Let the show begin....

Rngr275 · July 2012

Readers Digest Version:
Bought an Amish house, no grid, mega$$ to get the grid in, going off grid, measued and re-measure what I think/thought we could get by with for KwHr per day. Came up with 3KwH/dayr, padded that number up to 5KwHr/day, will probably still be off but I had to start somewhere. Met with 3 installers all well known and have been in the business for awhile. Chose 1 who 1) lives off grid, and 2) has been doing off grid systems for 10+ years. Here is the system being installed or at least listed in the contract (FYI Upstate NY, 4.3hrs of sun average, 2'ish in the winter):

The inverter/ battery system consists of:
1) 1- Outback VFX 3648 inverter
2) 1- Midnite 175 STS-L E-panel with circuit breakers for the inverter, charge controller and TM2020
3) 1- Outback Mate inverter programming module
4) 1- Set of 4/0 x 10' UL listed inverter battery cables
5) 1- Trimetric 2020 battery monitor
6) 16- Trojan L16-RE series 370 amp hour, 6 volt deep cycle batteries (740 amp hours @ 48VDC / 35,520 kWhrs AC)
7) 16- 2/0 x 12" battery interconnect cables
8) 1- 300 volt AC SPD surge arrestor
The PV system consists of:
1) 16- 240 watt PV modules (established name brand, to be determined by availability)
2) 2- DP&W 8-module, adjustable tilt pole top mounts (4-6 week lead time from factory)
3) 2- 6" x 21' schedule 80 pipes for array mounts (non-galvanized)
4) 1- Classic 200 charge controller
5) 1- Midnite MNPV12-250 combiner box (for 6 sub arrays)
6) 4- Midnite MNEPV15-300 combiner breakers, 300 volt rated
7) 1- 300 volt DC SPD surge arrestor

I really need to decide on a generator:
I have a Hond2000i, I am joining an LP co-oprative so I can get LP cheap(relative) and am seriusly considering the Ecogen or get a portable gas for the year (cheaper) and see how it goes. The ecogen puts out ~50 amps, the Honda~13 the gas one puts out about the same as the Ecogen. Any suggestions?

Thanks all!

niel · July 2012

Re: Let the show begin....

looks pretty good to me. i would probably opt for the battery interconnects to be of the same gauge or better than the largest gauge used elsewhere so i'd interconnect with 4/0 wire. the installer is thinking the strings are being shared so he's cutting back on the wire, but low losses here are vital to help keep balance in the battery bank. also if one string were to be removed for any reason the other string would be handicapped with the smaller gauge wire.

you should inquire about how the ground is intended to be done. you will need a ground rod outside at the main ac breaker box as the primary ground rod and it would be good to ground the other pvs with 1 rod per pole. now the connecting of the grounds would depend on if done by nec standards or the standard i prefer of interconnecting the ground rods underground without a ground wire entering the home with the pvs wires. your installer will probably insist on the nec standard and most likely won't understand the danger that presents in bringing lightning into a home.

sorry that i won't be of much help in your genny decision making.

vtmaps · July 2012

Re: Let the show begin....

You've made a lot of progress since your previous threads. I do still have some comments:

Rngr275 wrote: »

Trimetric 2020 battery monitor

I have a trimetric. I like it. If you use an outback FNDC monitor and an outback FM80 controller you could control your charging via the 'end amps' function. Some day Midnite will have their own monitor system to allow end amps programming.

Rngr275 wrote: »

16- Trojan L16-RE series 370 amp hour, 6 volt deep cycle batteries (740 amp hours @ 48VDC / 35,520 kWhrs AC)

Two strings is OK, but one string of larger cells is better. Other than the electrical connections and current sharing, there is another reason to go with one string: only 24, rather than 48, pools of sulfuric acid to measure and maintain. If you go for 2 volt cells, avoid trojan... their 2 volt cells are actually 3 cells in parallel with 3 pools of sulfuric acid per 2 volt battery.

Rngr275 wrote: »

2- DP&W 8-module, adjustable tilt pole top mounts (4-6 week lead time from factory)
2- 6" x 21' schedule 80 pipes for array mounts (non-galvanized)

Two 21 ft pipes?!?! seems like too much pipe. If they're in concrete you shouldn't need more than 5 ft below grade. Also, check those pole top mounts. I don't think they allow you to tilt all the way vertical. In snow country its worth the effort to find a mount that allow full vertical.

Rngr275 wrote: »

1- Classic 200 charge controller
16- 240 watt PV modules
1- Midnite MNPV12-250 combiner box (for 6 sub arrays)

I can't imagine how you are going to divide 16 panels into 6 sub arrays. you will void the warranty if you cut those panels into pieces.

