Small Solar System

20 Posts
Sep 4, 2008 09:18 pm
Small Solar System

Hello,

I bought ten 15 watt panels from Canadian Tire (The Eliminator ones...12v and 1amp).  I also bought two deep cycle 100ah batteries, a 30 amp charge controller and a 3000 watt modified sine wave inverter.

Thought it would be straightforward to setup, but now that I have all the pieces, I'm not so sure.

On the box, it says "you can connect up to 10 panels together".  - But the panels have nothing coming out of them except 1 cable with a little box with holes at the end.  (assuming 1 negative hole and 1 positive hole).  - But how do I connect them together so that I get a 12v, 10amp system?



Thanks,
Patrick
 
462 Posts
Sep 5, 2008 01:52 pm
Re: Small Solar System

Patrick, twist all the positive wires together and then all the negative wires together. Then tie each of those two groups to a suitable gage wire that can handle the ten amps total. (Usually you use an electical combiner box that has screw contacts, a bunch for the smaller individual wires and one for the total output wire that will lead to your PV controller.)
 
184 Posts
Sep 5, 2008 05:24 pm
Re: Small Solar System

And make sure you have HEAVY wire (maybe 4 or 6 guage) from the batteries to the inverter.  Keep it as short as you can.  With a significant load on the inverter, you're going to have high current there.  For example:  A 500-watt AC load will result in about 50-amps of DC current flow, assuming you have a 12-volt DC to 120-volt AC inverter. 
 
20 Posts
Sep 7, 2008 09:04 am
Re: Small Solar System

Okay thanks ... Do you know where I can get one of those "combiner boxes" ?..checked home depot and rona...both said they had no clue what I was talking about ... Think it would be pretty messy to have 10 wires all twirled up together and then twirled onto a thick gauge wire...

And - To your point, 50 amps for a 500w draw.....

So this is a 3000w inverter that I have, and it says in the manual that it cannot handle anything higher than 12v DC from the batteries...

So if I am using it to let's say power a 2500w oven, then does that mean it would be drawing 208 amps from the battery? (2500w / 12v)...that's alot of amps!

Thanks, appreciate the help.
Patrick
 
3 Posts
Sep 7, 2008 12:18 pm
Re: Small Solar System

Hello Patrick, I am located in Mississauga Ontario, so I  follow the CSA code. I have posted information as such in the members gallery area. Check it out and see if the information is usefull to you. It is not much different to the US NEC.
 
20 Posts
Sep 7, 2008 12:48 pm
Re: Small Solar System

Hi Romeo,

Thanks.  I went to see the diagrams in the gallery you posted, and I understand the principles behind them.  I am not an electrician, so codes etc I have no knowledge of.

What I am concerned about is the potentially high loads I will be transferring from the batteries to the inverter.  I bought a 3000w inverter because I am planning on using that much.  And the inverter is a 12v DC to 110AC inverter.  So does that mean if I'm drawing 3000w, the batteries will be supplying 250amps at 12v to the inverter?  If so, how dangerous is this amount of current?  And how thick of a wire do I need?  Any special connector clips needed?  (heavier gauge etc)

Also, my panels are supposed to be 15watt panels.  (12v - 1 amp).  But today, I decided to test one with a meter.  When I hook it up, it shows 24.4v ??  Does this mean my panel is defective, putting out the wrong voltage?  Just paranoid because I have no idea what will happen if I hook up the wrong voltage to my 12v 100ah deep cycle batteries.  Could blow them up for all I know.

Thanks for your help
 
462 Posts
Sep 7, 2008 12:58 pm
Re: Small Solar System

Patrick, those stores should have them. They may call them a junction box. Or just look for what I described, several smaller contacts connected to one large contact. Actually what you are dealing with isn't that big a deal. The ten small wires can be connected to a larger wire using copper wire clamps.
 As far as current draw. At best, you are making 10 amps per hour. That's only 50+ amps a day. You can't expect to draw 500 W or 2500 W at 12 volts (40 - 200 amps) for any length of time before you drain your 100 amphour battery.
 
