Help Me Choose A Charge Controller for My Somewhat Unusual Application

williaty · August 2012

I've been reading this forum for a couple of months now and just registered to ask a question that I can't find info on to resolve for myself. You guys have already provided enough information to define loads, calculate bank size, calculate array size for my insolation, etc. I'm just stuck on one point.

I have a somewhat unusual system in that it's going to be an emergency backup, not a constant-use system. Basically, the battery bank will sit most of the time connected to grid power to float it. If our ARES group gets deployed to someplace without power, the batteries, panels, controller, wiring, and associated crap will be carted off to wherever we've been deployed, used, and then put back into storage when the disaster is over. I know some of you are scratching your heads and wondering why we're not just using a generator. It comes down to the logistics of getting fuel and the RFI and audible noise created by one. So, the big thing here is that it's very difficult to predict what an "average" load for this system is. I can define an upper bound "worst case" limit (key-down 24/7) and a lower bound limit (receive only 24/7) for the equipment but predicting exactly where within that range any given day will fall is nearly impossible. If the station is the net control vs just a dispersed communications station, the Wh/day used could easily vary by a factor of 20.

Given that we're powering radio equipment, low RFI is the top priority. Only two controllers that I'm aware of have all the correct FCC and European certifications for this use. That means I'm choosing between the Morningstar TriStar TS-MPPT-60 and the Xantrex XW-MPPT60. I've read extensively about these two controllers, I've looked through their manuals, I've read reviews, etc. I have a clear picture of what the differences between them are and which features actually matter for our usage. I'm stuck on one point though: Absorption stage termination.

The Morningstar will go into Absorb every day and run out the timer. The Xantrex will terminate on Ending Amps. I see advantages and disadvantages to both methods for our use. While I've seen some clever hacks to make the MS Absorb time method work for things like weekend cabins, those cabins have a more consistent power use weekend-to-weekend than we will. I see the appeal to terminating on Ending Amps, but that could be easily thrown off by wither someone at the station has one of the radios turned on or off. Set it for the real termination point and turning on any of the radios will prevent it from terminating. Set it for the termination point plus the idle current of the radios and if someone turns off a radio, it'll terminate too soon.

In your experience, which method of charge termination is going to be more reliable in this usage case?

techntrek · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Not an answer to your final question, but I have a thought on the implied question farther up of how to size your system. Since you need 24/7 availability in emergency conditions (this isn't a hobby rig that can go down w/o consequence), you need to make sure you can supply for your worst-case scenario. With your no-RFI requirement that might at first seem like I'm saying you need enough batteries to handle key-down 24/7, but I have a lighter solution. I would determine your average need and size the battery bank and PV for that, then split the batteries and PV into two systems. Normally you would use them in parallel, but if you determine that you are key-down more than normal then you can split them up. Carry a 2 kw Honda inverter-genset to recharge one while you continue on the other. Carry a 20 gallon cache of gas and you would be able to go a very long time. You would only be using the fuel supply if you went above average during a mission, and only to cover the amount above average. The PV would still do most of the work.

Cariboocoot · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Welcome to the forum.

I think you should also look at the MidNite Classic controllers: http://www.solar-electric.com/misocl.html

My opinion: in this application you'd want either/or which means Absorb ends either when Amps drops below 'X' or if time climbs to 'Y'.
But cheer up: the number is not that critical in either case if you can monitor the battery with -ahem- a battery monitor. Since this won't be a "set-and-forget" install you'll be able to keep an eye on it and make sure it gets its full charge once in a while.

BB. · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

By the way, you can add Midnite for FCC Class B listed MPPT charge controllers.

You still can have issues depending on frequency range, layout of the solar panels through controllers, battery banks, etc. I would suggest, if you can, the first 10 feet of cable entering/leaving the Charge Controllers and AC Inverters (if used) be in metal conduit (or other shielding of some sort--braid/sock/etc.). After 10 feet, any additional shielding does not really matter too much.

