Multiple controllers?

[pmaru77]

Is ther anything wrong with having one controller per panel? This pertains to having 2 50W panels and a controller on each. The controllers are the same and the panels are the same. Why do this? Because I have them. And if a controller goes bad, the other panel/controller may keep me going. We are talking about a 20 dollar state of the art controller rated for 120w max panel. (8 Amp @ 12v) Plus I can see if the indicator lights on the controllers react equally when charging or fully charged etc.

One thing that may be a no no is that some controllers pulse the charge into the batteries, and the 2 chargers will be pulsing at different times.


More about controllers. Like what happens to the extra electricity once the batteries are all charged up. I'm guessing nuthin' , as these controllers are plastic cases with a board in them....and no heat sinking that I know of. So do they just put the panels in "neutral"? I'm sure there is a better technical connotation for the state of the panel.

And what happens if a controller fails? Nuthin' I hope, except for no charge from the panels.

[Mike90250]

Adding controllers in parallel is fine. If they can be "interconnected" with a data cable, their charging can be synchronized, so both are charging at full speed ! Otherwise, one will ALWAYS sense a full charge, and slow down to the next stage, and you are left with one charger working instead of 2. It might be a 5 minute difference, or 2 hours, depending on how well the factory set the voltage sense in them.

These are likely PWM chargers, that switch the PV panel on or off (connected or disconnected) and they don't dissipate much heat.

Open circuit PV's are fine.

[pmaru77]

I don't think there is any good reason the interconnect these chargers witha data cable. Since the 2 panels add up to 100W and a single charger is good for up to 120W, It only makes sense to run the panels in parallel to a single controller. If I jump up to more panels, then I would look for a controller with a higher rating, and yes they are PWM chargers? Description below.

Solar Charge Controller
Suitable for 12 Volt Nominal Panels
Maximum Input Voltage: 24V
Maximum Input Current: 8 Amp
Handles 12 V Panels from 5 to 120 Watts
LED Light Display Indicators
Battery Over-Discharge Protection and Monitoring
Battery Over-Charge Protection and Monitoring
Solar Panel Back-Feed Protection
Intelligent Controller

Hardened White ABS UV Resistant Outer Skin
User Friendly and Easy to Install
Thermostatic Over-Heat Protection
Compact and Light Weight with Superior Durability
Mounting Clips and Screws Included
Pre-Wired for Ease of Installation
Surface or Flush Mount Ready
1 Year Full Warranty (Parts & Labor)

[Sunking]

Is ther anything wrong with having one controller per panel?

Yeah it gets real expensive real fast and waste a lot of energy. A PWM controller turns your 100 watt panel into 50 to 60 watts. If you use a 24 volt panel on a 12 volt battery you turn your 100 watt panel into 40 watts.

So I say go for it, you got nothing to loose.

[Bala]

I don't think there is any good reason the interconnect these chargers witha data cable

In a properly set up system it can make difference, controllers will not generally read exactly the same voltage.

Without the data cable/interface you can have a situation where one may change modes and the other then can not? this was happening in my system.

using my system as an example, 2 sets of panels and a controller for each, In the morning they are meant to reach 29.4V for for 3 minutes, then change to absorb. as the controllers read slightly different voltage one will be at 29.4 and the other at 29.3, the first one changes to absorb of 28V, then the second one only has half the panels so can not get the batterys up to 29.4V but may be able to reach 29V and will stay there all day.

With the controllers connected by a data cable/interface you end up with a master and slave type set up and or they talk to each other. So that when one controller registers the battery has reached a preset voltage and is going to change modes the other controller will change as well.

hope that makes sense?

[pmaru77]

Thanks for the help. Too bad battery cost is the killer for off grid solar systems. How about designing a alternate storage place like a large flywheel and then when night comes, you run off the kinetic energy of the flywheel. Similarly to the magnetic launching system that they use on the new aircraft carriers.

[Sunking]

How about designing a alternate storage place like a large flywheel and then when night comes, you run off the kinetic energy of the flywheel. Similarly to the magnetic launching system that they use on the new aircraft carriers.

Because they only give you a few seconds of power. Flywheel UPS have been around for a long time and are extremely inefficient. Air craft carries have more power than they know what to do with and efficiency is of no concern.

[pmaru77]

Because they only give you a few seconds of power. Flywheel UPS have been around for a long time and are extremely inefficient. Air craft carries have more power than they know what to do with and efficiency is of no concern.

You still following me around? When is a joke a joke or not a joke?
You give me a flywheel from a carrier spinning max, and I'll show you how to get electricity out if it for more than a few seconds.

[Sunking]

You still following me around? When is a joke a joke or not a joke?
You give me a flywheel from a carrier spinning max, and I'll show you how to get electricity out if it for more than a few seconds.

Why would I follow you around?

I can show you commercial Flywheel UPS. They are only intended to last long enough to get a generator on line.

Here is a friend of mine, Marlin demonstrating a 300 Kva Flywheel UPS at a Las Vegas convention I installed one of these in a Verizon Data Center two years ago. Watch the video and see what is real. Note 15 seconds and it is done. It was removed and replaced with a conventional Battery UPS.