20 Posts
Sep 7, 2008 01:06 pm
Re: Small Solar System

Thanks Tom.  Yes I understand that I'm not generating a whole lot of power with these.  But once all setup successfully, I intend to add more panels as time/money allow.  My end goal is to be completely off grid.  Based on my usage (looked at last 24 months), I'm using about 700khw per month and that includes my geothermal heat pump furnace.  So a 5kw panel array should meet my needs for complete off grid.

Just starting small with this ~0.15kw system Smiley  Only need to make it 35 times bigger !! lol

Thanks again... I'll go back and ask for a junction box.

Patrick




 
20 Posts
Sep 7, 2008 10:31 pm
Re: Small Solar System

Okay, got a junction box (was essentially just a metal box with holes in it) and got some of those twist things to twist and connect wires together.  So think I have that solved.

Couple more questions - If I am ever using 3000w of electricity from the batteries to the inverter, at 12v, that's 250 amps! (I think?).... What gauge of wire do I need to support this?

The biggest wire I could find was a car battery wire (think it is 4 gauge?). - Would this suffice?

For the connections from the solar panels to the charge controller, I bought 20amp "heater" wire... is that ok?  Same for the connection from the charge controller to the batteries.. I intend to use the 20amp "heater" wire (it's a red wire).

And last - To connect my two 12v deep cycle batteries in parallel, is the "battery cable" big enough?  And is there any risk that I electrocute myself when connecting them?  Any special order I need to follow? (example; connecting negative to negative first or the other way around?).

I know it is only 12v, but it's 100ah...isn't it the amps that are dangerous?

Thanks,
Patrick


« Last Edit: Sep 8, 2008 12:40 am by Patrick Guenette »
 
20 Posts
Sep 8, 2008 12:40 am
Re: Small Solar System

Sorry last question - I have a Franklin 3/4hp well pump, setup with a control box in my basement.  The box says 230v.  Anyone have any idea how many amps this pump needs?

Thinking I will need a 120v to 240v transformer hooked up to my 120v inverter to use it.  But the inverter is only 3000w.  So if I use a transformer to boost the 120v to 240v, that means it will only be able to pump out 12.5 amps @ 240v right?

Think the pump is on a 15amp breaker.  - But hoping it would not use more than 12.5 amps @ 240v...anybody know?

Thanks,
Patrick
 
351 Posts
Sep 8, 2008 02:15 am
Re: Small Solar System

230V ac is two phases of 115V that are 180 degrees out of phase to each other. A transformer will not solve the problem.
You could do it with two piggy backed inverters.
But you might find it cheaper to change the motor/pump.
 
462 Posts
Sep 8, 2008 10:13 am
Re: Small Solar System

Patrick, take a look at the "Learn" section here. It has a wire chart that will help you determine the gage wire you need and how far you can run it base on the amount of amps you are drawing or you can find one easily online.
 You mention you will grow your system. You may also consider using smaller dedicated systems, somewhat like what you have now, to operate specific loads. That way there if you purchase panels in the future, and they are not compatable, you can hook the two systems up separately and reliablity goes up.
 As far as the 230 pump goes, it is 3/4 HP, so 750 Watt/HP x .75 HP = 570 Watt  and 570 Watt/ 230 V =2.5 amp. Or 570/12 V = 47 amp. Look for a metal tag on the pump itself. It should have the specs there. There may be a surge or startup current that is a little higher than this. This would translate into approximately 1/2 hr to 45 min max that you can operate this pump without degrading the battery.
 Then it would take your current setup of 10 amps at 12 volts approximately 8-10 hrs to recharge the loss on the battery.
 Hooking up your batteries in parallel is the same deal as the panels, all the negatives and all the positives connected. There may be some battery diagrams here in the learn section. Start with the ground connection then neg then pos. This way here there is alway a connection to ground while wiring and hopefully and current will go that way first.
« Last Edit: Sep 8, 2008 10:44 am by Tom Mayrand »
 
20 Posts
Sep 8, 2008 11:38 am
Re: Small Solar System

Uhoh..now you just scared me! Smiley  You have to ground the batteries??