I am not sure I would get too wrapped up in the details. Many folks will program 2 hours of absorb timer during summer and 6 hours during winter (i.e., the sun setting stops the charging). In any case, you have enough control to trim the system to that day's needs. I would suggest a Battery Monitor (Victron is another good brand) and people can very quickly and easily see the state of the battery bank at any time (specific gravity is still the gold standard, but it is messy and not even possible if sealed/AGM cells are used).

The killer for you is not knowing your daily loads. If you have a variation of 20:1 -- That may be as simple as a pair of 6 volt golf cart batteries to a ton of fork lift batteries. You do have to set a design goal/limit. Similar with solar panels twox 250 watt solar panels vs 40x 250 watt panels.

For a portable system, weight and size is going to be important. And deciding when you really need 50-100+ watts vs 2-5 watts with a good antenna system.

In the end, I think, you are going to be looking at a smaller set of batteries and solar panels (who is going to anchor 10kW of solar panels for a day or a week of use) and haul a ton of batteries for a "minor" effort.

I would add a Honda eu2000i (or 3000/1000 series) inverter generator with eco throttle control. You can run around 400 watts for 9+ hours on 1 gallon of fuel.

To compare, lets say you need 400 watts * 24 hours per day and use 3 gallons of fuel:

400 watts * 24 hours = 9,600 Watt*Hours

And lets say you want a 12 volt battery system that will run 1 day to 50% maximum discharge (for off grid use, we recommend around 1-3 days of "no sun" with 2 days being a nice balanced load/battery system for most people):

9,600 WH * 1/12 volts * 1 day no sun * 1/0.50 max discharge = 1,600 AH battery bank

A set of medium grade Trojan batteries:

Trojan L16RE-A 325 AH Deep Cycle Battery
Price: $306.00

You would need 2 in series * 5 parallel strings for (not that I would recommend this setup--just sizing for weight and costs):

10*$306 = $3,060 total cost
10*115 lbs each = 1,115 lbs.

To run 400 watts * 24 hours in a moderate climate of 4 hours of sun minimum (~9 months of the year), your solar panels needs would be:

400 watts * 24 hours per day * 1/0.77 charger+panel deratings * 1/0.80 battery losses * 1/4 hours of sun minimum per day = 3,896 watts of solar panels
3,896 watts of panel / 250 watt per panel = ~16 panels (~288 sq feet of solar array--note each panel needs to people to move safely if not pre-framed as part of trailer--for example).
47 lbs per panel * 16 = 752 lbs of solar panels (plus packing for transport, frame work, etc.).

Vs $1,000 for a Honda eu200i @ 57 lbs.

Fuel is ~6lbs per gallon (propane conversions available). 1,000 lbs of fuel / 6 lbs per gallon = 167 gallons of gasoline.

167 gallons / 3 gallons per day = ~56 days of operation before resupply.

Don't get me wrong, I am not trying to tell you one way or the other--And in fact, I would probably suggest a hybrid system (solar+battery+generator+fuel storage) to give you the "best" of both worlds.

You pick, for example, "full power" operation for first two weeks, then "low power" operation from solar only until the next supply drop--Or whatever meets your needs.

There are lots of issues--Batteries that last 5-8 years (if taken care of), vs rotating gasoline every 1 year (with fuel stabilizer) or perhaps a propane conversion (weight/cost of tanks, fuel availability, etc.) or even a small diesel system (and its fuel storage issues). A second backup genset (possibly alternate fuel)...

So--Just a quick review of an arbitrary power need and the math I would use as a first cut of sizing the system.

-Bill

Cariboocoot · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Probably we should also mention that when it comes to portability, generators are easy; solar panels are big hunks of glass.
Since this is going to be a "deployment" install I'd go for AGM batteries too, as flooded cells can have nasty accidents.

williaty · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

OK reading the answers given so far, two main things stand out to me:

1) Which MPPT controller with the correct certifications can terminate off of EA *or* Max Time? You're right, that sounds like the best solution to the problem.

