# Components for a new PV system



## K.B. (Sep 7, 2012)

Now that I've finished the rough electrical and framing on the new house, I am getting ready to pull the PV permit this week. I'm looking forward to working on the PV system this summer.

I wanted to post the list of general components that I am thinking of using for the system and see if any of you would be kind enough to provide feedback or suggestions.

My location is in southern OR (4-5 insolation hours on average). December/January is typically very cloudy, so from other examples in the area, I expect to use a generator daily during those times. The house is a high mass, passive solar design.

Based on an estimated daily load of approximately 4000 watt-hours, here is the list of the main components:

9 - 255Watt SolarWorld modules (3 strings of 3 panels mounted on standing seam metal roof; full sun exposure):
http://www.backwoodssolar.com/products/solar-modules/solarworld/solarworld-255-watt-mono-module

Outbacks PV8 Combiner box:
http://www.backwoodssolar.com/produ...combiner-boxes/outback-8-circuit-combiner-box

Outback FlexPower One power center (FP1-2)
http://www.amazon.com/Outback-Power...e=UTF8&qid=1403544543&sr=8-4&keywords=VFX3648

8 - Trojan L16RE B 6V batteries:
http://www.backwoodssolar.com/trojan-l16re-b-6v-370ah-battery

I'm tempted to go with a string of the Trojan T105RE's to start, since this will be my first PV system, but I think the extra capacity of the L16RE B's will be necessary.

I've had some preliminary discussions with the building dept, and they will also require active ventilation of the battery system while charging (battery room is located inside the house). I have not found a reasonably priced box or other enclosure that is UL listed at the moment, so any pointers in that direction would also be helpful.

Thank you very much!

KB


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## TnAndy (Sep 15, 2005)

Good choice in equipment if you ask me. 

You'll love the Outback pre-wired power center....hang it on the wall, plug in your solar in from the combiner box, runs the wire to the battery bank, plug up your 120vAC out to your panel, ground it, and you're DONE. It's as close to plug and play as you can get. I did one for a buddy's off grid place, and I'd never go any other route again. We used the same Flexpower panel on his, along with 6-245 Solarworld panels, and he gets 4-5kw/hrs day out of it here in East TN....and we have a lot of cloudy weather also in the winter. He runs a small Kubota diesel generator when needed.



















As for a battery box, everybody I've seen usually builds a tight plywood box, then vents it to the outside.

Panels, you can't go wrong with Solarworld, but you can get them a bit cheaper elsewhere....for example:

http://www.solarsyz.com/solar-panels/solarworld-sw260-mono.html

I'd also give a serious look at Suntech ( also made in the USA ) 295w panels for $238 (same website as above)

Do you plan to use racking to mount the panels, or the clips that go directly on the standing seam joints ? Saves money, and no roof penetration.


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## K.B. (Sep 7, 2012)

Thanks Andy - I appreciate your feedback and the link to the better deal on the Solarworld panels. I've tried to factor in a lot of your recommendations from my reading over the past year.

I'd love to put a homemade battery box together and vent it through my back wall. I sent a sample picture of a box like that when I submitted my initial house plans and the reviewer came back with the request to make sure it was UL listed... The electrical inspector has been pretty easy to work with so far, though, so maybe he will be willing to work with me if I can come up with a liner or tray to put in the box that is approved material.


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## TnAndy (Sep 15, 2005)

KB,

I'd sorta be surprised if you can come up with a UL listed box. There are metal and plastic enclosures out there, but I don't know if I've seen a UL listed one.

Also, on the batteries....check your local Deka dealer for those L-16's. They run around $250 each here, versus the $350 Backwoods has on the Trojan. Also, if you can buy local, shipping would be less of a factor.


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## K.B. (Sep 7, 2012)

Thanks again for the tips. I'll check on the Deka brand batteries, too.

Sorry I missed your question re: the panel mounting. At this point, my plan is to mount the panels using the clips on the standing seams of the metal roof. If I need to, I can put a rack or two up right behind the house on the south facing slope.


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## wy_white_wolf (Oct 14, 2004)

I've seen old chest freezers used as battery boxes. Just vent the lid at the highest point to the outside.

WWW


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## K.B. (Sep 7, 2012)

That would be a very good option if the inspector will accept it - thank you for the idea!


