A quick explaination of my solar system

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The usual. As I have two large solar PV systems here, and my lab assistant just put one in, and others are interested in things like this, here's where that stuff goes. This is mostly for things that work now, not "gee someday a fusor will do this" -- we know that, but it's not someday yet.
The hope is to save anyone embarking on this sort of thing a lot of wasted time and money, as at least I have been off the grid since 1980 and have had a lot of practice (and made mistakes you won't have to).

A quick explaination of my solar system

Postby solar_dave » Tue Aug 21, 2012 5:03 pm

I have a 12.5 Kw grid tie solar system which consisted of 72 175 watt panels and a pair of PVPowered 5200 inverters.
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I had to upgrade my service entrance to dual 200 amp panels with a 400 amp line from the transformer to comply with NEC code.
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The wiring for the panels enters my attic via a weather head and runs to a combiner box with fusing in the attic. The panels are connected in 8 strings of 9 panels. The DC then heads to the DC disconnect between the inverters.
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There is an AC combiner next to the panels that takes the AC and combines it into one line to the Mains.
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The billing system for my utility allows for net metering and provided $3 a watt in rebates for the system when I installed. At that time the install was about $6 a watt. The interesting thing about the net metering plan is that the watts generated can only be used in the TOU time frame that they are generated. So I still get to buy off peak power from them. I currently have about 1500 kWh in my on peak TOU bank. Most people load shift to off peak to reduce costs, not us, we load shift to midday to get that power for free. On Dec. 31 each year the utility will pay use $0.065 a kWh as a credit on our Jan. bill. This year it was enough to cover all our fees and such until mid year.

If you have any questions feel free to ask.
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Re: A quick explaination of my solar system

Postby Doug Coulter » Tue Aug 21, 2012 8:20 pm

That's a truly gorgeous setup Dave - thanks for posting it! If Chris checks this out - remember, Dave is running two electric cars and air conditioning in the desert off this, and it's not ultra huge. You might find this stuff more practical than you first thought - you do have to own your own roof, however. Where I live, I calculated it takes about 200 sq feet of panels to just do the car, once a day, on average. You might need a little more, but most roofs have that to spare (mine is 512 sq feet looking straight down on it). The cars are the biggie here, since I have a very light load for HVAC, and the fusor and machine tools are only run now and then - they eat kW, but not many kWh.

Solar just rocks. Freedom!
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: A quick explaination of my solar system

Postby solar_dave » Tue Aug 21, 2012 9:45 pm

I have a few hobby machine tools as well, a taig cnc mill, a Seig super x3, a drill press , a 9x12 lathe and a 6x18 Boyar Schulz surface gender. Also a Lincoln stick welder, a cheap wire welder and 5 hp compressor. they aren't used daily or even weekly, just my toys. I worked as a tool and die maker for a lot of years before I got into computer support.

I am fortunate in the amount of isolation I get, in turn this place has a pair of 3 ton Trane AC units and a 36,000 BTU mini split on the new building that I only run to the max when I am in the shop.
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Re: A quick explaination of my solar system

Postby solar_dave » Wed Aug 22, 2012 11:28 am

Just as an FYI, we are planning a 3290 watt expansion of the system onto the new workshop/office building on the back of our lot. The reason for this is sort of 2 fold, first we want to be net zero with the utility (we are really close now but the second Volt has pushed the ragged edge), second our consumption is going to go up as I get more free time to play in the shop. At some point I will post some pictures of the shop as well in the proper forum.

The add is going to be with Enphase micro inverters because of some shading that will happen near the winter solstice. The line will be run to the existing AC combiner and joined to the back feed there. Really this may still be an issue as NEC only allows for a 20% back feed over rate on the panel bus bar. We have a 200 amp panel with a 175 amp main breaker and a 60 amp feed in breaker currently. The max allowed technically would be 240 amps of total feed in to that panel. 175 + 60 = 235 amps. The pair of PVPowered inverters will actual generate 23 amps each max, total combined well under the 60 amp breaker. The 3290 watt panels will generate at most 15 amps @ 220V. I reality it will never get there as STC on the panels can never really be achieved. The problem lies in the combiner which has 2 30 amp breakers for the existing feed in. All is OK with the NEC now but if I add a 15 amp breaker to the combiner panel then I have to upgrade the feed in line to the main panel to the next common breaker size, most likely 80 amps. This pushes the combiner feed in over the bus bar rating. One workaround would be to decrease the panel main breaker to 150 amps and this may be my only solution. I think this will still be OK as that panel only has 2 loads attached, the sub-panel for the new workshop office building (125 amps) and the sub-panel for the Volt chargers (60 amps).

