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getravi · July 2014

Re: New user

The city planning division said I can go ahead and do everything as long as I don't put power back into their grid. Also I will not be getting any money back from the city, but the most important part was that I do not put any power back into the grid. The person I corresponded with was rsullivan@farmington.mo.gov

ButchDeal · July 2014

Re: New user

getravi wrote: »

The city planning division said I can go ahead and do everything as long as I don't put power back into their grid. Also I will not be getting any money back from the city, but the most important part was that I do not put any power back into the grid. The person I corresponded with was rsullivan@farmington.mo.gov

Net metering is the law of the land(state) they have to support it from the law and net metering means that they have to give you credit for the power you put on the grid. It is state law. Now in Illinois there are exceptions for municipal power companies so they don't have to.

getravi · July 2014

Re: New user

glad to hear it. I will contact city of farmington missouri and see what they have to say. Thank you soooo much

BB. · July 2014

Re: New user

An Off Grid inverter + battery chargers + batteries + additional wiring/fuses + 2-4x larger solar array because of battery/conversion losses and lack of more than ~2 days of "useful storage".

I would not hold your breath regarding GT Solar... We have probably hit the maximum penitration of "customer friendly" billing plans (typically 1 year net metering--By/Sell power at retail rates to utility, and utility "stores/arbitrages" power for 1 year period in monthly increments).

We are starting to see strong utility push back to GT solar as being subsidized by other non-GT customers & utility profits. You can argue otherwise, but those arguments are starting to be lost even at the state PUC levels.

You will instead of $4 per month billing charge and $0.20 per kWH, you will see $40-$100 per month billing charge and $0.06 to $0.10 per kWH charges. More and more of that is starting to happen.

And then there is the life of the batteries (typically 3-7 years for many), and replacing all of the electronics every ~10+ years.

It all adds up.

-Bill

getravi · July 2014

Re: New user

So are u saying, grid tie is a bad idea too? Are you saying, solar is a bad idea too in the long run?

Cariboocoot · July 2014

Re: New user

getravi wrote: »

So are u saying, grid tie is a bad idea too? Are you saying, solar is a bad idea too in the long run?

Nope.
There are those who think solar is bad. Strangely they all seem to be connected to electric utilities who stand to lose profit under existing rate structures when people make their own power and sell surplus back to the grid.

Ultimately there needs to be a major overhaul of the entire grid so that solar can be integrated. It can't replace other sources entirely due to the present storage limitations but it certainly can be used to ease the load during those hours when the sun shines (much as you are doing, in fact).

The only legitimate complaint utilities have (in my opinion) is that unlike other sources they do not have control over the home solar generation. As such they can't manage it as an integral part of the grid; knowing there are 'X' Watts available by flicking a switch. So home installs go from being varying loads ranging from 48kW to 0 kW to varying loads ranging from 48kW to -10kW. The existing management system has no model to handle this. Believe me; I know the man responsible for those models.

Photowhit · July 2014

Re: New user

Well I see that someone has stated that grid tie "net metering" is law of the land in Missouri. I live here and understand that they can make things very difficult. This law has changed since you built your system. I think early last year.

Your numbers are pretty good. You are benefitting from having a very minimal battery bank. Please understand what people here are saying about the charging of the battery bank. Since you have such a large load, the charge controller have no clue as to what state your battery bank is in. There are systems available now that measure the actual current going into you battery bank. A full Outback system might be your best bet, charge controllers and inverter/metering. You likely will not notice the batteries weakening until a starting surge shuts down the inverter.

Since it's been up and running, I suggest living with it and banking money for the day the batteries and/or inverter fail. If you wanted to tinker with it, perhaps replacing the charge controllers, though I don't know what else you need in the OutBack system to limit the charging current or even if it can be done with multiple charge controllers.

FWIW- I have a minimal battery as well, it's about the same capacity as yours(though a 24v configuration) and a 4Kw array and I'm 'over paneled' for my battery bank!!!

