New To Solar-Need Advice

[Dave Beleskey]

I am fairly new to the world or solar power. I have place in northern Ontario that we use only in the summer months. Everything I need runs off 12 volts, I have two 120 amp hour deep cell batteries and had a 55 watt solar panel setup with a 7 amp charge controller.

Last summer it didn't seem to charge enough for our needs and I had to run a generator to charge the batteries once in a while. I would like to get away from that if possible. From what I can tell, I am using about 60 ahrs per day...

My thoughts are to install a larger system, say 300 watts and a MPPT charge controller.

I am thinking a 300W GEN-2 Quasi-Crystal panel from Canadian Solar and a Phocos MPPT charge controller. Would I be better off with two smaller panels instead of one larger one ? A 20 or 30 amp controller ?

Any suggestions or advice would be great...Thanks

[Andy Rhody]

Dave, I can't answere most of your questions but I have a similar system that I set-up in an off-grid cabin this summer and am also gathering information. I'm also working around 300 watts but with the excetpion of a CB radio and a night light running off my 12 volt battery bank, I'm also using an inverter for a 120 Volt AC system. Running 3 25 watt CFL lights I could get about 3 hours of light but that was with two 8 year old car batteries. I've updated to two Walmart 105 amp hour batteries and expect better.

System:

Two 12 volt 30 watt solar panels in paralle lequaling 60 watts.

Morning Star "SUNLIGHT" 10 amp controller.
I chose this because it's specs stated that it opperated below zero F. and
I needed a controller that worked at 20 degrees below 0.

Morning Star "Sure Sine" inverter.
This inverter also opperates at low temps, is pure sine wave, is hard-wired
into the system, and can be left on all the time. I just need to hit a light
switch and it turns on. It works with a "stand-by mode" and only uses 450
miliamps. When there is draw of more that 8 watts, the inverter wakes up
starts working.

Two Walmart 105 amp hour Marine Batteries.

[Rob Beckers]

Hi Dave,

How "northern" is your place? With a location it's not too hard to calculate how much solar you would need to cover your use.

-RoB-

[Dave Beleskey]

Thanks for the reply guys...

Andy, the reason I was asking about one or two panels is that if I understand correctly, if you have say two 200 watt panels connected in series, you get 24 volts. If using a MPPT controller, it cuts the voltage to 12 volts and delivers twice the amps. Not sure if I got that right though...not sure if it makes sense to have one large panel or two smaller ones and not sure on the controllers either. Did a lot of reading and still unsure.

Rob, My place is near Burkes Falls...not too far north but wont have any power there for a couple more years. Its just travel trailer, all 12 volt lights and water pump.

Thanks for the help.

[Rob Beckers]

Dave, an MPPT controller will take a higher input Voltage (at a lower current) and convert it to a lower Voltage, battery Voltage in this case (at a higher current). The input Voltage just needs to be above the battery Voltage for this to work, and below the maximum input Voltage of the controller.

So, a single 300W 72-cell panel would work fine. Those run at about 30 - 40 Volt depending on temperature and light. For a 20A controller (Phocos CIS-MPPT 75/20) that 300W is about the maximum, going with more PV will make the controller regulate output current and clip output power (300W @ 15V is 20A).

On the down side, in particular for Canadian Solar panels, is that their 250W 60-cell panels are much cheaper since they haul those in from China, while the 300W ones are made in Ontario. Our prices are currently 78 ct/W for the 250W Chinese CSI panels, and 99 ct/W for the 300W Ontario CSI panels. Though for a single panel that's not the end of the world I suppose.

I've not looked at the map yet, a little short on time right now, to see what the yield is for a single 300W panel in your area. Will do so later.

-RoB-

[Dave Beleskey]

Hi Rob

Sorry for the delay on getting back to you..power supply on my Bell internet router gave up and it took them five days to get one to me. I could go on...

I was actually looking at the 300 watt panel and a 30 amp charge controller.

Do you have any brands that you would recommend ?
The Phocos MPPT charge controller was just suggested to me by the person I am getting the panel from... any recommendations would be appreciated.

Thanks
Dave

[Rob Beckers]

Dave, for a single 300W panel a 20A controller would be fine. During charging the battery Voltage is nearer to 15V, so 15 * 20 = 300 Watt into the batteries (and a 300W panel will rarely actually deliver 300W).

Have a look at the ET-Solar TRACER-2210RN, that's a 20A/12V MPPT controller, maximum 100V DC in. I like 'm, sold a bunch of 'm, and no complaints to date. They are about half the price of the Phocos ($144 plus shipping and tax if we were selling it).

-RoB-

[Dave Beleskey]

Thanks very much for your help Rob..

Sorry for all the questions but, I want to make as sure as I can that I get this right. It looks like a 20 amp MPPT controller would be running at its max for the 300 watt panel. If I wanted to add another panel after I get this running, it might not handle it ?

Is there any disadvantage to going with say a 45 amp controller ?
Had a look at your site but couldn't find any controllers listed. Was trying to figure out shipping costs to Barrie ON.

Dave

[Rob Beckers]

Dave, sorry for the delay in responding. I've been painting our new office (lots more to do!).