2) Generators are really a non-starter for this use. The traditional generators are fuel monsters. We've proved that ourselves at multiple events. The new inverter generators aren't always that simple either as they're all TERRIBLE sources of RFI and you end up having to take significant remedial steps to shut them up. ARRL just published a study on this in the last couple of months. While genny+fuel+filters is cheaper overall, a major concern for this is continuing to operate even under conditions when getting fuel isn't as simple as driving to the corner Stop-N-Go and we're not a priority for governmental fuel delivery.

BB. · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Then it gets back to how many Amp Hours or Watt Hours per day you need and how many hours of sun per day will you get.
-Bill

williaty · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

BB. wrote: »

Then it gets back to how many Amp Hours or Watt Hours per day you need and how many hours of sun per day will you get.
-Bill

Which is math I've already gone through. My question was specifically about picking a charge controller since one of the main differentiating features between them is how they terminate the absorb stage.

BB. · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

One thing I would suggest is going to the Midnite forum and asking there about the details regarding charge termination.

We have boB and halfcrazy (Ryan) posting here fairly often from Midnite--But you will probably get faster/deeper discussions there about their controllers.

Also--At this point, it would seem that Midnite has one of the more active controller software development projects right now--So if there is something "missing" that would better support your needs, you might have a good chance of getting it incorporated in a future release.

-Bill

westbranch · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

realizing you have to travel light and fast overlays a lot of constraints, so in order to help you find a working solution we really DO need to see your numbers, batt amp hrs, loads over the entire working day, PV array size, etc, etc not only the 'math' you did to decide just how big (or small) your install has to be. The full picture will give us a much better chance of working with you to a successful outcome.

thanks.

westbranch · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

see post #4

http://midnitesolar.com/smf_forum/index.php?topic=685.msg4458#new

vtmaps · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Midnite is coming on strong. I expect that their products will someday outshine the others, but at this moment Outback has mature products that do end amps very well. Their flexnet DC battery monitor allows their chargers and controllers to implement end amps charging. --vtMaps

Vic · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

But, vt,

To the best of my knowledge RE Outback FM Charge Controllers;

They are NOT FCC B,
Firmware updates REQUIRE sending the CC back to WA,
The OB Bat Mon -- FNDC -- requires another box, The Mate3

The OB CC does have End Amp funcrtion in the CC, which may well be good enough for this application.

The Midnite Classic is the Hot ticket IMHO. The Classic does have EA in the CC, and FW updates use the built-in USB, and perhaps also the built-in EtherNet interface. The very capable MNGP -- the CC Control Panel is removable for more convenient control and monitoring. MN has monitoring Apps that enhance the monitoring and dispaly of data .. and so on This is the best set of CCs available today for PV string voltages up to about 200 VDC. And as BB Bill noted, the MN Tech Support and Engineering folks are fairly active here, and frequent the MN Forum. I have not ever seen this level of great support from ANY other company.

In general, agree with those who note that having a Honda EU-1000 or larger Inverter genset (or perhaos another Inverter Genset) iis probably needed as a backup should be very strongly considered.

These Inverter gensets DO create a lot of HASH on the lower HF bands -- 160 and 80 Meters in particular. This can be filtered fairly easily, and the AC runs from the genset to loads can be run in metal conduit.

I do not know the scope of your ARES operations, but, often HF is not used, excpet for massive, large scale/long duration incedents. The bulk of the ARES events tha tI've seen used VHF/UHF FM radios, many HTs and some Base/Mobile FM boxes (and perhaps a repeater of two), which are much more immune to CC switching noises. As noted, siting antennas away from noise generating sources helps a great deal.

This detailed thread addresses some of the issues with reduction of CC RF noise:
http://forum.solar-electric.com/showthread.php?5887-Radio-Noise-from-PV-System

Some of us with Midnite Classic CCs have been asking for an EA function that uses a Shunt in the negative battery lead. THis could measure the actual battery charging current. This could be via a Batt Mon, some other hardware, or, perhaps some inferrance detected in the Classic's firmware -- stay tuned.

