Newby's 2nd system in Hawaii

sodamo · September 2005

I'm at the beginning of this process, but already an important question has come up. First some background.
I intend to build a house on the island of Hawaii, about 20 miles north of Hilo. We will be completely off grid. The house itself is basically 4 boxes - garage with laundry/bath, a master bedroom suite, 2 smaller bedroom suites, livingroom/kitcken/dining. These will be connected via covered decks (lanais). I will build a separate tractor/utility shed about 60 feet behind the garage. This structure will have the solar panels and house batteries, generator, inverter etc. To me the layout of the 4 boxes calls for using a separate subpanel for each to minimize wiring runs. When I showed the plans to the electrician his first comment was that he was concerned about distance of the subpanels back to the main system. The longest run would be about 120 ft. He said I should ask "my solar guy" if this was even possible. I don't exactly have a solar guy yet. Have talked to the one I will probably use, but only to extent of trying to meet, nothing about system. The system he built for a neighbor is a 24 volt PV and used Outback inverter and diesel generator backup. I want him to check our stream for possible hydro, but that is not relevant to my question.
So, my question is - do I have a concern having my sub panels upto 120 ft from the inverter? My uneducated thought is potential loss can be minimized by wire size - yes/no? Any other concerns I should have at this point?
Thanks
David

sodamo · December 2005

Re: Newby's 2nd system in Hawaii

OK, so the planning continues in ernest, having found a reputable solar installer that is familiar with the neighborhood and people are happy with his work. The electrician is happy in that we will run 240 volt feeds from the main panel to the sub panels.
We are early in the design of the system. One item that came up in discussion 48 vs 72 volt system. I figure this will affect both panel and battery decisons, but basically can anyone detail some pros vs cons of this choice? Performance benefits? Will most likely be using Outback PS4 and 2 or 3 3K watt inverters, MX 60 controller, haven't decided on battery size/brand/type. At this point, no DC loads, AC only. This is for house in Hawaii, about 20 miles north of Hilo.
Thanks
David

System2 · December 2005

Re: Newby's 2nd system in Hawaii

From what I remember from reading the regulations, the largest allowed battery bank voltage is 48V. You can run higher voltages to the controller but no greater than 48V from the batteries. At least that is what we in the CONUS are limited to. When you think about it 48V at say 1000 Amps can really weld things together. Might want to get a copy of the NEC and local building regs to look at, maybe go to the library if you cant find it online.

Jerry O.

niel · December 2005

Re: Newby's 2nd system in Hawaii

david,
this sounds like a large system you're putting in and i don't think your utility shed is going to be large enough to support that many pvs or at least utility sheds i've seen wouldn't be. i'm not sure just how big of a system you're going for, but 3 inverters will have an appetite better than seymore's and you have to be ready to provide that much. the battery bank too will be huge, but i'll assume you and your solar guy have this figured out.
as to 72 vs 48v pv systems you can do either as both have good and bad points. higher voltage equals lower losses in the wires with slightly less efficiency in the controller to downconvert it to the lower battery voltage and that depends on how far down it's converted to. i'd say you do want to have a system that is slightly higher in voltage also because of losses due to lower pv voltage caused by heat. that means a system that would go from 48v pvs to 48v batteries wouldn't see it's required charging voltage as often than a system going from 72v pvs to a 48v battery bank. you won't be wanting a battery bank over 48v (regulations or not) as the inverters just aren't out there for those voltages unless you're going up into the non-battery backup systems that take voltages measured in the hundreds. this would be moot anyway for you as you aren't grid tied and antialiasing would mean it won't work in a non-grid circumstance.
as for the long wire runs it's good that you made that for 240vac. that does keep losses down, but you are correct in your thinking that you could just jump up a gage or 2 with your wires and keep those losses to a minimum too in comparrison to what you normally would've run those had they been much closer in distance. for that ac run as an example let's say i have a building 120ft away and am sending 20amps of 240vac to it. normally #12 is used for 20amp circuits, but in this case i'd use #10 because of the distance(extra wire resistance). that distance represents a voltage drop greater than you'd normally see in circuits of homes that don't have wire runs that long. i can't say for sure the nec wouldn't require something even better for that distance than what i stated in my example, but only used it as an example for your understanding.
i do recommend for specifics to read the nec requirements too.

sodamo · January 2006

Re: Newby's 2nd system in Hawaii

Thanks for the input guys
Sorry I wasn't more clear, but yes, the battery bank will be 48 volt.