When looking for your next battery bank, you might check out forklift/traction batteries, they may cost slightly more by capacity, but have the potential to last considerably longer.

mike95490 · July 2014

Re: New user

The Schnider/Xantrex/Conext XW hybrid inverters can grid tie, or only do load shaving. (for when your AIMS inverter goes out). And they are fine with the Morningstar MPPT chargers keeping the battery bank full.

getravi · July 2014

Re: New user

Seeing that I have no choice with regard to net-metering and sending power back onto the grid, I looked at the Outback GRID-Zero inverters as was mentioned on an earlier post. The cost of implementing that solution seems to be much higher than what I have, but yields the same result. Isn't what I have implemented the same thing as a GT system that would be setup for SELL turned off, with battery backup (exception here is that the entire system is backedup up, not just a few circuits) and that I am using an off grid inverter at the same or less cost as other comparable systems?

Photowhit · July 2014

Re: New user

Unfortunately, The Aims inverter is a 'Cheap' inverter, rather than an inexpensive one. If it has worked for 18 months I would continue using it! Since you have the grid to 'back you up' just live with what you have. The advantage/need is to properly charge your batteries from what I see, that is the biggest failing of the system right now. You have the potential of presenting 8000watts/48v=166 Amps into your 460 Amp battery bank! That will damage/shorten the life of your batteries. Likely they 'like' a 1/8th charge rate max or 58 amps

getravi · July 2014

Re: New user

Thank you very much. I did not know that. I was under the impression that 4 morningstar controllers networked together via their meter bus network limited the charge current to only 60 amps for the battery. Is there anything I can add between my mppt controllers and battery bank to limit the rate of charge to the max of 58 amps. An alternative would be to add more batteries, but I hear that is not a good choice either since that means more parallel strings. I am learning quite a bit here on this forum. Morningstar was not able to help me when I started this 2 years ago.

Photowhit · July 2014

Re: New user

I don't believe so, though I'm not familiar with their meter bus network, but unless it measures the current passing to the batteries at a shunt placed just before the battery, it can only see the batteries and load together and not what current is passing into the battery.

getravi · July 2014

Re: New user

I looked at the Schnider/Xantrex/Conext XW hybrid inverter and it appears to be exactly what I needed all along. This inveter/charger runs its own subpanel, just as I have done on my system, runs off a battery bank, just as I have done with my system, uses grid power to charge the battery bank (not what I have done, but will do so shortly). I like the fact that the charge current for the various parallel MPPT controllers are regulated by the inverter. I also like the fact that it can be grid tied and and setup for sell feature enabled if so desired (i beleive)

westbranch · July 2014

Re: New user

getravi, pleased do yourself a favour and read up on the MidNite Classic controllers as well as the WhizBang jr and its ability to allow the controller to 'know' the amount of charge going into the battery, in addition to the total charge going out of the controller.

http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=21&productCatName=Charge%20Controllers%20-%20Classics

http://www.midnitesolar.com/productPhoto.php?product_ID=519&productCatName=Charge%20Controllers%20-%20Classics&productCat_ID=21&sortOrder=9&act=p

enjoy.

getravi · July 2014

Re: New user

That is the reason I have 4 parallel battery banks and 4 charge controllers. Each charge controller would put out a max of 60 amps. Event though all 4 charge controllers could possibly sum up to 240 at the same instant at the bus bar where they meet, the 4 strings would divide the current to 60 amps per string (asuming no cells have gone bad). I've made a very cheap volt meter (less than $5 each) for each battery that shows me the battery voltage at all times. I always know if a cell/battery is going bad.

Photowhit · July 2014

Re: New user

What your saying is not really possible, unless your running 4 different inverters, hence 4 different systems. What you have is 1 battery bank, made up of 4 strings, since at some point all the strings are connected. Since all the batteries are connected you also have 4 charge controllers feeding 1 battery bank.