The only ground anywhere in the whole system is on the inverter.  The solar panels are plastic everywhere except for the glass and the 2 wires coming out (1pos and 1 neg).  - No ground wire and no metal pieces to attach a ground wire to.

Plastic charge controller also has no ground.  - Only has 4 receptacles.  (1pos and 1neg for solar array and 1pos and 1neg for battery connection).

When I read the instructions in the book that came with solar panels, it never mentions any grounding...

Batteries have 2 connectors each (1pos and 1neg)... So where/how do I ground them??  If I connect neg to neg and then pos to pos, will I get electrocuted?  (sorry if this sounds stupid)


Thanks,
Patrick
 
462 Posts
Sep 8, 2008 11:56 am
Re: Small Solar System

Patrick, in the grand scheme of things, your system is small so major damage from a lot of power is not to big a deal. If the inverter has a ground then just use that. All other component are connected so they too are somewhat grounded. The gound is an emergency negative so you would probably hook up any grounding lines to the neg. If you cannot find information here, Home Power Magazine has a lot of schematics you can look at.
  You can also/should install circuit breakers or fuses in line anywhere you think a surge may occur to protect any equipment. Shut offs or disconnects are something to consider also, especially in larger systems.   
 
3 Posts
Sep 8, 2008 11:12 pm
Re: Small Solar System

Hello Patrick, you need to install your equipment according to code rules. This would provide the safety necessary for your installation. Your concern about the high current drawn on the batteries is valid. You have to do a little math in balancing your system so it works propperly.

Where will the system be installed? Fixed residential? Portable remote locations?

Does your inverter have a floating NEUTRAL? 

Your inverter (3000 watts) cannot be loaded to its maximum rating for a prolong time. I would suggest you limit your maximum load to 80 percent capacity (2400 watts).

Your calculation regarding currend drawn is correct and is not a problem once you install the devices in the propper enclosure and use the propper size of conductors required to handle the amperage drawn. Visit your local electrical supply store for the propper equipment required. Correct fuse sizes for circuit protection is required. Locate the inverter as close as possible to the battery bank. Extreme care should be exercised in connecting batteries to the inverter. A shorted battery can deliver very high currents (1000 amps).

The 24.4 volts DC you measured is the open circuit voltage of the panel (no load connected)check panel specifications.

I realize you are embarking on a project with limited knowledge. I would suggest you do some reading on the subject to expand your knowledge base. Take your time and do it right. Be cautious in your approach, electricity KILLS! Install acccording to electrical code rules.

Regards, Romeo






 
20 Posts
Sep 9, 2008 11:15 am
Re: Small Solar System

So I went ahead and did the installation (very carefully!).

Have the 2 batteries connected in parallel, connected to the inverter and connected to the charge controller.  Charge controller is connected to 8 of the panels via junction box.

I'm using 6 gauge "solid" wire to and from the solar panels to the charge controller, and the same wire to the batteries. 


Using 4 gauge "battery cable" to connect the batteries in parallel and to the inverter.  The 4 gauge wires are 12 inches long from battery to batter and 24 inches long from battery to inverter.

No fuse or breaker on the positive cable from the battery to the inverter yet.  - Any suggestions as to where I could get one?  Went to various hardware stores (home depot etc) and none of them had a 250 amp fuse/breaker for 4 gauge wire.

The 6 gauge wire (it's actually "Heater" wire apparently, and it's rated for 20amps at 110v) is about 25 feet long and the wires coming out of the solar panels are 12 feet long.  So that makes the total length from the panel to the inverter about 37 feet.  - With this gauge wire, am I losing very much efficiency?