Yes, I guess this will be a large system. Right now it's looking like about 4500 watts of panels. Any suggestions how to curb a pool pump's appetite? :?
As for the utility shed - well, that's what I call it, because it will be home to my utilities (and my tractor). Actually, it is a very overbuilt carport built over a 20 ft shipping container. The gable roof is 28'X30' with 3-12 pitch - basically 420sf on the southern exposure. Roof is 1" Galvamet panels supported by five 4"X10" beams over three 4"X10" beams that are supported by nine vertical galvanized pipes 4 1/2" X 15' with 5' sunk in 12"diameter holes filled with concrete. My wife and I finished the pipe installation & concrete work 12/26.

David

Brock · January 2006

Re: Newby's 2nd system in Hawaii

I have been looking in to more efficient pool pumps and have found the two speed units are about as good as you can get. Luckily my installer used one; it pulls about 300w in low and 1200w in high speed. It makes a huge difference in the long run. I have also heard it is better to run a pump slower for more time rather then faster for less time since the filter media can grab more dirt and doesn't make channels through the sand or other filter media.

sodamo · January 2006

Re: Newby's 2nd system in Hawaii

Thanks Brock

I'm learning it may not be "as simple as I hoped"

Seems things like gallons per minute, back pressure, the fact the pool holds over 39K gallons, weather, etc
Currently looking at a DC pump by Dankoff, on basis that we can run it during the day when sun is shining and it not be a major factor as far as batteries. Seems a number of web sites promote using a pump directly off PV panels, but is no solution for days when not enough sun to accomplish the task.

David

sodamo · February 2006

Re: Newby's 2nd system in Hawaii

Picked up my 36 KC125 panels yesterday and the Suncentric P pump and controller for the pool. Decided to install both a DC pump as primary and use the AC pump as backup. PV installation should start mid March provided my roof ships soon.

David

sodamo · March 2006

Re: Newby's 2nd system in Hawaii

This week I take delivery of my batteries. Rolls 4KS25PS. These are 4 volt, 1350 Ahr. I'll have 12 wired as a 48 volt system. Batteries are 15 3/4" X 10 5/8". 24 3/4" high and weigh 315 lbs. Configuration will be 2x6 (32"X66")

Anyone have a good battery box design? These will sit on a concrete pad (3' X 8") adjacent the end of my 20 ft shipping container and under the 28' X 30' roof that will support the PV's (36 - KC125s). So while basically outside, it will be mostly protected from sun and rain.

I have some thoughts I will put to paper, but roughly plywood sides, front and top. Sides will be slanted 30" in front to 42" rear. "Shed" type top hinged at rear with pvc vent. Front will have 4-6 screws for easy removal. The rear height is to allow room for a removable shelf sufficent to store a few gallons of distilled water and other maintainence items. Painted to match the container.

I'm debating 2 issues:
1. Floor - do I really need a continuous (plywood) floor or is it sufficient to set the batteries on 4 or 5 2Xs with the sides and front attached?

2. Back - do I need a separate plywood back? The 3 sided box would sit againsts the wall of the container. I'm thinking without the wall and plywood floor, I'd have better air circulation, less potential heat buildup.

Any thought, comments, suggestions?

David

niel · March 2006

Re: Newby's 2nd system in Hawaii

using 2x's is fine as long as the gaps aren't large between the boards as the weight of the batteries could cause the case to warp in some instances. open back seems ok to me just as long as the weather won't reach it and people can't reach it.

System2 · March 2006

Re: Newby's 2nd system in Hawaii

I started drawing a Battery box and have it put most of the way together. I went to home depot today to get hinges and handles for the lid. I used treated 2x4 and ran across the bottom at the ends and middle of each battery. Three batteries across and three long. I put a pc of plywood on the top of these 2x4 feet and built a frame using 2x2 and put plywood sides and ends with the top tapering 1 inch from end to end, 4 foot long. I used silicone on every seam to make sure no fumes could get out nor anything in. This way if there is a leak the bottom would be a built in tub. 1.5 inches up from the bottom far side corner from I will put an air in put tube using 2" PVC and run it out through the outside wall. On the top corner other end of box I will do the same and run it out through the out side wall. This is an inside box but could be put outside if I would put roofing on it and paint it pretty good. Or just put siding on it. I got 3/4" wide by 3/8" thick foam strips for the lid to close on to keep the fumes in. This way if the wind blows back in the top outlet it will just blow it back outside from the bottom tube. Now the part I am working on is trying to find a connector to use for the inverter and charge control cables through the wall of the box. I noticed most people are using a box and running conduit. DANGER!! DANGER!! DANGER!!.. This would let the fumes go through the conduit to the controller and blow the whole mess up. If I can't find something I plan to just put holes through and glue them shut with the cables through them. has to be something some where.