Photowhit · July 2014

Re: New user

Since the strings are all connected, they should show the same voltage. If you have a single cell having problems it will bring that string down, but it will also bring the other strings down as they try to increase the voltage on the one string.

getravi · July 2014

Re: New user

I follow you. Do these other systems like Midnite solar inverters and the schneider xw hybrid systems support MPPT controllers that are not their own brand. This way, somewhere down the line, when my inverter and battery banks fail, I can update them to what you guys are suggesting here.

Photowhit · July 2014

Re: New user

Midnite does not yet make inverters. They Brothers boB and Robin once worked at Trace/Xantrex(now Schnieder) and started(?) Outback. They are currently the cutting edge of Charge Controllers. They have hinted that they would produce an inverter in the future and have asked about features on their website. Their charge controllers have the ability to measure the energy going into the battery across a shunt.

I think Xantrex's new system has the same ability, though I'm not familiar with it.

Outback's system I think is somewhat different, I think it uses the flexnet' system to interpolate the charge going into the batteries? I suspect a moderator that has been monitoring the situation will come along and correct me.

getravi · July 2014

Re: New user

I appreciate the input from all the users. Looks like my next design should be an Outback inverter with Outback/Midnite/xantrex charge controllers along with 2/6 volt high amperage battery banks for an off grid solution. I would still like to know if my initial design that I have implemented is sound as I have no practical experience in this stuff and I based this solely on reading product manuals and my own academic experience. Can you guys look over the drawing and tell me if it is sound so I dont make a mistake with my next system -- the 30KW system for my brother inlaw. I think it is, with the exception of the inverter brand, battery strings and size and a better charge controller - but I dont think the design is too off.

Photowhit · July 2014

Re: New user

I don't know about your fuse/breaker situation, does each string of panels have it's own fuse/breaker on charge controllers with more than 3 strings?
and is there a breaker between the batteries and the inverter? ...and are these DC rated fuse or breakers?

Is your system grounded?

Is/Does your town require an electrical system to pass inspection? if not does your insurance company and mortgage holder know about your system?

westbranch · July 2014

Re: New user

My belief is that you still need a usage assessment so as to tell us just where all that power is going...

It is far more than most of use are accustomed to thinking about.

Lots of inquiring minds here. From there we can suggest plan(s) of attack to go from the present to a future design, whatever it may be.

It may/will affect your next inverter choice ...

getravi · July 2014

Re: New user

Each string has a breaker that goes to the combiner box (it is an AC panel with AC breakers acting as switches). There is a DC breaker between each MPPT controllers output to the battery bank. There is also a DC breaker between each battery string. There is also AC and DC breakers at the inverter between inverter and battery bank and inverter and AC load.

The system is grounded.

The town does not require any inspection or permit, this is why I am all alone in this and have been in the blind. Thanks for reminding me about the insurance company. I will contact them soon.

getravi · July 2014

Re: New user

Load Description Voltage(VAC) Power Consumption(W) Qty hrs/day Total WH/day AH/day at 48VDC

TV (20" LCD) 120 200 1 3 600.00 13.89
Computer (laptop) 120 50 1 10 500.00 11.57
Printer 120 100 1 1 100.00 2.31
Network router 120 50 1 10 500.00 11.57
Radio (Sound System) 120 30 1 10 300.00 6.94
Alarm clock 120 8 1 10 80.00 1.85
20 cuft frig/freezer 120 60 3 10 1800.00 41.67
Microwave 120 1100 1 1 1100.00 25.46
Coffee maker 120 500 1 0.5 250.00 5.79
Toaster 120 1200 1 0.5 600.00 13.89
Dish Washer 120 1500 1 2 3000.00 69.44
Washing Machine 120 500 1 2 1000.00 23.15
Vaccum cleaner 120 1200 1 1 1200.00 27.78
Furnace Blower 120 750 1 10 7500.00 173.61
Air Conditioner 220 5000 1 4 20000.00 462.96
Ceiling Fan 120 30 5 10 1500.00 34.72

Total WH/Day= 40030.00 Total AH/day = 926.62

Photowhit · July 2014

Re: New user

getravi wrote: »

Each string has a breaker that goes to the combiner box (it is an AC panel with AC breakers acting as switches).