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## Dixie Bee Acres (Jul 22, 2013)

White wolf may have the answer, I thought about the chest freezer before.
I don't have solar yet, but have been trying to plan it out for a while.
I thought a chest type freezer, with a couple computer case fans venting through a duct to the outside, fans would be wired to only run while the batteries are charging.


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## Gray Wolf (Jan 25, 2013)

I built a plywood box and then painted the inside with three coats of epoxy to make it leak proof if a battery leaked in the box
. Then 2" conduit out the top for vent and 3" hole up about 6" from the floor for i take air. Battery room is in the house. It passed inspection.


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## K.B. (Sep 7, 2012)

Here is a link to a brief Home Power article describing a box that sound similar to your setup, Gray Wolf:
http://www.homepower.com/articles/solar-electricity/design-installation/battery-box-design

The EPDM liner in the bottom portion of the box is another interesting option. I have some extra liner from my EPDM cisterns that could be used instead of a tray or sealant.

Regarding the fan/control, I need to look and see if the Outback system includes a relay for direct control of activating the fan during charging.


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## PorkChopsMmm (Aug 16, 2010)

The Outback charge controller can be programmed with the AUX command to run a fan when the batteries are being charged.

Nice set up -- wish I would have gone with the Flexpower kit. I I pieced all of my kit (everything Outback) together. We started with 6 240 panels and 8 6V GC2 batteries. I eventually increased to 12 240 panels and 16 GC2 batteries. Life is good now but we have a lot of loads. Take pics of your battery box -- whenever it passes code!


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## K.B. (Sep 7, 2012)

Got the line drawing/plans for the system reviewed and approved today. The reviewer was ok with a homemade box as long as it was sealed/vented.

Time to start ordering the components!


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## PorkChopsMmm (Aug 16, 2010)

Great!


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## Solar Geek (Mar 14, 2014)

Last PV system (6.2KW) we had the "coffin" wooden box handmade by the PV installer as part of the system- it passed no problems.

This time with our 10KW system, our guy used the enclosures at http://midnitesolarfaq.com/index.php?PHPSESSID=866d530cf7887aea6ab25ea0a24e808f&topic=16.0

Since we got 1/3rd back on tax credits and some $$ from the state program, it came in quite comparable. Handmade would have taken up too much space.

We also have the Outback system and love them.


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## K.B. (Sep 7, 2012)

Thank you for the link to the battery enclosures. I will keep the link as a fall-back in case I have trouble with the homemade box passing. Glad to hear you are happy with the Outback system, too!


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## K.B. (Sep 7, 2012)

Just got a quote from a local battery dealer for the Deka L16 batteries at $272/each. Not quite as good as Andy's $250 deal, but the best I have found so far.


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## TnAndy (Sep 15, 2005)

K.B. said:


> Just got a quote from a local battery dealer for the Deka L16 batteries at $272/each. Not quite as good as Andy's $250 deal, but the best I have found so far.


In fairness, that price was from 3-4 years back, when my off grid buddy bought his from the local Deka dealer.....I haven't shopped them since then......so given inflation, which officially, of course doesn't exist, that price is quite comparable.

I bought a set around late 2007, and 8 of them ran me around $1700 out the door (tax and all), but I knew lead prices went way up not long after that. I sold that set couple years later for one gold Kugerrand (about $1,000 at the time), and replaced it with a 1200amp/hr AGM telecom set that a buddy of mine at a cell phone company ran up on.


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## K.B. (Sep 7, 2012)

Excellent... with no sales tax here in OR combined with the rep saying they would not hit me with a core charge for a new system, the price sounds really good. Looks like I can get the battery order completed this week.


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## TnAndy (Sep 15, 2005)

Good deal ! Hope you're up and running before too long.


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## Warton (Jun 24, 2014)

Hi,

I'm glad to hear your plans for the new system have been approved! So much to do with the new pv system. Well, if I can recommend you something it will be this app http://easysolar.co/ which will be a great help to you. It provides you with some simmulations and financial analysis. And you can have it on your smart phone or other device with the Internet connection. Oh, and it also uses the cloud technology, you can also use advanced algorithms that calculate the output energy production, you will be able to verify the irradiation level or check the possible shadowing, and apart from your disc, your projects are also saved inside the cloud, so getting back the data in the event of a breakdown of your device becomes easier.
And good luck with all the installations!


