New user

Photowhit

Re: New user

I personally am not very worried about a fire, but I'm sure your insurance agent and or mortgage holder would be, and will likely want your system inspected, the reason why I suggested it. Other wise they will likely want you to have a 'qualified' electrician sign off on it or with draw your insurance or call your mortgage, NOT something you want to go through! It may be that your Aims inverter is either not UL certified or UL certified for mobile use (458 rather than 1741 home use). It may be that you could have this okayed as a backup energy source and have less stringent levels...

It's not my end of the world. I own my place and am un or self insured, I may want to have insurance in the near future as I sold my other place and it would be a hardship if I had problems here. We have had a forum member near St Louis loose some panels to severe hail, so you might want your panels ensured for that reason as well (mine have been trough near 1" hail with out an issue, but they are also set at a winter(greater) angle.

Do you know that all around the areas that you live Ameren has a great rebate program going! paying $1.5 per installed watt of solar this year, almost makes you want to move out of town doesn't it!

Cariboocoot

Re: New user

getravi wrote: »

From what I read on an earlier post (July 15th by ILFE), the purpose of the breaker is to protect the wiring. As long as the wiring meets/exceeds the Isc of the Panels (and it does), the only need for a breaker/fuse is to serve as a disconnect. This is the purpose I intended -- for servicibility of a string. Thus, each string (8.9A) uses a 10 AWG wire and goes thru an AC breaker which I am using as a switch. 4 such strings (hence 4 breakers) combine in the panel (panel A for example), where the currents are summed up before going to the morningstar controller. Perhaps its hard to read on the drawing, but it does indicate "Each PV string to separate breaker"

When a PV or PV string shorts it becomes wiring. It has a maximum current rating (usually 15 Amps). It is connected to other PV in parallel. They have a maximum output current rating. When the output current of the combined PV exceeded the maximum of the shorted one the circuit experiences over-current and things start on fire.

Let's put some numbers to it for an example:

Three panels in parallel.
Isc of each panel 9 Amps.
Maximum series fuse rating on each panel 15 Amps.
One panel shorts; becomes a conductor capable of 15 Amps maximum.
Other two panels output 9 Amps + 9 Amps or 18 Amps total to that conductor.
Conductor (shorted panel) starts fire on roof, house burns down, much weeping for loss.

Don't even think about doing another system for someone else if you can't grasp this concept; you will be liable for that system and if something goes wrong ...

Photowhit

Re: New user

The breakers are there to prevent back feeding a single string of panels from the rest of the panels in an array in case of a short in one string. Hence the need for DC rated panels and also the reason that if you have just 2 strings of panels you would not exceed the panels rated only being able to back feed the amps of a single string. They are more than a switch.

This is also why using the polarize breakers, the positive side of the breaker goes to the charge controller, since it is the back feeding that presents the problem.

getravi

Re: New user

I follow you. I will try to find some inexpensive DC fuses/breakers (perhaps DIN rail type) that I can swap out my makeshift panel/combiner box and breaker combination. I got the idea of the make shift combiner boxes from the internet. Did anyone else find a link to this video that how to use a regular AC panel as a combiner box?

Do you know of any inexpensive DC breakers that fit into siemens/murray AC load centers

Cariboocoot

Re: New user

getravi wrote: »

I follow you. I will try to find some inexpensive DC fuses/breakers (perhaps DIN rail type) that I can swap out my makeshift panel/combiner box and breaker combination. I got the idea of the make shift combiner boxes from the internet. Did anyone else find a link to this video that how to use a regular AC panel as a combiner box?

Do you know of any inexpensive DC breakers that fit into siemens/murray AC load centers

The box they are in isn't the problem (although a standard box used outdoors would be).
Breakers need to be able to safely interrupt the maximum Voltage expected (Voc) for the type of current above the rated limit. This doesn't mean the AC breakers won't work (or even that the DC ones will for that matter) just that they might not. And when you're talking about protecting from fire hazard "might not" isn't good enough.

If the investigators pick through the ash and rubble and find non DC rated breakers on DC lines ... CLAIM DENIED. Then lawsuits start.

MidNite has DC breakers that fit DIN rails. Sometimes it's easier to gut the box you have and change everything, if the box is suitable. Square D make QO breakers with a DC rating (<48 Volts though). On the whole, the larger the system the more worthwhile it is to spend the big money for the right equipment and not try to fabricate something yourself (at least not something of this nature).