Yes, a 20A controller would be running at peak output with a 300W panel, if there's enough sun and the outside temperature is low enough to deliver that much to the controller.

For two panels or future expansion a 45A controller would be the better choice. There's no real disadvantage; a 45A controller is probably slightly less efficient running at low power levels but that won't make much of a difference. The obvious disadvantage is price: An EP Solar TRACER-4210RN (40A/100V no display) is $239, while an EP Solar ET4415N (45A/150V, with display) is $461, and those are the low-end of the brands. A Morningstar (top brand) TS-MPPT-45 without display is $497. Shipping to Barrie should be around $25 for a charge controller.

-RoB-

[Dave Beleskey]

Thanks Rob...

I actually found locally, it was on the board at our grocery store, an Outback MF60 new in the box. He wanted $500 got it for $480. From what I could find they are not a bad unit and usually sell upwards of $550.

Now I have a new issue...trying to figure out what wire to use to connect the panel to the controller and the controller to the batteries.

The panel will be located about 50' from the trailer in order to get sunlight. I was thinking about mounting the controller in the trailer in a storage area under the couch, lots of room and would be inside and will be able to read the display. It will be about 20' from the batteries.

Dave

[Ralph Day]

Hi Dave
If you're putting the controller under the seat box, make sure you have some venting...depending on the sun level and such the fan will need to run for some cooling of electronics. If your dc converter is in the same area it might well be vented already.

ralph

[Dave Beleskey]

Hi Ralph

Might have to rethink that...not much ventilation under there. It's actually where the fresh water tank is. The power converter for the trailer is under the sink area. Not a good option to mount there because it's hard to get at and wouldn't be able to read the display.

I originally thought about mounting it in the battery box that I built. It sits on the tongue of the trailer. It is ventilated but I was concerned about the controller being exposed more to the elements. The box doesn't leak but there would be more dampness and humidity for sure.

Dave

[Rob Beckers]

Dave, the Outback is a good unit. Congrats!
You will probably want to get a couple of MC4 connectors to connect to the panel(s) so you don't have to cut the connectors off. They can be soldered as well (normally they are crimped, but the crimpers we use are just a hair under $400), just fold the tabs over the wire first, then solder, then shove the whole assembly (wire plus metal pin) into the connector until it clicks in place.

We use wire that's marked "PV-wire" for all exposed wiring to the panels, code requires it, it has double the insulation thickness and is UV-proof (vs. regular wire). You can of course use other types, USE-2 was the type before the switch to PV-wire, and that's should be readily available from local home improvement stores.

-RoB-

[Dave Beleskey]

That's good to hear Rob...

I have tried to do some reading about wire size required and I just get more confused because there are several different answers. The wire I was looking to use is called OLFLEX SOLAR XLSv 10AWG. I have been seeing in different places that to run say 70' total, from panel to controller to batteries, that I need to use 4AWG, other places say 6AWG a couple have said 2AWG...
The OLFLEX 10AWG is $2.50 a meter. Don't want to under size the wire and have issues.
Dave

[Rob Beckers]

Dave, wire size depends on what you're hooking up and how far the run is (and code). How many panels are on there, and what configuration (panels per string, number of strings in parallel)?

-RoB-

[Dave Beleskey]

Rob, I will be using one Canadian Solar 300 Watt panel. The run from the panel to the MPPT charger will be between 35' and 40', can't see it being anymore. Too much snow to get in up there right now for a real accurate measurement. From the controller to the batteries about 6'. I do have a small 300 watt inverter that I might use every once in a while to charge my cordless drill battery. Other than that, everything else is direct 12 volts.

Dave

[Brian McGowan]

For what it's worth Dave, I charge my Milwaukee drill batteries with a Milwaukee charger that plugs into a cigarette lighter and I have a bunch of them tied to my battery system at various places throughout the house and at the batteries. Saves the inefficiency of the inverter. I do the same with my cell phones and AA and AAA batteries which I used in various things around the house.

From what I can tell that panel maxes out at 8.87 amps and around 36 volts so that is all you have to worry about getting to the charge controller. By my calculation the charge controller could supply about 25 amps to the battery under these conditions but I would mount the charge controller in the safest place as close to the battery as possible to keep the run between them as short as possible and use the biggest wire you can for that run. Rob can probably help with the rest. I have to run at this moment.

[Dave Beleskey]

Thanks Brian...that makes sense, I actually have an adapter that will go in cigarette lighter. I will use that as you suggested for the batteries if I need to then I can eliminate the inverter all together. I have three batteries I can bring charged from home anyway and will likely rarely if ever use the charger there.

As I mentioned, the wire I found is OLFEX solar wire but its 10 AWG. The guy that has the wire says that's enough for that panel as long as I don't go over 100'. That's certainly not what I read other places. Just want to be sure before I get it.
Dave

[Rob Beckers]

Dave, 10 AWG would be plenty!
Normal MPPT current for those panels is just 8.3A. At 40' of 10 AWG you'd have 6 Watt in losses, (or 1.9%) if that panel is running at full (peak) power, something that rarely happens. At 100' of 10 AWG you're looking at 14W in losses (4.8%).

-RoB-

[Dave Beleskey]

Excellent...thanks for all your help.