If it were my system, I'd use some PV + A Classic 150 CC + AGMs + a Honda EU genset for backup + an AC/ DC charger and some gasoline.

EDIT: Recently, Midnite added to the Classic CC line, with the Classic Lite, which replaces the LCB Graphics Panel with LEDs and PB switches - reduces cost by abt $110.:
http://www.solar-electric.com/misoclli.html

The MN Classic User's Manual:
http://midnitesolar.com/pdfs/classicManual.pdf

I am very Pro Midnite, as they do a teriffic job with their products, and their support is by far the best in the business. I have no affiliation with Midnite, just another satisfied customer.

I have had VERY POOR performance from the XW SCC (mppt 60-150, or whatever Schneider is calling it this week). Very BUGGY Firmware, that Schneider has been unwilling to fix, unless I PAY to rent the Implanter Tool (which I refuse to do to update the BUGGY FW that cane in that unit). Avoid this/their products like the plague that they are, is you possibly can. Vic

techntrek · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

williaty wrote: »

... a major concern for this is continuing to operate even under conditions when getting fuel isn't as simple as driving to the corner Stop-N-Go and we're not a priority for governmental fuel delivery.

Thus my suggestion to create a split system so the batteries being charged aren't part of the system currently driving your rigs. Then you can either move the batteries to be charged far away from your rigs or run a long line from the genset - and stick the genset inside a Faraday.

Vic · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

tnt,

Re the Faraday cage, by far the largest emissions from any of this stuff is Line-Conducted. I doubt than very, very little is Radiated from the genset.

And an additional note regarding HF Transceivers that run directly from "12 V" power. Many of them perform poorly from batteries that are not under charge. A fully charged LA battery rests at about 12.75-ish volts at nominal 77-ish degrees F. The voltage sags under load to 12.5 or below, even for a fully charged batt. These radios are speced at about 13.8 VDC to meet rated power, IMD etc. Running from a 120 VAC to 13.8 VDC supply is often required unless one is running QRP (low power), from my own experience. Different HF radios perform differently, naturally.

Experiences at Field Day are often quite a lot different than at Emeregency Drills or incedents, as HF is often not a large factor in the mjority of communications, at lthese drills/incedents in my experience. And, VHF/UHF Base/Mobile (50-80 watt radios) seem to handle direct battery operation quite a bit better than most HF radios. YMMV, Vic

SolarMusher · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

vtmaps wrote: »

Midnite is coming on strong. I expect that their products will someday outshine the others, but at this moment Outback has mature products that do end amps very well. Their flexnet DC battery monitor allows their chargers and controllers to implement end amps charging. --vtMaps

Vt,
Midnite is already outshining the others. Ea is working very well on Classic CC and you can run it with a standalone Battery Monitor if you need very accurate settings.
Another thing, everyone seems to forget when talking about EA and loads is that even when used without batt monitor, Absorb time could easily stop overcharging if correctly tuned. But you're right, Outback CC + Mate + Hub + FNDC will do the job (maybe one or two items missing, not sure).
I support Vic who support Midnite

Erik

williaty · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

We use VHF/UHF for inside-the-county communication. We use HF for state-wide. You guys might not need to worry about RFI for HF, but I do.

The Midnight stuff does look VERY interesting and, unless I find some problem with it, I think that's what I'll be getting. It worries me that it only has FCC certification and not the stricter CE cert, though.

vtmaps · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

SolarMusher wrote: »

Vt,
Ea is working very well on Classic CC and you can run it with a standalone Battery Monitor if you need very accurate settings.

Erik, are you saying that the Classic can read a battery monitor and, regardless of loads, know what the charging current is? The Outback can.

Midnite is already outshining the others.

No argument there. But they are not (yet) as mature a product line as Outback.

--vtMaps

Vic · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

williaty,

My perspective is 100% HF. The two off-grid sites here are exclusively developed for HF comms ... well 99.9998% in reality.