BTW for the larger system you're contemplating you can save yourself a lot of grief by going with SMA Sunny Island (or two) and have the rest of the array power AC coupled to it via Sunny Boy GTI's. No extra controllers, no risk of blowing batteries apart with too much current, all components designed to work together.

Photowhit

Re: New user

I'll personal message(PM) you a link to the breakers I found, I suspect gutting a box and adding a Din rail, might be as expensive as buying a baby box or a Big Baby Box (a little more room for your buss bar) Though you might be able to find these cheaper since your in the field.

getravi

Re: New user

How do u feel if I were to simply put a standard automotive glass fuse (15A, 125 volts) inline prior to my AC breaker. This way, the AC breaker can still act as a simple disconnect as intended, the fuse would still act as a DC protection device for each string. I already have several inline fuses and fuse holders from another project I had going when I was building my battery bank monitor. I built 16 inexpensive (less than $5 each total) volt meters for my 16 batteries that show me battery voltage at all times. Each display unit has a fuse inline to protect the display element. I still have several fuses and fuse holders left over. It seems like this would be a simple and cost effective solution.

Cariboocoot

Re: New user

It would be if automotive fuses were 125 Volt. They're not. Try 32 Volt. So the question then becomes: is the PV string Voc <32 Volts? Probably not.

If you've got 15 Amp 125 Volt glass fuses they are AC line fuses. But here's the good news; they will probably work because fuses don't have issues with current direction (unlike some circuit breakers).

See what a pain it can be trying to adapt things to different uses?

By the way, if you have sixteen batteries measured by sixteen different Voltmeters those batteries would have to be not connected to one another in order for the meters to read properly.

getravi

Re: New user

I wish I had never seen that post on the internet about making a combiner box out of an ac load center. They should have atleast mentioned where to get DC breakers with high enough voltages.

I am looking at Outback Radian series for the next install and sticking to mostly outback stuff (inverter and controller). I like the fact that the Radian seems to have an automatic transfer function built in.

Photowhit

Re: New user

Cariboocoot wrote: »

By the way, if you have sixteen batteries measured by sixteen different Voltmeters those batteries would have to be not connected to one another in order for the meters to read properly.

This includes at night when you disconnect the inverter, if they are in parallel strings, they will try to raise the voltage of low cells, as I mentioned earlier.

The AU(?) midget size fuses do come rated for DC and up to 600+ volts. These are 10mm x 38mm, this size is often used in car audio systems, but rarely in the cars electrical system. This is the size I used in my combiner box;
Attachment not found.

Cariboocoot

Re: New user

That's a very nice home-brew combiner box, Photowhit!

getravi

Re: New user

yes, but because I have a breaker for each battery bank, when I wish to make accurate assessments, I can turn off all breakers but 1 and look at 4 voltages at a time. Then, move to the next string. The idea was to quickly identify a failing battery. Will this not work?

Cariboocoot

Re: New user

getravi wrote: »

yes, but because I have a breaker for each battery bank, when I wish to make accurate assessments, I can turn off all breakers but 1 and look at 4 voltages at a time. Then, move to the next string. The idea was to quickly identify a failing battery. Will this not work?

You couldn't have used a DMM for that?
Disconnect each in turn, check its Voltage with multimeter, reconnect, move on to the next one.
That is if there's any reason to suspect a failure; one of the problems of multiple parallel batteries is that there's no indication one has gone bad until it is so bad it is having a serious affect on the others. By that time it's usually too late.

Photowhit

Re: New user

Yes, you've got it, but you will want to leave the batteries dis connected for a while, as a bank it will level the strings, but once disconnected it will take a while for the cells voltage to settle. This is another reason for checking a cells 'true' charge with a hydrometer. Since you leave the batteries dis connected over night though you should get a pretty good idea by morning, just disconnect all the strings and check voltage in the morning.

...and thanks 'Coot!

getravi

Re: New user

using a DMM is a bit difficult as the batteries are on multiple shelves and in a separate room. The breakers are easier to get to and the display panels for the batteries are right by the breakers and are layed out just like the battery banks.