Code monkeys, what you going to do? You can see the new building location is in the lower left of this view of the property.
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Re: A quick explaination of my solar system

Postby Doug Coulter » Wed Aug 22, 2012 11:49 am

You could always break down and do what I do - batteries and a subsystem not grid tied (or load shaving like the other Dave does). Rats, I wish that Volt battery system would become available to us, I'd buy a few in a heartbeat for my system (especially at the current listed price!). As we know, it's not just the cells, it's that whole system for temp control, and for balancing charge between all those cells that matters. Those are so many miles ahead of my submarine lead acids it isn't funny, and it would be like adding around 30% more panels. I probably wouldn't even need the capacity I have now, in either panels or batteries, since I can fully cycle the Li types, but not my lead acids - kills them pretty quick, as I found out before I learned about this.

The advantage is that if you're just using the power straight - you don't go through the wiring the building inspectors care about, and if you load-shave, you're actually reducing the current to the grid in either direction. Say you're using 50 amps in your house, but creating 40 - then the wires out to the power co only see the difference - 10. That's not more current, it's less! Not that code was written by guys who really understand what is going on. IT's more like - make things unlikely to fail in edge cases, and reduce it to a check off list for people who just put wires under screws and really don't know what's happening, all by rote.

This for example is why you can't use solder under code - it's not that it can't be better than mechanical connections, it's that your basic sub-IQ building inspector can't tell a good solder joint from a bad one! And in that case, the guys who wrote the code know that.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: A quick explaination of my solar system

Postby solar_dave » Wed Aug 22, 2012 2:22 pm

I agree on the Volt batteries, I do sort of load shave now by running most of my high load stuff in the daytime, pool pump, most of the Volt charging, laundry, cooking. This is why every time I approach the utility about changing TOU plans from a 9AM to 9PM plans to a noon to 7PM plan they say it will cost more money. Really I think it will cost less and reduce my off peak purchases from them. hmmm conflict of interest to boot. That is why I have taken my TED monitoring system and started to collect the data so I can analyze the load profiles. I think I need about 60 days worth to get the calculations to be accurate. We shall see. The problem is the 9AM to 9PM plan is a grandfathered rate, I change and I am unable to return to it. :evil:

Edit:
While batteries give you lots of freedom, they are a PITA to maintain, cost a lot up front, have a finite life (assuming you don't screw up and kill them) and generally require a good thermal environment to live in. My grid is very dependable, just expensive. In 15 years I can only think of a couple of outages lasting at most an hour. Volt batteries might be a real game changer, I could envision a stack of them replacing the grid for most people. However My daily solar in mid summer is inadequate to support the operation of this place. The solar in summer produces about 63kWh, the operation draws on a peak day 135 kWh and most summer days about 100 kWh. It is the spring and fall times where I produce all my excess kWh to carry my summer loads.
Last edited by solar_dave on Wed Aug 22, 2012 2:40 pm, edited 1 time in total.
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Re: A quick explaination of my solar system

Postby chrismb » Wed Aug 22, 2012 2:26 pm

Doug Coulter wrote: If Chris checks this out - remember, Dave is running two electric cars and air conditioning in the desert off this


I'd love to set up a system like this, Doug. This is very neat. Nicely done, Dave.

In my case, the roof of the house is, unfortunately, facing dead east-west. Combined with the fact that I am far from a desert and have a 'cubic' shaped house with a small footprint (thus roof space) I think the due estimate calculation on my house (with an online estimator calculator) was something like 750W av power from the west facing side. The east facing is shaded by trees for most of the morning, so that's no good.

if I move, I'll be sure to be mindful of valuing a south-facing large roof, with a good sky view, in the buying decision. Can't see that happening any time soon, but feel free to send in the well-paid job offers from State's side, in a place I'd be able to afford the real-estate, and I'll be following you guys' lead!!!
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Re: A quick explaination of my solar system

Postby Doug Coulter » Wed Aug 22, 2012 2:43 pm

I hear ya loud and clear. I justify (rationalize?) my stuff not as a green thing, but as a sensible thing, and my mantra is freedom. When you depend on an outside company/personality/interest, you're not as free (in the freedom sense, not the free beer sense) in my opinion. You might pay more, but you get something for having paid more - more personal freedom to not need further income to have what you want.