The reason for developing these sites is to leave the NOISEs of Urban density behind. On 75/80 Meters, the noise level iis S0 for local noise, altho, band noise/lightning "static" can be significant, and, rarely there is some propagated Line Loise..

It is possible to reduce Inverter, CC & inverter genset noise to almost undetectable levels. The largest noise sources are really TSW Inverters, but tradidional suppression and shielding works very well. BTW, I had thought that CE is self-certified (and therefore to me suspect ... dunno). 73, Vic

BB. · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Morning Star makes some pwm controllers with a slow clock option switch. This was intended for reducing audio noise on telecom systems... May work for HF radio work if you can use a simple controller.

-Bill

boB · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

williaty wrote: »

We use VHF/UHF for inside-the-county communication. We use HF for state-wide. You guys might not need to worry about RFI for HF, but I do.

The Midnight stuff does look VERY interesting and, unless I find some problem with it, I think that's what I'll be getting. It worries me that it only has FCC certification and not the stricter CE cert, though.

The MidNite Classic actually does have CE certification. Neither one, FCC or CE involves anything below 30 MHz for a charge controller though.

To pass the CE, it will require some common mode ferrites on all 4 in/out wires, but that was only to reduce some 40 MHz spikes somewhat
above the allowable line limit in that area of the spectrum. It's pretty quiet in the VHF and UHF spectrum. As far as HF goes, it's fairly quiet too,
but not zero.

I backed up my HF mobile to the PV solar array with Classic running in our small parking lot and there was some noise there but the noise was pretty much
nonexistent on the opposite side of the parking lot.

boB

williaty · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Good data, thanks.

I'm pretty well sold on the Midnite Classic now. Seems to be the most features that are relevant to my interests plus I'm always more comfortable going with a company with continuing development in response to user concerns.

SolarMusher · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

vtmaps wrote: »

Erik, are you saying that the Classic can read a battery monitor and, regardless of loads, know what the charging current is? The Outback can.

No argument there. But they are not (yet) as mature a product line as Outback.

--vtMaps

Vt, I'm just talking about what I'm living everyday...
One don't always need an expensive solution such Outback to charge and control batteries.
Vic had already tried to explain it in several posts and I think he's right.
1) A single bat monitor could show you the end amps for your battery bank, right? Knowing that one can set his Classic EA taking account of his loads.
2) If these loads (amps and time) are higher than planned, time of Absorb might be too long and could result in overcharge, right?
3) With an Absorb Time scheduled to x hours corresponding to your average DOD as secondary setting, (one can easily find the right value for a given DOD, just to read counter it in his CC).
4) Tell me how a battery could overcharge and where Outback is more mature? Is Outback more mature when they need two inverters to make 240VAC? Personnaly, I'm 2-3A positive on battery monitor at the end of the day with 830AH/48V.
5) I didn't tell you that you was wrong with an Outback solution, I'm just trying to explain that one could control it as well with a Classic + a Battery Monitor for far less money.
Erik

Cariboocoot · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

The Outback's Flexnet monitoring system can look at the current going in to a battery and coming out of a battery separately - using two shunts. It's more accurate, but it's also more money. This is not a hyper-critical adjustment, guys; don't make it out to be one.

Outback's Radian is 240 output. Their other inverters can be 240 with an autotransformer. The equipment has been around a while and is proven technology, designed to be adaptable to many varied applications. That doesn't make it ideal for every application, however.

Before you try to compare Outback to MidNite remember MidNite doesn't make inverters (yet) and the guys who design the MidNite stuff used to design the Outback stuff. In that respect, the Classic is "the latest version" of the MX/FM controllers.

No "brand-name slug fests" here, okay?

stephendv · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

SolarMusher wrote: »

1) A single bat monitor could show you the end amps for your battery bank, right? Knowing that one can set his Classic EA taking account of his loads.
2) If these loads (amps and time) are higher than planned, time of Absorb might be too long and could result in overcharge, right?

