DC Breaker Opinion

Re: DC Breaker Opinion

I don't know what you mean by "mounting feet" (Edit I went and looked and now see what you mean about mounting feet)

The square D QO is the only "generic" breaker that I know of that is DC rated. (Under 48 vdc) The nice thing about these breakers is that they are readily available nearly every where, including the big box stores. As a result, QO breakers and load centres are pretty reasonably priced.

Tony

Re: DC Breaker Opinion

Yes the Square D QOU is a DIN Breaker. I've used them as a part of a brand X ACCB L conduit box.

Have noticed that Midnite appears to offer some DIN AC breakers (in addition to the DC breakers which have been avail for years), which may work in their Baby Box, and the next size up-- the Big Baby Box.

Am just now specing an order to Northern Arizona WInd & Sun -- the host of this fine site, so will know more in a day.

I have NOT found the QOU in general distribution (ie at Home improvement centers). But they seem common in the RE side of things.

It appears that there are even 3-Phase DIN rail breakers again from Northern AZ W&S. Cool. Will advise on what I find. Vic

Re: DC Breaker Opinion

Midnite Solar will have about any combination of breaker you need ac or dc. They also offer a very wide range of boxes and transfer switch boxes to work with there breakers.

Re: DC Breaker Opinion

If I am seeing this correctly, a 6 slot Square D load centre would do what you need.

1 20 amp QO breaker on the PV
1 20 amp QO on the Iota
1 40 on the inverter lead

In this incarnation, I might use a 40 amp FUSE at the battery bank, that would prtect the wire from the battery to the load center. This would then feed one buss side of the breakers. One 40 amp breaker could then feed the other buss and the other 3 breakers if I am explaining this properly.

That way the all the battery current (in both directions) flows through the fuse at the battery, and then through the breaker (acting as a system disconnect) The other breakers would either be fed from that "main" 40 amp" in the case of the inverter, or be fed from the others in the case of the Pv or Iota. Since they all combine at the battery anyway having them combine in the load centre seems cleaner.


I think that Square D load centres come in many different configurations so a 6 space box should be pretty easy to find. http://www.squared.com/us/products/load_centers.nsf/unid/250EBE3967B7E08085256A6300646675/$file/4_8Frameset.htm

About $20 at Home depot or Lowes or Canadian tire.

Your system is nearly identical to mine, except I run a number of DC loads (12vdc) as well through a Square D box. The only difference is that I feed the battery charger on it's own leads, with it's own in line fuse. I don't know why I didn't run it through the load centre but I'm sure I had a reason.

With no offense to Robin and BoB I don't know what you need the Midnight combiner box for. The Square D is probably much cheaper and more easily sourced locally.

I hope this is clearer than mud.

Tony

Re: DC Breaker Opinion

The load center will not work the breakers are all tied to a common bus therefore you could not bring pv in and battery out.

My recommendation would be to us a Midnite Big Baby box it has more room the list price is 45.00

Or if you want more room you can use a Midnite MNPV6 just don't use the bus bar.

Or if you want to get real fancy you can use a Midnite Mini DC box.

Re: DC Breaker Opinion

Crystal,

Mikeo has it exactly right. That said, either buss or both for that matter, can carry current in or out. In other words it doesn't matter if you connect "to the battery" at the battery or at the buss as it is the same net effect. What is important is that the breakers protect the wires they are designed to protect. (This is why I suggest an inline fuse at the battery, serving to protect that wire from the battery to the breaker. A breaker doesn't care which direction the current flows).

As for the 12 vdc loads. Our system started out as a pure 12 volt system, not unlike a RV system. Slowly we have evolved away from 12 vdc in favour or 120vac as inverters have gotten better and cheaper. There is a ton of 12vdc stuff both for the truck as well as the RV market. The original intention was to use the inverter sparingly, but since they are so efficient nearly everything new now runs on 120 vac.

We have a dual wiring system that provides 12 vdc lighting in a number of areas mostly for emergency lighting. We also carry 12vdc to the fridge to power the control board (LP fridge) The water pump is 12 vdc (we actually use a voltage doubler to run the pump on 24 vdc). We have a 12 vdc paddle fan, we use a car type radio with Ipod adaptor wired for 12vdc for a stereo. We also us 12vdc for the sat/cell phone. I also have a number of small computer fans moving air around the house as the season requires. (Cheap to buy, quiet to run). I find 24vdc fans at the computer recyclers and run them on 12. They run very quietly then, and still move a bunch of air.



I hope that helps.