I may have mine completed this weekend or the next.. Depends on if momma makes me to dancing or something. I dread moving the batteries putting the box there and then putting the batteries in it. My son-in-law will make a mistake and show up sooner or later. lol How are you moving those 315 pound batteries around?

niel · March 2006

Re: Newby's 2nd system in Hawaii

hey sounds like you're doing pretty good with it. as far as the conduit goes i'd just get silicon rubber sealant and calk the area of the wire opening and the knockout area to keep its integrity. you don't need to go overboard with the calking as you just need a little to seal it.
as far as moving 300+lbs batteries go don't call me. i really don't have the answer to that one. maybe somebody else that has similar batteries can chime in as to what they did.

sodamo · March 2006

Re: Newby's 2nd system in Hawaii

Jon

Instead of Niel's silicon suggestion (which is good, but a pain if future work is needed) go back to HD or an electrical supply shop and buy the gray putty stuff made for this type application. The one I got is called Duct Seal, think the cost was around a $1 for a stick about the size 4 sticks of butter (2x2). I used it to seal around the wired from my PVs into the conduit. My Dad was an electrical contractor and I remember we used it to seal around entrance cable. Plug both ends of conduit. Unlike silicon, you could remove this later if you had to do something with the cables.

As for manhandling the batteries, being as Niel won't be available, my second best helper is my tractor. I have a boom pole that mounts to my front end loader. I have a nylon loop (2500 lb capacity I think) that I can slip through the eye of the boom pole and under each of the handle. I can place each battery in the box (front panel removed) with help from my BEST helper, my wife. From there I should be able to make minor placement adjustments. Of course, I'll be taking pics of the process.

David

niel · March 2006

Re: Newby's 2nd system in Hawaii

jon,
there may be an answer by using an engine hoist or something similar. you could possibly even make one if you have materials that would stand up to the stresses this would give.

System2 · March 2006

Re: Newby's 2nd system in Hawaii

I am about to move my own batteries. I went with 6 Rolls 8CS25PS 820ah 8v 425lbs ea. So far I have only transferred them from one truck to another and have found they slide easily on two 2x4’s. As for moving them into the battery shed, the top of the battery comes off and the individual cells can be unbolted. I haven’t figured out how to get a grip on the cells to pull them out of the primary container, but will hopefully be figuring it out on the 11th when I install them.

System2 · March 2006

Re: Newby's 2nd system in Hawaii

That would never work for me.. If she was to scrach her finger nail clear coat.. well it just won't work. lol I was just wondering how you had planed to move them around. My batteries are only 85 to 100 pounds each which will be a small job to move them about 12 foot out of the way so I can put the box in place and then will have to bring them back and pick each one up about 18 inches to clear the box wall. Not a big problem just a little rough when done by one person. I do have a two wheeler and a 30 year old son inlaw..

Make sure you post those pics some where..

sodamo · August 2006

Re: Newby's 2nd system in Hawaii

Well, this system is finally installed and online :-D :-D :-D

I'm sure we have some tweaking to do, but it's really great to run my tools now without first starting the generator. Being as we are still building the house, there isn't all that much load yet, in addition to running the usual assortment of power tools, I did put a dorm sized reefer in the now roofed garage so we can have cold drinks.

System as installed:

36 Kyocera 125 watt PV panels wired into 4 panel arrays at 48 volts. The 9 arrays (approx 26'X15') mounted on south facing roof of my tractor/utility shed.

12 Rolls/surette 4ks25, 1350 amp batteries wired as a 48 volt bank, in a ventilated plywood enclosure.

Outback PS4 panel for future expansion, currently with 2 MX60 charge controllers, 2 fx3048 inverters, mate, various other dodads.

I'll post a link to some pics if any interest.

David

niel · August 2006

Re: Newby's 2nd system in Hawaii

congratulations on your system and i'd like to see some pics as i'm sure others would too.