You've got me concerned about my AC breakers however. So, would it be safe to put glass type automotive fuses inline prior to my AC breaker. I don't think the voltage would matter much.

zoneblue

Re: New user

What sort of breakers for the battery strings? Theyll want to be good ones, like midnites 250A carlings or similar. AC breakers there are even more of a no no.

While the economics of this project are debatable, i would probably have done it with a pair of midnite classics, and a smallish set of AGMs which can happily take as many amps as you can throw at them.

As fully half your demand is aircon id definately be looking at shading and related glazing issues.

getravi wrote: »

yes, but because I have a breaker for each battery bank, when I wish to make accurate assessments, I can turn off all breakers but 1 and look at 4 voltages at a time. Then, move to the next string. The idea was to quickly identify a failing battery. Will this not work?

getravi

Re: New user

no. Each breaker for the battery string is from Midnite as are the breaker for each morningstar controller. Each battery string has a 100A DC breaker since I dont want any single string to draw/put in more than 100 amps.

Similarly, each morningstar controller has a 80 amp DC breaker as it goes to the battery bus bar. The breakers allow me easy serviceability to various areas of the system. I have also rigged up some reed switches to each breaker that alert me if any breaker gets tripped.

I designed the system allowing for upto 2 battery string failures to occur and still keep on working.

Cariboocoot

Re: New user

getravi wrote: »

You've got me concerned about my AC breakers however. So, would it be safe to put glass type automotive fuses inline prior to my AC breaker. I don't think the voltage would matter much.

Why AC breakers are apt to fail when used for DC: AC crosses zero Volts with every cycle, effectively shutting itself off. This makes it much easier to interrupt than DC, which will try to sustain an arc at any Voltage above 15. Thus the gap created by an AC breaker doesn't have to be as wide and the contacts don't have to be as resistant to arcing. Place fuses in-line solves this issue for fail-safe, but not for disconnect. If you want to be sure of safe disconnection of the panels, cover them first to drop their output.

The fuse Voltage rating does matter; it has to be above the Voc so that if it is called upon to interrupt current the power doesn't just arc across it and cause more problems (sustained arc plus short circuit).

getravi

Re: New user

ok. I will try to replace the breakers I have in my home made combiner boxes with DC rated breakers. Once done, all the breakers in my system will be DC rated and appropriately sized. Right?

Also, does anyone have any negative comments about Midnite solar's classic 150 MPPT controllers. To me, they appear to be quite fine and could be a nice fit with an outback radian series inverter for a future endeaver.

Vic

Re: New user

getravi wrote: »

...

I am looking at Outback Radian series for the next install and sticking to mostly outback stuff (inverter and controller). I like the fact that the Radian seems to have an automatic transfer function built in.

Hi getrivi,

Just to be clear; All of the high quality, larger inverter/chargers have built-in Transfer switches. And, these transfer very quickly, and usually without even a slight flicker. Just FWIW.

And to the later question, MidNite Solar is the real deal. The Classic CCs are very capable, and undergo continuous improvement via Firmware updates. These large CCs are generally a good fit in larger systems, IMO. MidNite solar has best-in-industry customer support/service/tech support, often from Principals in the company.

One added point, regarding battery banks, especially with racked batteries. Vertical stacking CAN increase the temperature differences between the batteries. In systems with many batteries on racks, these temperature differences increase.
YES, it is fairly common to see very large UPS battery banks, racked. These are often in conditioned spaces/rooms, and are infrequently cycled -- both of these factors reduce the temperature differential between the batteries.

With large temp differentials, it becomes very difficult to know just where to place the battery temperature sensor/s.

FWIW, opinions, YMMV. Vic

Cariboocoot

Re: New user

Vic wrote: »

And to the later question, MidNite Solar is the real deal. The Classic CCs are very capable, and undergo continuous improvement via Firmware updates. These large CCs are generally a good fit in larger systems, IMO. MidNite solar has best-in-industry customer support/service/tech support, often from Principals in the company.

FWIW, opinions, YMMV. Vic

Aw, Vic; you mustn't express opinions like that 'cause people get upset.
Oh wait; you're not a moderator so no they won't. Never mind. Just stick to telling it like it is.

drraptor

Re: New user

@getravi do you have hard data on how much you produce per day and how much you consume ? have you connected your morningstar CC to your pc ?