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## Peasant (May 18, 2013)

K.B. said:


> Just got a quote from a local battery dealer for the Deka L16 batteries at $272/each. Not quite as good as Andy's $250 deal, but the best I have found so far.


Trojans are cheaper here in the Portland area, recently picked up two T-105s for $140/ea. $140 for 225 ah = 62.2c/ah. The Dekas are 370 ah, i think, which puts them at 73.5c/ah. But the Trojans require a core charge, which probably evens it all out.

Besides, Sin City is a good ways from southern Oregon 

Are you having someone install it? I've been building my little off-grid solar electric system for about a year now, got federal tax credits in 2013 but not state since it's been strictly DIY. State requires a licensed installer.


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## K.B. (Sep 7, 2012)

Peasant said:


> Trojans are cheaper here in the Portland area, recently picked up two T-105s for $140/ea. $140 for 225 ah = 62.2c/ah. The Dekas are 370 ah, i think, which puts them at 73.5c/ah. But the Trojans require a core charge, which probably evens it all out.
> 
> Besides, Sin City is a good ways from southern Oregon
> 
> Are you having someone install it? I've been building my little off-grid solar electric system for about a year now, got federal tax credits in 2013 but not state since it's been strictly DIY. State requires a licensed installer.


Thank you for the price comparison on the Trojan's. Do you happen to know the local cost of the Trojan L16RE B's? I'm down by Medford, so it would be quite a drive up there 

I'll be doing the installation myself, but I have a family friend who is an electrician to help out when needed.

From reading your posts it sounds like you have a nice system. Thanks again!


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## Peasant (May 18, 2013)

K.B. said:


> Thank you for the price comparison on the Trojan's. Do you happen to know the local cost of the Trojan L16RE B's? I'm down by Medford, so it would be quite a drive up there
> 
> I'll be doing the installation myself, but I have a family friend who is an electrician to help out when needed.
> 
> From reading your posts it sounds like you have a nice system. Thanks again!


I got my batts from Mike's Auto Parts in Beaverton, looks like they have Trojan L16s for $300, maybe with core charged waved if bought in bulk (hard to tell from ad).


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## K.B. (Sep 7, 2012)

Very interesting - thank you for posting the info/link. I am still working on my learning curve to decipher the varying types of the L16 types. I will read up on it.

Regarding the overall system, I received my first shipping notice today for some of the components. I will update the final list of components that I chose to order in the next day or so.


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## K.B. (Sep 7, 2012)

The solar panels arrived today - wow that was fast considering they just shipped on Tuesday!

I was a bit nervous after having read many horror stories regarding panels damaged during the shipping process. In my case, the pallet that the panels were stacked on was broken at one end and some of the plastic corner spacers were deformed, but the only visible "damage" are a few small distortions/permanent smudges on the glazing of a couple panels. Hopefully it won't affect the overall performance. 

I ended up going with the SolarWorld 280 Mono panels:
http://www.civicsolar.com/product/solarworld-plus-sw-280-mono-280w-mono-slvwht-1000v-us-solar-panel

They are beautiful!


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## K.B. (Sep 7, 2012)

Here is the updated component/supply list so far:

9 - SolarWorld SW 280 Mono 280W panels:
http://www.civicsolar.com/product/solarworld-plus-sw-280-mono-280w-mono-slvwht-1000v-us-solar-panel

1 MC4 Tightening/Unlocking tool:
http://www.civicsolar.com/product/multi-contact-mc-16

1 - Outback Flexware FWPV8 Combiner Box:
http://www.civicsolar.com/product/multi-contact-mc-16

4 - Midnite Solar 15A 150VCD Din Rail Mount Breaker:
http://www.civicsolar.com/product/midnite-solar-mnepv15-15a-150vdc-din-rail-mount-breaker

3 - MC4 Extension Cable (100 ft):
http://www.civicsolar.com/product/mc4-cable-extension-10-awg-use-2rhw-2-100ft

25 - S-5-N mini clamps:
http://www.civicsolar.com/product/s-5-n-mini-clamp-standard-seam

25 - S-5-PV Kit clamps:
http://www.civicsolar.com/product/s-5-pv-kit-universal-grab-and-ul-grounding

1 -Outback FlexPower FP1-2 (VFX3648) prewired system:
http://www.civicsolar.com/product/outback-flexpower-one-fp1-vfx3648-pre-wired-system

I ordered a spare of each of the clamps and the breakers since they were pretty affordable.