On the subject of array configuration, consider the Midnite Classic 150. It handles higher current. You don't want either Classic (150 or 200) to have an input Vmp over 90 volts (for a 48 volt system). Sure they can handle more, but they run more efficiently and cooler when the input is not so much higher than the output voltage.

--vtMaps

Photowhit · July 2012

Re: Let the show begin....

I'm not sure your not pushing the limits of the Classic 200, it max's at 79Amps and your array, by numbers, is 80 Amps at 48 Volts. The classic Max (for the 150, which I know about) is at 2x the running voltage, so higher voltage might also mean lower possible through amps, this is a rare thing, and you won't loose much... Midnite has a calculator Here. I think they let you go to 1.2x the rating...

I was actually thinking running a 3600 watt inverter on 48 volt, you likely could go with smaller interconnects, but it's fine to be over sized, won't hurt anything.

I saw you ordered 4 breakers, so I'm sure 4 strings?

niel · July 2012

Re: Let the show begin....

photowhit,
i don't think it to be a good idea to run the classic 150 as the voc total for many 240w pvs will be close to 150v. add to that the fact that he is in a northern state that gets cold and it would periodically go into hypervoc so i do agree with his choice of the cl 200 with 4 strings of 4 in series. as to being near the max on current he usually won't see the max occur (like edge of cloud) and should it occur it will just hold at the max until it goes back down again.

i do agree that he won't be optimally efficient going high voltage, but his alternative might be to go with 5 strings of 3 pvs in series and this won't work out for 16 pvs and he'd lose the power of one pv. the classic 150 would suffice for this arrangement. even going to 18 pvs would work as the vmp would be at 90v and the 150 is rated 83a (4847w) for 90v. now my simple math says with 18 pvs, 18 x 240w = 4320w and dividing this by 48v is 90a. this might be pushing things in both cases to the edge, but like i said, most times the pvs won't be delivering full output.

btw, i gauged this by specs from the sw240 from solarworld. kyocera has a slightly lower voc, but for a series arrangement of 3 or 4 pvs this won't reduce the voc by much to make much of a difference.

mtdoc · July 2012

Re: Let the show begin....

I would definitely consider getting the Flexnet DC battery monitor instead of the Trimeteric. It can be mounted in the Epanel. Even with the Midnite Classic CC instead of an outback CC, the FNDC is a very good battery monitor and integrates well with the Outback inverters. You would then be able to use an inexpensive software program such as WattPlot or GreenMonitor to monitor your AC loads, PV or generator amperage input to battery bank, battery state of charge, temperature, etc. The free Local App for the Classic CC will allow monitoring of PV production and some battery parameters as well. I do this and find the 2 very complimentary.

If you don't need automatic generator starting, your Honda eu2000i can be a fuel efficient solution for when your PV cannot keep up. It can be easily converted to run on LP if desired. It can be paralleled with a second eu2000i to give you 30 amps of 120 VAC.

Photowhit · July 2012

Re: Let the show begin....

Sorry Neil and MtDoc, I was only making refence to the 150 in that it allowed the most through Amps at @ 2x the in put votage, from my experience and that her was asking for max already and trying to do 4+ times the input voltage.

I made it to work, and we're slow so I looked it up, page 8 of the manual for midnite classic 200 running 140 volts input running a 48v system the max of 65 Amps out put, and he's above the max suggested array of 3796 watts (which I think includes the 20% buffer)

Might be important to squeez out those extra amps in the grey winter months.

Rngr275 · July 2012

Re: Let the show begin....

I have a few answers but will direct the installer here as he will have the answers since I am still trying to learn this new language.

VT: The Top mounts go "Near" verticle (~8-10degrees) I mentioned the ability to go verticle but he really liked these because they were easily changable buy one person.

I will be checking on the rest.

Thanks gents.

halfcrazy · July 2012

Re: Let the show begin....

I can say given the info DPW top of pole racks are the best period. They are good rugged mounts that just never fail.

The FNDC is truly a judgment call the Trimetric will give you lots of useful data and would be what I would have typically specked my self.

As for 21ft of pipe that is the length they come in and you could saw off some your self but I doubt your installer needs 2 pcs of pipe 4 ft long or so. With a 4 by 4 top of pole mount the pipe needs to be pretty tall. You need 6-7ft minimum to account for 2 panels, 4-6 ft minimum to account for snow and if it where mine with that big an array 7-8ft in the ground would not be out of the question.

Now I can put my official MidNite Solar hat on and say I agree the 200 is the way to go here as the number of panels (16) truly only divides by 4. You can not do 2 panels in series and sufficiently charge the 48 volt battery in the summer. The 200 may on very rare occasions hit the current limit this will not hurt anything.

Ryan

Let the show begin....

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