Vic

Re: New user

Cariboocoot wrote: »

Aw, Vic; you mustn't express opinions like that 'cause people get upset.
Oh wait; you're not a moderator so no they won't. Never mind ....

Marc, this great site runs very, very smoothly. This would not be the case without ALL of the work that you and BB Bill do, every single day.
Have said before, that things run so well here, that we members simply do not know much of what must be going on.

This is not to mention all of the succinct information and data that you Moderators , and often, other members contribute.

For you Mods, this represents much more than a full-time job! And, all for no pay, other than some satisfaction, and some static and carping from we members.

Thank You, Cariboocoot and BB Bill for everything that you do, and to Northern Arizona Wind & Sun for paying the bills to allow this terrific site to be such a great resource.

By the way, Marc, there are a couple of nits with you, I have to pick ... kidding ... Thanks! FWIW, Opinions, shared by many, we think!
Vic

DanS26

Re: New user

This is a great thread.

The OP has presented a DIY system that has challenged conventional thinking about how to build a cost effective off grid system. That is a good thing. Yes, it is only 1.5 years old and could implode anytime...but then again it could last 10 years.

I think most DIY'ers underestimate (myself included) the value of their own labor and do not include it in the cost and payback of their projects. Non-DIY'ers hearing these great returns and benefits get the wrong impression and are sorely disappointed when they try to replicate the project which includes having to pay someone else to complete the project.

As a general rule, I tell people that if you have to pay people to do what you want to do it will cost twice as much.

getravi

Re: New user

yes, I use MSView with the morningstar regurlarly. I also use the web interface with the tristar daily to see each controller. I also have the morningstar meterhub that sums up the data. I also have a Kwh meter coming out of the inverter that tells me what I have used. I also use my DC clamp on ammeter regularly to gage how much current is being drawn from each battery string and how much is being delivered by the charge controllers to the inverter. Ofcourse, there was the initial math and measurements made for each circuit before I designed the system - and finally compared everything to my utility bills. All is in line. I use and consume about 40KWh over a 12 hour period summer/winter.

drraptor

Re: New user

getravi wrote: »

yes, I use MSView with the morningstar regurlarly. I also use the web interface with the tristar daily to see each controller. I also have the morningstar meterhub that sums up the data. I also have a Kwh meter coming out of the inverter that tells me what I have used. I also use my DC clamp on ammeter regularly to gage how much current is being drawn from each battery string and how much is being delivered by the charge controllers to the inverter. Ofcourse, there was the initial math and measurements made for each circuit before I designed the system - and finally compared everything to my utility bills. All is in line. I use and consume about 40KWh over a 12 hour period summer/winter.

Can't you post the data for a typical day :-)

Photowhit

Re: New user

DanS26 wrote: »

The OP has presented a DIY system that has challenged conventional thinking about how to build a cost effective off grid system.

This is NOT an off grid system, while he uses it off grid, he could not use only this system off grid, he must have the grid for over night use!

DanS26 wrote: »

That is a good thing. Yes, it is only 1.5 years old and could implode anytime...but then again it could last 10 years.

It obviously has worked out reasonably well for 'getravi' that is why I've only suggested safety fixes and different monitoring, I question how well the batteries will hold up and really want it to work for a while. I have an off grid system with a minimal battery and think in some places, like Missouri trying to run an A/C in the summer, it may be the best bang for the buck, with only minimal draw backs.

getravi

Re: New user

I agree with you whole heartedly. Having done this project entirely by myself and with the help of my family with the installation on the roof (about 2 months worth - weekends only), I saved a fortune. State farm estimated the cost at $75000 for a 10kw system and that is what they tacked on to the replacement cost to my home owners insurance policy. This stuff is not hard to do, especially now that I have found great forums like this one. I only wished I had known about this place earlier. For about the just a few thousand more, I could have purchased an outback Radian inverter and Midnite classic 150's. But I am not complaining. I've learned quite a bit here but most of all, that the overall concept and design I implemented was along the right path.

getravi

Re: New user

I will try to take a snapshot of the tristar meter tonight and post it tomorrow.

Cariboocoot

Re: New user

getravi wrote: »

State farm estimated the cost at $75000 for a 10kw system and that is what they tacked on to the replacement cost to my home owners insurance policy.

I bet most installers would love to be making that kind of money: $7.50 per Watt installed!