I am still working to finalize the batteries and cables, but at this point, I think the Deka L16's mentioned earlier in the thread will be ones I go with.


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## K.B. (Sep 7, 2012)

The Outback panel arrived yesterday. Everything appears to be in great shape. 

I tested the output on a few of the SolarWorld panels this past weekend and they were within 5-10% of spec on a hot day, so I am counting that as a good sign.


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## Peasant (May 18, 2013)

That's a really nice system you're putting together KB, if I ever build a house-sized system I'd probably go with similar components. 

I wanted to go with SolarWorld for my little RV/cabin sized system since they're based in Oregon, but they only manufacture grid-tied panels. Couldn't justify the expense of an MPPT controller for a system this small (632W panels + 2 golf cart batteries).

Outback has an excellent reputation as far as I can tell based on the solar electric forum I'm active on (NAWS). 

I am a bit concerned about one thing, though. I just looked over your numbers and I think you may be a bit "under paneled" or "over batteried,â however you want to think about it. With the nine 280W panels and eight L16s, you get you a ~7% charge rate if we use a 77% derate.

My little 12V system (still in progress) will be four 158W panels + two 6V 225 ah batteries. That gives me a ~12% charge rate, right in the 10-13% window Trojan recommends for their batteries.

Not saying my system is perfect, especially since I haven't tried it yet in winter, but I've run my numbers by some pretty knowledgeable folks at the NAWS forum, and they confirm they're in the ballpark. Sizing is one of the harder things to do with solar electric systems, and a lot depends on how one is using the system and their local insolation.

I based my sizing numbers primarily on my daily usage, average winter sun-hours (1.9/day), and a 10-13% charge rate for my batteries. For Oregon winters it strikes me that being âover paneledâ is better than being âunder paneled.â I ran a generator all last winter, it was an expensive pain in the butt.


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## K.B. (Sep 7, 2012)

Hi Peasant - thank you very much for the feedback and particularly for running through the numbers. I appreciate the perspective of people with experience in using and maintaining their PV systems. I am very much on the steep part of the learning curve.

The primary issues in sizing the components for the system I am working on (starting with) have been based on the estimate daily load (4000 watt-hours) and budget. I am hoping the 2500 watt array should be able to produce the ~5000 watt-hours necessary to keep a balanced energy budget (factoring in system inefficiency/losses) more than 2/3 of the days in a year in my region. A backup generator will be necessary to supplement the charging during the rainy season. I have a nearby seasonal stream that I hope one day could provide charging via microhydro, but I am not expecting that to be a factor anytime soon.

The 8 Deka L16 batteries (370 AH; 48V system) provides a theoretical ~17000 watt-hours of capacity, as I understand the calculations. I like the size of this battery bank because it seems it will allow us to use our daily 4000 watt hours on days with no charging and still keep just above 70% charge capacity (less than 30 depth of discharge). Not much of a buffer against a run of cloudy days, but it is what I can afford right now.

Regarding charging rate, I estimated that the MPPT charge controller would provide ~40 Amps during peak charging hours, which seemed like a good rate based on the 370AH bank capacity. The system inefficiency may bring this down, of course. It sounds like your estimates are that it will be reduced quite a bit, is that correct?

Again, I appreciate your help and any thoughts you can share. The numbers I have listed above are based on my novice level of understanding and theoretical conditions.


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## Peasant (May 18, 2013)

The 77% derating is a figure from the two posters at NAWS who's opinion I respect the most (BB and Cariboocoot). It's also about what I see on a good sun day. My panels are 158W each, but don't think I've ever actually seen 158W out of them. ~120W is typical when the batteries are in the absorption stage.

I'll use nominal 12V figures because that's what I use for my system, though I know your's will be 48V. Divide by 4 to get 48V figures. 

Assuming 77% derate, your panels should produce roughly 104 amps. If your daily load is 4000 Wh, at 12V that's 333 amps. 333 / 104 = 3.2 sun hours to charge your batteries.

There are also battery inefficiencies to account for (need to put in more amps than you take out). Assuming 5%, that would increase the sun hours to 3.4. Plus inverter inefficiencies and wire loss, the specifics of which will depend on your components.

Your system is sized about right for the average in most of Oregon (4 sun hours in my area). But not so much for winter. Sounds like you know this and are planning to use a generator to make up for it. I'd crunch some numbers and see if the money used to run the generator might be better used to buy more panels.



