Solar panel users--

[foggysail]

I am surprised at a couple of things about your current system:

1. That the 30A PWM controller hasn't burned out yet. 4 x 150 watt panels should produce about 33 amps. You are right on the edge, but the real reason is probably #2.

2. The maximum of 24 amps is way low. See #1. Maybe the wire is too small. That would be the one thing that could easily explain the low amperage.

With a good MPPT controller, you should get 40 amps to your batteries.

David

Dave-- each set of twos has separate #10 wires including returns to the controller. I worried when I first put the system together about voltage drops and ran the wire losses at the time which is insignificant.

No doubt about what I should get here. In my hunt for various MPPT controllers earlier today, I restricted my search to 40+ ampere devices. We will soon know if the pulse width modulation controller is (by then was) the problem. Twistedtree has a great controller with some size restrictions along with a $500+ price tag. My goal is to keep my purchase cost around $300 or so for a Victron 100/50. I won't order it (or something else) before next week. Just tooo busy trying to finish doing over all my canvas, taking care of our apartments plus some work that needs to get done on my home.

I'd probably make the changes one step at a time and see how you make out. So first, rewire the existing panels in series and install an MPPT controller, and see how it does.

You might also find it useful to check the power consumption of your loads. LED TVs over the past few years with Energy Star ratings are pretty good, but older LCD tvs use a lot more power, and some older ones continue to draw close to the same amount of power when turned off as when turned on. And I presume you have converted your lights to LED bulbs? They make a big difference too, even over compact florescent.

Sure enough-- all bulbs are LED but consumption is not the issue as we discuss the meager output from my panels. Your suggestion is right on the mark--- take one thing at a time. I will post next week which controller I go with and certainly will provide a performance report to see if the limited DC output improves a lot with MPPT. OH still open for suggestions for controllers. Some such as your Outback won't work with an 18V panel unless there is a minimum of two in series.

Also noticed there is an ongoing discussion over at Cruisers on this very topic.

 

[twistedtree]

Be sure you understand what's needed to program the Victron charge controller. A lot of their stuff requires a special interface adapter and software to program it, so be sure to factor that into the cost.

 

[Insequent]

Both Outback and Victron make very good controllers. I have 2 Outback 80 units (and 2070 W of panels) and have seen over the rated/limited total capacity of 160A charge rate.

I agree with Twisted - take one step at a time so you clearly see the benefit/impact. My main reason for posting is to suggest you give yourself some headroom for future expansion. Think ahead as far as possible. At present you could add more poly panels as a second step. Thats fine, but where you will likely end up in the future is replacing them (sell the old poly's) with some high efficiency mono-panels to better utilise the real estate available. Once you know you have very convenient charging you add demand to the system, increase the size of the house bank, and luxuriate in the convenience and flexibility. No more 'well I wont have a coffee because it is not worth starting the genny'.

 

[foggysail]

I have given thought to replacing the polys and for sure, monos are better panels. But they are there and they do work. So the first thing I plan to do is replace my Morningstar Pro 30 controller with an MPPT to maximize the little output these panels can provide.

Now my hangup!!! Yes, I do plan to purchase a controller with 50+ amperes capability. And yes the Outback (TwistedTree's for example) are huge compared to that provided by Victron's BlueSolar. Space here on my boat is critical as I am sure it is for others on their boats. The Outback that is 16" tall is a hard swallow compared to BlueSolar 100/50. Are there other quality controllers that compete with the Outback and Victron?

Twisted mentioned the programming along with the added cost for their dongle. First cost, I hoped to constrain spending to around $300 BUT if necessary I will not hesitate to reach upwards into the $500+ range. I just want to do this right and not have to redo it again later.

I mentioned earlier that I had added an new hardtop to cover our helm. This addition does provide real estate for additional panels if I later desire to up my available amperage. I could even do this without mucking with my system as it is now. I do however really want to venture into MPPT land.

 

[DavidM]

Your voltage drop with two parallel 10 ga circuits to handle 24A (measured) maximum current is not insignificant. Plugging 12A, 40' round trip length, 10 ga wire into my calculator I get 0.5 V drop.

If you use the 35 A that the panels are capable of, you get a .73 V drop and maybe more if the length is longer.

So, I would say that your wire size could be contributing to the low current you are measuring. But at least it may have saved your 30A PWM controller ;-).

Go with the MPPT controller and see what you get. Consider running 4 parallel 10 gauge circuits to the panels.

David

 

[foggysail]

Your voltage drop with two parallel 10 ga circuits to handle 24A (measured) maximum current is not insignificant. Plugging 12A, 40' round trip length, 10 ga wire into my calculator I get 0.5 V drop.

If you use the 35 A that the panels are capable of, you get a .73 V drop and maybe more if the length is longer.

So, I would say that your wire size could be contributing to the low current you are measuring. But at least it may have saved your 30A PWM controller ;-).

Go with the MPPT controller and see what you get. Consider running 4 parallel 10 gauge circuits to the panels.

David

I do not think wiring drop has any bearing on my system's current performance. To my knowledge, the MorningStar Pro 30 lacks a buck converter so the input voltage (and I haven't measured it) should be essentially the battery voltage plus any circuit drop in the controller.

That is not the case however if my controller is an MPPT. MOre to think about is when the batteries are more acceptable to charge current, their terminal voltages are low, lower than that of float. So as the batteries accept charge and their terminal voltage increases, there is less current into the controller resulting a lower wire drop.

One last consideration for improvement. There is nothing wrong nor impeding my re-wiring all four panels into a series circuit instead of parallel.

