solar + batteris

Slownsy wrote:
It seams ther is as manny different opinions as peaple out there.

"Options", not "opinions" :). There are different ways to use what you have. And different scenarios of use.

Normally, people with this type of controller are trying to keep a safety margin, so that panels won't generate more current than controller could handle. It can get too hot, and controller will fail under 30A load. "Probably" with 3 panels you won't exceed the 30A limit, with dust on panels and losses in wires. Or it can get too cold and/or you camp at high altitudes and panel current will spike. Too many "ifs" to my taste. The manual does say "May be safely used with panels up to 60A, however charging current will be reduced to protect charger". A 30 PWM controller with built-in 100% safety margin? Not 20%? Maybe. Can't say. You are one of very few people that bought this controller.

You can't have 4 panels without getting a bigger controller. Again, "normally", people are trying to get a margin here as well, installing a bigger controller and beefier cables than their array requires, with possible extra panels in mind. Adding a 2nd controller and separate parallel set of wires will be a royal pain in the ars.

Hi all thanks for the input, special thanks to grizzzman, I have read what the instructions mention and was planing to contact Bogart but you saved me the trouble, will go ahead with the 3 panels for now and se what controler tels me with only the 3 my cable run to my breaker only about 10' and will use 6AVG from ther and to controler and 2 AVG to batteries,and maybe instal last panel with sepret controler later.
It seams ther is as manny different opinions as peaple out there.
Frank.

jrnymn7 wrote:
I wouldn't go with 24v panels at anything less than 460w, flat mounted, myself. Which is probably pretty close to what a 12v 300w pointed array would do.

Yes and no. In mid-summer the difference in harvest between flat and tilted is ~30% or less, so 300W tilted will harvest less than 460W flat. Besides, tilt is usually to one side only, and you don't always park with that side to the South. In Southern states I would say 300W tilt-able will collect less than 460W flat. In winter titled 300 could beat 460 flat, especially up North.

24V panels start at ~180W, so a pair of them would be pretty much +400W. With size (and often price too) of 200W panel being the same as 250W, and MPPT controllers being tolerable to current over its rated limit, it indeed makes makes sense to max it up to 480-500W.

Roof-mounted tilt-able and point-able arrays have fallen out of favor lately, with panel prices low. Especially point-able, i.e. with adjustable azimuth - too complicated, and a pain climbing up and down.

I wouldn't go with 24v panels at anything less than 460w, flat mounted, myself. Which is probably pretty close to what a 12v 300w pointed array would do.

My only concern about exceeding any controller's current rating, would be the heat being generated by doing it. Additional ventilation would now be required; perhaps even more-so with the larger units available, like say 45 amps and up.

jrnymn7 wrote:

At a 30 degree angle of incidence, the 4 panels can still put out about 90% of their Isc. At 45 degrees, about 80%. That's over 32a, and about 29a, respectively. So using all 4 panels is too much.

That's why for +300W I prefer 24V panels and MPPT controller. Most users do, I think. No worries about exceeding the controller current rating, and parallel wiring becomes optional.

BFL said,

"A panel will do its Isc (ignore the lower amp Imp for MPPT) at STC when the panel is aimed at the sun. So how much less you get when the panel is flat depends on how high the sun gets where you are at what time of year.

You can be far enough South in the summer that your flat panel will hit its full Isc rating."

At a 30 degree angle of incidence, the 4 panels can still put out about 90% of their Isc. At 45 degrees, about 80%. That's over 32a, and about 29a, respectively. So using all 4 panels is too much.

jrnymn7 wrote:
OP, if you're set on using the 30a trimetric controller, then install 3 panels flat, run that 8ga on both sides of the controller, for some intentionally engineered efficiency loss / voltage drop,

Yep. 3 is less than 4, but since he insists on having less power...
Before controller, in this case, I would run MC4 AWG 8. With MC4 Y-splitters. No messy rooftop junction boxes.

smkettner wrote:
The monitor will tell the controller when the battery is full. This allows for automatic extended absorption time during heavy use and very short absorption when in storage or light use. No sense in having the battery at 14.8 volts three hours every day when in storage. Like wise some controllers drop to float as soon as they hit the voltage set point and will be a bit weak while in use.

Crutches. Using another device to help this one to work properly.

I have a current-based end of absorption on my controller. Heavy use - high current - absorption extends until heavy use is over. Light use - low current - absorption ends sooner. And simultaneously there is a timer-based absorption end, to end the struggle if it drags too long. Timer overrides the current-based end, i.e. when timer expires, absorption ends no matter what. Timer is adjustable too, of course. Very flexible firmware.

Slownsy wrote:
Ok tanks all yes I ment 4/150Watt panels, only planed on getting 2 but as I now have the 4 and the room for them, someone mentinned that the trimatik wood handle the extre load ok as they will be mounted flat and properly newer reach ther full potential, they are Renogy 150 W mono crystalline.
I can go to larger wier and stay with 3 panels if this what most recommend and try to sell last panel.
Frank.

Hi Frank
It is good to get advice on what to do but remember no one here has said "I have one and this is what it will do". Look at your manuel, it states that it will handle 4 135 watt panels. Thats 540 watts. In the specs page it states " Solar-panel peak current max 31 amps for peak efficiency. May be safely used with panels up to 60 amps, however charging current will be reduced to protect the charger".

With that being said here is an E-Mail reply from Ralph Hiesey the founder and owner of Bogart Engineering earlier this month that i feel applies.

Hello again, Miles
We intend to get a graph of the temp comp on the website soon. I have included an attatchment of this in the e-mail. I agree we need to make this easily accessible.

Even at 30 amps the heat sink should be ok up to 130F or so (ambient environment). Keeping it cooler would be better for longest life, however.(the temperature of the regulating transistors on the heat sink is of no concern-but the electrolytic capacitors on the pc board at high temperature could suffer in the long term) But if you are running 20 amps or less of panels it would be difficult to ever get it too hot. If at or over the 30 amps maximum try to insure the ambient temp is less then 120F. (Of course if over 31 amps the charger will reduce its output to protect itself-but will get hot)

Yours truly
Ralph H.

As you can see you could "overpanel" but you would have to be "VERY" careful with thermo management or you will shorten the life or kill the controller.
I personaly would not have a problem with running 3 panels on this controller.
Your 8AWG wire is just plain to small. Again look at the manuel i have already given my wiring recomendation in a previous post. Use the 8AWG wire on the single panel and pick up a cheap controller, problem solved :)