Midnite Kid?

 

Also, the pic of your controller has battery sensor leads. How are those connected?

Edited by SkyMan

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Paul

Yes, I looked through the link and it seemed like there was little benefit with the MPPT for low use which I would assume I fall under at least for the next few years. And what's a Midnite Kid?

 

Take a look at the Midnite Kid Release thread. I am on a list of people who will get the very first of these units when they are released, even before distributors are entitled to do so. They are called "Beta Kids". The firmware will be new, and tested by myself and others who secure these units. They will also come with a life time guarantee, something no other controller on the market currently has. (When they are in their full release stage, they will only have a two year warranty, if I recall correctly.) It's nice knowing I will never have to buy another "Kid" from Midnite. Not to mention, the firmware can be updated via your computer. 

 

MPPT controllers do not have to run the same voltage off the array, as the battery bank. That is, I can run up to 150vdc from the array, and run 12, 24, or 48 volts dc, off the batteries. A PWM controller cannot perform this way. If the batteries are 12vdc, so must be the array. And, as previously stated, an MPPT controller will turn additional voltage into amperes, so that extra energy can be used to charge the bank as well.

 

I have one PDF attached to the Kid release thread. But, here is another brochure I have, as well: 

spec_sheet_kid_front_back.pdf

 

 

Also, the pic of your controller has battery sensor leads. How are those connected?

 

Sensor wires, which can be quite small - very, very little electricity flows through the conductors. They are used to sense the "actual" voltage at the batteries. You attach one end to the controller, and the other to one battery in the battery bank. Typically, this is for a bank of batteries that are say, five meters (or more) from the controller (My batteries are only 1.5 meters from the controller). But, I figure the more accurate the actual reading directly off the batteries, the better the controller can charge them.  It's there, so why not use the option? Not to mention, it took all of one minute to connect it.

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Paul

Very good, so what did you determine as your typical load to come up with this?

 

Actually, I didn't. However, I did already have an idea as to what we would be running at the farm. More importantly, I already had the batteries from a purchase I made, when an English developer was leaving Sihanoukville. He gave the batteries to a buddy of his. His buddy sold me three of the four batteries, almost brand new, a voltage inverter (800va), and a 24" Philips monitor, all for $250 USD. He regretted it later. 

 

Since I had the batteries, I figured I would work from the bank, determine what loads I wanted to run off them, and then determine how many watts I would need coming off the array.  Worked out great. 

 

On my hottest night at the farm, I ran the inverter and my fan (on high) all night, as well as one 12vdc light, and other 12v lighting in and around the house, from sun down til bed time. The battery bank level indicator never dropped off solid green - never has, in fact. 

 

My new Purse Sine Wave inverter only draws .4 amp while idle, plus whatever load I will put on it. The old Modified Sine Wave inverter was drawing 1.4 amperes while idling. Not to mention, we are changing all the CFLs out for LEDs next.

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