EDIT:

Dave-- you're right on suggesting doing nothing more than changing the controller to MPPT and see what happens. That I my current plan and if necessary....such as using an Outback, I would have to series because they require a minimum voltage above the battery voltage. I remember seeing this in their specification data. I do think a series connection is in my future

 

[twistedtree]

Foggysail, you said something earlier about the Outback requiring a high input voltage. I hadn't heard that before, so did some checking. I found a tech note on their site about array sizing and they say the min input voltage is 2V more than the battery voltage. So I think you have a lot of flexibility is how you configure your array.

I also took a quick look at the Victron BlueSolar MPPT 100/30. To configure it beyond the pre-set voltages, you need to buy a USB or bluetooth dongle and use their software to configure. They also have a note that input voltage must be 5V higher than the battery voltage for the controller to start. And another note that despite the 100V allowed input in the product's name, any input voltage over 80V causes the device to limit power. So it's really an 80/30, not a 100/30.

So the Victron is definitely less expensive, but a lot less capable. But it still might be a good fit for your application.

 

[twistedtree]

Oh, and I forgot to mention that the Victron does battery temp sensing at the controller which is a bit odd. So the controller needs to be mounted in very close proximity to the batteries to get any reasonable temp reading. Otherwise the temp compensation won't work. The Outback uses a remote probe that sticks to the side of the battery.

If your batteries are in the ER, or other space that gets hot, temp compensation is pretty important.

 

[foggysail]

Foggysail, you said something earlier about the Outback requiring a high input voltage. I hadn't heard that before, so did some checking. I found a tech note on their site about array sizing and they say the min input voltage is 2V more than the battery voltage. So I think you have a lot of flexibility is how you configure your array.

I also took a quick look at the Victron BlueSolar MPPT 100/30. To configure it beyond the pre-set voltages, you need to buy a USB or bluetooth dongle and use their software to configure. They also have a note that input voltage must be 5V higher than the battery voltage for the controller to start. And another note that despite the 100V allowed input in the product's name, any input voltage over 80V causes the device to limit power. So it's really an 80/30, not a 100/30.

So the Victron is definitely less expensive, but a lot less capable. But it still might be a good fit for your application.

Gees Twisted, I have scanned so many different data sheets in the last couple of days, I must have seen numbers for these requirements on a different controller. So although I get more options with Outback because essentially there is not 'head' voltage to requirement, and I also have looked again at their specifications, I intend to break my 4 panels into two sets of two in series/parallel AFTER I establish a performance baseline between MPPT and the pulse width controller that is now in the system.

Dave (djmarchand) is correct about cabling losses impacting total performance but as I see it, the problem only applies to MPPT. Next week when I am at my boat, I intend to measure the panel voltage at the controller where I expect it to be slightly over the battery voltage.

My only hesitation to immediately go forward with the Outback is the package size compared to the Vitron. Will look into mounting opportunities next week.

 

[twistedtree]

The Victron may still be the best value/fit for you. I'm not trying to push Outback, even though that's what I've got. I just want to be sure you have as much accurate info as you can get. A heavily swaying factor for me was that I already had Outback inverters and a remote panel on my dash. All I had to do was plug in the charger and I gained remote control, and shared battery temp monitoring with the inverters.

Having to mount the Victron controller near the batteries seems like a pain to me, but it depends very much on the layout and existing wiring in your boat. They also have several other higher-end models, and I'll bet some have remove temp monitoring and might preserve smaller packaging.

 

[DavidM]

I will say this one last time and will not return to this silly thread: A 30 amp MPPT controller is too small for four 150w panels properly installed.

David

 

[kev_rm]

I will say this one last time and will not return to this silly thread: A 30 amp MPPT controller is too small for four 150w panels properly installed.

David

??? a 12V system?

did someone seriously suggest using 30A controller with 50A of input?

edit: oh wait never mind its foggy sail with his MTTP controllers.

 

[foggysail]

I will say this one last time and will not return to this silly thread: A 30 amp MPPT controller is too small for four 150w panels properly installed.

David

Don't get excited Dave, I made it clear earlier that I was looking at controllers whose capacity is greater than 40 amperes. You were/are correct, my current panels should provide greater output than 24 amperes. This thread was a great leaning tool for me as I prepare to improve my system to which you contributed valued information and shared experience.

The world of controllers has greatly improved in quality along with lower costs since I first installed what is now on my boat. I am about to make changes and I do not want to look back later and think "gees, I wish I had thought of that before..........."

 

[JDCAVE]

Morningstar produces two product lines that should work:
http://www.morningstarcorp.com/products/tristar-mppt/

http://www.morningstarcorp.com/product_category/mppt-charge-controllers/

They are highly regarded.

I had considered the Prostar line because of their smaller footprint.

Jim

 

[foggysail]

Morningstar produces two product lines that should work:
TriStar MPPT - Morningstar Corporation

MPPT Charge Controllers Archives - Morningstar Corporation

They are highly regarded.

I had considered the Prostar line because of their smaller footprint.

Jim

Thank you Jim for taking time to make your excellent suggestions. I am familiar with MorningStar, my current controller is their Pro 30 PWM controller.

I spent some effort trying to get facts so I could weigh my options for both my current need and future system growth. I have concentrated my attention after yesterday with Victron's 150-85 BlueSolar charge controller with the display.

Finding it at an affordable cost was difficult. I just sent a message to a seller on EBay who is offering this product for $688 to confirm his product is as pictured. If I get a commitment from him, I plan to make the purchase and put this exercise behind me. Sure..... it will be overkill with my puny 4 each 150 watt panels. But at least I will not find my self controller limited if I add capacity.

TwistedTree and Dave (djmarchand) suffered some agony trying their best to help. I really, really appreciate not only their effort but all those who offered suggestions. I just want to do it right this second time around.

Thank you again--