It's raining here today (no sun), but I put 4 of the 8 panels outside, just flat, not pointing in any particular direction (did this at 9am), and the charge controller is displaying 00.3 amps.  So each of the panels is generating 0.075amps lol.  Hope that is due to the rain and not the cable lenght.  They are rated at 15watts - 1amp @ 12v.

Charge controller indicates the batteries are fully charged and is indicating "trickle charge".  So that seems to be working.

Also tried the inverter.  Plugged in a laptop power supply into the inverter, turned it on, and then turned on the laptop (took battery out of laptop).  - Laptop booted up fine.  So that seems to be working!

Won't use heavier loads until I get a breaker/fuse and more panels, figured testing a 50w laptop (4.1amps at 12v) would not pose too much of a risk with the 4 gauge cable.

Now if I make my system 30 times bigger, I can get off the grid!! lol

Thanks to all those who replied with help.
Patrick
 
163 Posts
Sep 9, 2008 11:19 am
Re: Small Solar System

230V ac is two phases of 115V that are 180 degrees out of phase to each other. A transformer will not solve the problem.
You could do it with two piggy backed inverters.
But you might find it cheaper to change the motor/pump.

Actually a 120/240 step-up transformer will work just fine. I have one (Outback X-240) running my 1HP well pump and 1HP pool pump.

If he opens the connection to the pump it is very likely that it has an option inside to be wired either for 240V or 120V. Note that 230V and 240V is within the same tolerance and can be used interchangeably.

My 1HP pumps use about 1200 watts when running (10 amps at 120V or 5 amps at 240V) with about one-and-a-half times that at start-up, so I would estimate that his 3/4HP pump would probably draw around 8 amps continuous at 120V or 80amps at 12V from the batteries.

As for the rest of the advice, I'm inclined to advise Patrick to go back to the drawing board. Perhaps he can get Canadian Tire to exchange those ten 15watt panels for a single 150watt panel or two 75watt panels. Those 15 watt panels were designed for trickle charging batteries and he will only give himself a headache trying to build a system 15 watts at a time.
 
20 Posts
Sep 9, 2008 11:35 am
Re: Small Solar System

Hey John, thanks.  I will see about getting a step up transformer.

The reason for the small panels to start was cost;

Canadian tire had these panels on sale at $69 each.  They also had a 30W panel for $329!!  And an 80w panel (biggest one they had) for $999!!

So I figured I could get 150w for $690, instead of paying $658 for 60 watts, or $999 for 80w.

 
163 Posts
Sep 9, 2008 12:09 pm
Re: Small Solar System

$4.60 per watt is not a bad price for less than 200 watts, but as your system expands you want to be sure that the panels you add on will have the same specs as the original panels otherwise you will need to add a new charge controller for each new type of panel that you add on to your system.

A 15 watt ungrounded panel is not much of a hazard when it is the only source of power, but when it is included into a system where power may be fed back to that panel in a fault situation then you have a problem because you are violating electrical codes that are in place for your own safety.
 
20 Posts
Sep 9, 2008 02:57 pm
Re: Small Solar System

How do I ground the solar panel(s)?  They are made of plastic....only thing coming out of them is a neg and pos wire...  Do I connect a ground to the neg wire?

I called Motomaster (maker of the Eliminator panels I bought) and they just said "you don't need to ground them"

Also - This grounding issue got me thinking, when my batteries are full, and the charge controller stops them from being charged, where does the electricity go?  It has what looks like a heat sink on it, so imagine it dissipates it through that in the form of heat, but what if it becomes too hot?  Panels are generating it, it's going into the charge controller, but then what happens to it if it's not being fed to the batteries?

« Last Edit: Sep 9, 2008 03:03 pm by Patrick Guenette »
 
163 Posts
Sep 9, 2008 05:25 pm
Re: Small Solar System

Patrick,

All of your negatives should be grounded.