> The 8 Deka L16 batteries (370 AH; 48V system) provides a theoretical ~17000 watt-hours of capacity


Yep, 17,760 Wh to be exact. That's 22.5% of your daily load. One day autonomy if you only draw them down to ~75% (good idea). Two days if you draw them down to ~50% (OK on occasion but I wouldn't do it regularly).

What battery charger are you using to charge the batteries from your generator? And how big is your generator?


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## K.B. (Sep 7, 2012)

Thanks again. It is very helpful to hear how your panels are producing/charging given that you are in OR, as well. I think the southern part of the state has a bit more sun during the winter, but apart from a few lucky sunny weeks in winter, it is still very cloudy from Dec-Feb.

I am definitely interested in expanding the PV system with time. The outback system can handle additional panels so it should be relatively easy to add on to that part of the system. I think I will be stuck using the generator during a good portion of the winter though, even with an expanded array. I am very curious to see the seasonal differences in performance.

How much of a difference do you think the MPPT controller in the Outback system will make in terms of overall output efficiency?

The battery charger is built in to the Outback system (VFX3648) - 60A max, I believe. 

I currently have a cheap 5000W generator that serves well for construction purposes, but a Honda eu3000is generator is in the budget for the system once I get closer to having everything installed. Once everything tests out all right, my plan is to do a propane conversion on the generator.


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## Peasant (May 18, 2013)

K.B. said:


> The battery charger is built in to the Outback system (VFX3648) - 60A max, I believe.
> 
> I currently have a cheap 5000W generator that serves well for construction purposes, but a Honda eu3000is generator is in the budget for the system once I get closer to having everything installed. Once everything tests out all right, my plan is to do a propane conversion on the generator.


The VFX3648 has a 45 amp "Continuous Battery Charge Output." At 370 ah of battery at 48V, that would give you a 12% charge rate. That should work fine with a 3000W generator. 

I think closer to 20% charge rate when running a generator is better (for quick bulking). But 12% will certainly work and is better for longer battery life (and shorter generator life). Everything's a trade off.



> How much of a difference do you think the MPPT controller in the Outback system will make in terms of overall output efficiency?


I don't have any direct experience with MPPT controllers. I do know they're particularly useful in winter, when you'll be needing that extra solar output the most. 

From NAWS on MPPT controllers: 
"You typically get a 20 to 45% power gain in winter and 10-15% in summer. Actual gain can vary widely depending weather, temperature, battery state of charge, and other factors."


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## K.B. (Sep 7, 2012)

Thanks again for the additional info!


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## K.B. (Sep 7, 2012)

The FWPV-8 combiner box and breakers arrived yesterday. Looks like a pretty straightforward setup.


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## K.B. (Sep 7, 2012)

Reviving this old thread...

After quite a few months delay due to lots of business contracts and slower than expected construction on the house, I finally finished installing the first phase of the off grid PV system this weekend. 

The Flexpower panel is mounted and wired to the 48V battery bank, combiner box, and AC distribution panel for the house. Powered the system up for testing the house circuits and all seems to be working well. 

I will be working on the connections for the generator/AC input this next week (14 and 10 ga cables hanging to the right of the combiner box in the photo) and the active venting for the battery box when charging. Hoping to have the solar panels installed and connected within a few weeks.

Thanks again for all the help to the folks who offered up their suggestions and advice!


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## Gray Wolf (Jan 25, 2013)

Thanks! Most people don't post the outcome of the topic.


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## K.B. (Sep 7, 2012)

Thanks Gray Wolf! This system is still a "work in progress". I particularly appreciate all the tips and knowledge shared on this sub-forum.

I was able to get the wiring set up to use my generator for charging the system this weekend. I need to spend some time with the programming portion of the instruction manuals to make sure all parameters make sense. 

From what I can find for the 8 DEKA L16 batteries, the charging parameter ranges should be:
Absorb (bulk) 57.6-58.8V

Float 55.2-56.4V

Equalize 60.0 - 61.2V
(all assuming a room temp of 25C/77F - temperature coefficient = 0.072V/degree C)

Please let me know if these parameters do not seem in line with what you would expect for the battery bank. 

I also set up the Zephyr power vent for the battery box. I still need to get it wired to the relay on the panel and programmed for the charging parameters.


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