Unfortunately DC is a different creature, truly your AC breakers are acting just as switches. Code would require changing this to DC breakers. Code is about to change and require polarized DC breakers as they become more available. If your interested in becoming code compliant and want the security of not back feeding and destroying your panels, you will need to switch these out. Midnite makes breakers rated to 150 volts that are currently polarized. We just had a discussion about CIS DC breakers which are rated at 125 volts being pretty cheap currently, I picked up a dozen off ebay new old stock for $55 delivered. Perhaps preparing to switch to the polarized breakers. There are also discussions about the proper installation of these breakers, which is counter intuitive to some.

There are other code issues that we can't check, wiring to and from the inverter must be in conduit, and access to wiring above 30 volts must have 'limited access' so roof mounted would constitute limited access, but ground mounted panels should have wiring mounted in conduit or be fenced.

Might get an electrical inspector to check out your system, they are likely to see things even if they aren't familiar with the solar aspects.

getravi · July 2014

Re: New user

From what I read on this forum about needing a breaker for each PV string, it simply acts as a switch anyway and serves no other purpose. That is what I am using it for as well. Just a switch for maintainance purpose.

As far as the wiring to/from the inverter, my inverter and battery bank are located right next to each other, separated by a partitioned wall. The battery bank is in a ventilated closed room and the inverter is just outside it. The cables between them go through a 3 inch hole in the wall which is insulated as well. Thru the same 3 inch hole, I have the wires for the charge controller entering the battery room where the battery bank bus bar exists. This is where the inverter and charge controller tie together.

Many of you wanted to see my power usage and I detailed most of it -- so you can see why I average 40KWh+ over a 10 hr period. Similarly, the other office install I am looking at averages 3 times what I am using over the same 10 hr period and so I am looking for design reviews. I have done rough estimate (used Ammeter and rough estimates based on types of equipments found) and compared them against measured values using KWh meters I placed at the main panel.

As far as the city inspector coming in to look at my system, that is a no go. This is a small town with about 10000 people and I already tried that.

Cariboocoot · July 2014

Re: New user

getravi wrote: »

From what I read on this forum about needing a breaker for each PV string, it simply acts as a switch anyway and serves no other purpose. That is what I am using it for as well. Just a switch for maintainance purpose.

Wrong.
When you have more than two parallel PV connections the per-string breakers protect against a possible shorted string being subjected to the combined current of the other strings which can start a fire.
A breaker between the combined array and the charge controller is the one that will never function as current protection and will only operate as a disconnect.

getravi · July 2014

Re: New user

I agree, what I was saying, is that I am using the breaker as a disconnect only. From what I read on this forum, there was no need to have a overcurrent protection for each string. That is why I did not go with DC breakers as I had a whole bunch of AC breakers lieng around and AC panels only cost me about $10 each. I am using the AC panels as a combiner box/disconnect box for my pv panels.

Cariboocoot · July 2014

Re: New user

getravi wrote: »

I agree, what I was saying, is that I am using the breaker as a disconnect only. From what I read on this forum, there was no need to have a overcurrent protection for each string. That is why I did not go with DC breakers as I had a whole bunch of AC breakers lieng around and AC panels only cost me about $10 each. I am using the AC panels as a combiner box/disconnect box for my pv panels.

I just rechecked your diagram. It appears that for Controllers A, B, and C you have four strings of panels in parallel on each controller. You need string breakers for each of those and they must be DC rated breakers. Using AC breakers there is not safe.

getravi · July 2014

Re: New user

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"

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