The charge controller has the ability to turn your panels off if the batteries are full. However, there should be a breaker or fuse on the output of the solar panels going into the charge controller.
 
20 Posts
Sep 10, 2008 09:51 am
Re: Small Solar System

The company told me the solar panels had internal fuses for that.  (So good for safety I guess, but if the fuse ever goes off, guess my panels are garbage as there's no access to the insides).

So if I run a ground wire from the negative terminal of one of the batteries to the earth, that should be ok?  - Won't slowly drain power from the battery?

The batteries are hooked up to the inverter, with 4 gauge car battery cable (36 inches long), and the inverter itself had a ground port (which I grounded, about 24" into the earth).

So if I put a 200amp breaker one the positive cable from the battery to the inverter, and a ground from the negative cable, that should be good?

System is up and runs fine now (had 7.5 amps @12v generated in full sun yesterday afternoon), just want to make sure it's safe.

Called at least 5 electricians yesterday, and none of them wanted to come over to setup my system.  All said they don't do those types of jobs..too "small" for them lol

Thanks,
Patrick
 
163 Posts
Sep 10, 2008 11:05 am
Re: Small Solar System

Patrick,

It wouldn't hurt to run 3 feet of ground wire (the same size that you used from the inverter to the ground rod) from the inverter's ground to the negative terminal of the battery.

This will not drain your battery. In fact, your battery is probably grounded already through the inverter. To test this, put your voltmeter across the battery terminals and then move the negative lead of the meter to the ground of your inverter and you should read the same voltage.

Glad to hear that you are up and running, but 7.5A @ 12V is only 90 watts which is not so good if you consider that you paid for 150 watts of power. It might be due to bad connections on some of the panels since your are tying ten of them together, but more than likely it is just the tolerance on a 15 watt panel where they wouldn't give you the same guarantee as you would get with a larger panel.

John
 
20 Posts
Sep 10, 2008 11:17 am
Re: Small Solar System

Thanks, I will do that for the ground. 

So the fuse/breaker should go on the positive battery cable right?  I just cut the cable and strip the shielding and install the breaker in between right?

Since the batteries are in parallel, doesn't matter which positive cable I use right?

Thanks again for your help, and yes now that I have my first "test" array up and running, I'll be looking to buy real panels.

Is this a good panel?:

http://store.altenergystore.com/Solar-Panels/150-Watts-Up-Solar-Panels/GEPVp-200-200W-18V-Solar-Panel/p3843/

5 of these would give me 1kw right?

Thanks,
Patrick


 
163 Posts
Sep 10, 2008 11:57 am
Re: Small Solar System

Patrick,

In this field every question will lead to another and you never stop learning.

A 200 watt panel is generally much larger and heavier than a 100 watt panel, so where it will be mounted is one consideration. Will you be mounting the panels on your own, or will you have assistance? Is your roof steep or high? Do you feel comfortable taking a 40lb panel up onto the roof by yourself? etc. etc. etc.

Generally speaking, I would look for someone who had similar panels in a similar location. IE. same latitude, as some panels work better in hot climates than others.

I have Evergreen 120 watt "B" panels. The "B" indicates that they have blemishes but the same power output and the manufacturer will generally sell them for ten or fifteen percent less than the regular price.

Once you start increasing the power then voltage is also a consideration. I have a 48V system which means that a single Outback MX60 Charge Controller can accommodate 3200 watts of solar panels. If I had a 12V inverter then I would need four MX60 Charge Controllers for the same system.

Will your system be grid-tied or stand-alone? Will you want battery back-up? Answers to both of those questions can affect the decision on which PV panel and/or inverter you go with.

John
 
578 Posts
Sep 11, 2008 12:54 pm
Re: Small Solar System

the GE 200 were a good module.  i think we only have 1 or 2 left though.  i believe they have been discontinued, or perhaps are not available through common distribution anymore.
FYI -

james
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