Mmmmm, yeah sort of a cludge but you have to admit that using the flexnet system would mean that it gets the end amps 100% right every time. Without knowing how much current is going to the battery the midnite (or Xantrex XW for that matter) will always be making a bit of a guess. It's definitely better than a fixed time, but worse than the flexnet DC solution.

What would be nice is if the midnite could be told to end absorb through an external signal, e.g. ethernet or serial. That would provide an open solution so that you could rig a battery monitor to tell it to stop absorb. ...that would give midnite some breathing space while they work on a flexnet dc competitor

vtmaps · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

stephendv wrote: »

What would be nice is if the midnite could be told to end absorb....

Nicer still would be for the midnite to come with a SG probe that could end absorb at a user configurable SG :cool:

SolarMusher wrote:

Vt, I'm just talking about what I'm living everyday...
One don't always need an expensive solution such Outback to charge and control batteries.

I am also living that every day. I do not have a Flexnet DC. I use time to end absorb charge. End amps doesn't work for me. My target end amps would be 3.5 amps and I have loads (fridge and freezer) turning on and off that are larger than that.

My 'absorb time' approach works pretty well if I start the day at about 85% SOC. If I start the day too much below that I will undercharge my batteries (unless I manually extend the absorb time). I also have to make seasonal adjustments to the absorb time to keep the batteries happy. My wife barely understands our off-grid system. I told her to get a flexnet DC if I die. :roll:

--vtMaps

mtdoc · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

I have and use a Flexnet DC with Outback inverter and Midnite Classic CC. They all work great together

When in grid-tie mode the FNDC end amp function works well to control and initiate Selling only when batteries are fully charged and this keeps the Midnite CC in bulk mode, preventing it from going to float so that max amps are passed through from PV-->batteries-->GVFX-->grid.

I realize this scenario is not relevant to the OPs but it does illustrate how the FNDC end amp function can work in well with a system using a Midnite CC.

stephendv wrote:

What would be nice is if the midnite could be told to end absorb through an external signal, e.g. ethernet or serial. That would provide an open solution so that you could rig a battery monitor to tell it to stop absorb. ...that would give midnite some breathing space while they work on a flexnet dc competitor

What would be nice would be if while in off grid mode, the FNDCs Aux ports could be used to trigger an ending of absorption in the Midnite CC based on FNDC measured end amps.

westbranch · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Williaty, the Classic line is essentially "hot off the presses" and is really still under construction.
There are/were a lot of us waiting for ~ 2 years for the release, it finally came and since then they have just kept making the Classic 'sit up and do more tricks'... it boggles the mind
.... JMHO

boB · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Battery current in/out necessity duly noted. We are addressing this...

The "Whizbang 1000" will do as requested and tons more for about half the price of an FNDC.

Look for the WB1K in about 6 to 8 months or so. This will be for techno junkies on steroids.

As for being mature, we will never grow up !

boB

Photowhit · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

boB, ...you on a bathroom break again!

Looks like actually having 3 Classic's all with different array's might become a reality for me! So that Master and slave feature would be really nice. I might be a good test subject by next summer, 1st pair of CC should go in in a couple months....

Let me know where to send the pizza.

silvertop · August 2012

Re: Help Me Choose A Charge Controller for My Somewhat Unusual Application

Just my two cents.... I have been running 3 XW MPPT60-150 off grid. They have the capacity to run off end amps AND an Absorbtion timer simultaneously, that I set for 180 minutes in the summer, longer in the winter. I'm very happy with these controllers and I would recommend them. I do not run a system control panel because I am off grid but run them as one unit ( a nice feature) with a cat 5e cable between each controller, and monitor my system with my Tri-Metric 2025A. All other data that I need Is displayed individually , or as ONE controler on their displays. I don't know what bugs others might have had, but I suspect that they might be related to the system control panel that is only needed, in my opinion, if you grid tie. I question the necessity of this between controllers ; all 3 charge individually but enter bulk/absorb/ float together I have not had any bugs......:cool:

Help Me Choose A Charge Controller for My Somewhat Unusual Application

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