System2 · August 2006

Re: Newby's 2nd system in Hawaii

holy cow patties 4500 watts of pv. just thinking about
it makes me drool :-o

brad

sodamo · August 2006

Re: Newby's 2nd system in Hawaii

Link to pics: http://community.webshots.com/album/468915553RbjdnV/17

If interested, nearly uptodate construction pics precede solar pics.

David

niel · August 2006

Re: Newby's 2nd system in Hawaii

the pvs didn't show up too well in that first pic due to pic at dusk i suppose. hey the city(which one?) showed up on the left though. nice view.

Brock · August 2006

Re: Newby's 2nd system in Hawaii

Wow, nice!

sodamo · May 2016

Wow, hard to believe it's been 10 years.
made several updates to system, reflected in my signature.
Time to evaluate replacement battery bank.
would like to look at newer technology like Lithium or the Aquion, but may be better to wait a few years and hope prices and the technology improve.
An interim solution may be some Hawker 2v batteries available at a reasonable price that should last 5-6 years, longer perhaps now that I'm smarter. Ahhhh, decisions, decisions, decisions.....

mike95490 · May 2016

The Aquion was just rebadged and capacity decreased, so it may not be a good option any more.
My advice would be a minimal lead acid and revisit the choices in 3 years ????

sodamo · May 2016

Thanks Mike
I do have an option of getting the Hawker 2v 1600ah locally. These are taken out of service by a tourist submarine after a set period (forget if 1 or 2 years). Should last me at least 5 years if I go this route.
Would like to learn more about your NiFe. I see another member in Hawaii either has or waiting for them. I'd have to go with the 40 unit option, sounds like a big footprint.

Dave Angelini · May 2016

You won't have to wait as long as Mike says. I am beta testing some now and there should be some 48V options in the fall.
Next fall there will be something very, very, very, special! I think!

sodamo · May 2016

Thanks Dave
was hoping I could go another year or two, but batteries are falling into 45+ every night regardless of how many hours they may be 100%, 54 range during the day. Unfortunately we just went through a period of bad generator support, overcast rainy weather,aggravated by fact I wasn't here for a month and the on site people just did best they could, but the batteries suffered.
So far my most cost effective option appears to be the Hawkers at $250 each. We just use too much power to go small for a year or two.

Dave Angelini · May 2016

Yeow 45 volts! Lights out at 44! Good Luck!

sodamo · May 2016

So, latest development
looks like I can get NiFe cells directly from China. From the pics, sure look to be same as available from US sellers. Price would be $505 for 1200ah per plus shipping. Appears to include bus bars etc that the US retailers show. The only difference I see is the name stamped on the container. Thoughts? opinions? Etc? At 69 yo, the prospect of a 30+ year battery is enticing. While twice the cost of the Hawkers I shouldn't have to replace again. While I could look at less ah and maybe save some $, I seriously doubt my usage will be declining and may even increase as I get older/lazier.

Dave Angelini · May 2016

You read what I wrote. I think you would be rolling the dice but it is your money and sweat.
If you seriously believe that an offgrid battery will last 30 years I have some investment advice for you and reasonably fees, lot's of them!

Question who is your local dealer who will support you? Some guy in china? Wait for the Big's to sell you this technology. It is coming!

One of the things I do for my solar clients is teach them how to use less energy when they want to (bad weather) for example.
Most of them with large systems like you have can get by on 6kwh when the want to and burn over 50kwh for all the things people use electricity for. Some of them in the Islands do not need a generator.

sodamo · May 2016

Dave
sounds like about same level of support I get now

i purposely bought my generator from a company in Phoenix that builds them based on his assurance the extra dollars were buying support. With the exception of this last fiasco where it took them 6 weeks to figure out they did have a water pump in stock they have proven themselves near worthless. When I had an l1-l2 imbalance problem they insisted it was strictly on my end until I documented that problem existed independent of my outback and didn't exist with my backup generator. Had the rewire the alternator but wife's washer and microwave still don't like it.

As for usage, yup, we can get down if needed, turn off the spa, the extra refrigerators, etc etc, but then we are talking survival, not normal day to day living. I have a neighbor who boasts of his great dual voltage AC/DC system, but then he lives alone except his cat, and I doubt he has ever had 2 lights on same time, not exactly the lifestyle my wife signed up for.

Newby's 2nd system in Hawaii

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