In my case, going solar was one of those gut decisions I then rationalized (man is a rationalizing, not a rational, animal). I got really screwed over by a power company while I lived in DC with their estimated then real bills - had I known what I was running up, I'd not have chosen to use that power, but too late (4 months) I get hit with a huge AC bill, just before heating season and that bill, and threats to my credit rating, which used to matter to me (no more). So, out of not liking that deal, and being an EE - "if not me, who is going to be the early adopter", and having a fresh start here in Floyd, it all just came together, and I'm now glad it did - I need make no excuses anymore. I DID have some hardship along the way - the solar was all I had and quite often not enough to do what I wanted to be accustomed to, but hey, even then the money saved allowed me to have a better lifestyle than otherwise, and take a longer break from "engineering slave labor" to recuperate from my burnout. So, all good from my POV.

Everyone's mileage will of course vary on this one. I am reminded of a new-age parable that goes like this.

The truth (nirvana, heaven) is at the top of this mountain, with people all around the base. The Catholics are shouting "go west", the Buddhists are saying "go east", the Jews "go north" and so forth and so on.
Perhaps the Vikings are saying go southwest. You get the idea.

Each is correct for some of the people involved, because depending on where they begin, going west, east, north might take them to the truth. But the real message, which is rare indeed, should be "go up".
Which compass direction that is might not be as relevant as where you are at the moment. Up is the same way for everybody involved, though it might be north for some, south for others.

I am further struck by people's resistance to simply pulling up stakes and going to where things would almost certainly be better for them. Heck, I'm guilty of this too - I was born in DC and am still in VA, though as far from DC as you can get in VA. Yet people continue to live in places where nature really isn't their friend most of the time (or their government, or other things like that), and this kind of thing won't/can't work or be economical for them, and stick with the devil they know - even though that devil might be quite harsh in other ways too.

It's a head-scratcher for me, anyway, and I'll probably figure it out at some point just from my own innards - why am I still near my place of birth? I rationalize it this way at the moment. My jazz band toured all over, and believe me, some of the places we went were pretty darn nice. I was even offered a cherry job doing power for a small island in the Bahamas on one trip. But when we toured here for a festival (kind of our own woodstock), the people I met - it was clearly "home" - my tribe, where I belonged, out of a lot of other places even nicer on the surface. So here I am, and I got lucky in that the climate, the government, etc, are mostly on my side here.

Yeah, solar ain't gonna be great in UK, famed for its bad weather. I'd be wanting out for the bad weather reason alone. If I have to live in "the world of indoors" all the time, I think there might be better places that have better tradeoffs in other things, but that's just what I think, and it might not be true for everybody. So I keep saying "go up" and hope people know which way that is!
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: A quick explaination of my solar system

Postby solar_dave » Wed Aug 22, 2012 2:59 pm

I found out which way was up over the years. It really isn't a place so much as a state of mind, and what it takes to get that. I was born in Michigan, with all the economy ups and downs of the auto industry in the 70's and the lousy weather in winter, so in 1981 I set off for Denver, better climate, much Reagan defense dollars being spent made for a comfortable life. Then Denver got the economy blues at the end of the Reagan era. I hung on there for a few more years but it was a down hill slide, then I started looking again. I had choices in 1997 and Phoenix seems like a nice place, clean, reasonable weather 9 months out of the year, low cost housing, etc. It has played out great, wish I had done it first instead of Denver but it is all in your state of mind.

I am now counting the months to retirement, hoping that plays out as planned.
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Re: A quick explaination of my solar system

Postby Doug Coulter » Wed Aug 22, 2012 3:55 pm

Hot dang, Dave, that's cool! I've been retired for nearly 10 years now, kinda, and I'm only 59 at the end of this month. We folded my product development consulting company voluntarily, as after so many years of 80 hour workweeks, even stuff you love, burnout is inevitable. We just sat down one day, having almost had an actual argument (what we did brainstorming looked like heated argument to others, but we knew better) - and said hell, we're all rich, no time to spend it, why not take a break? So we did. A couple years later, the other guys were running their own similar businesses. You just can't quit once you get the bug, it seems.

Guess you can't really retire if you're for real - you get bored, lose your reason for living, and you kinda have to find something else that makes you want to get up and go everyday. For me, it was building the farmstead up, automating things (hopefully) faster than my health went downhill to be able to do them manually, the fusion trip (which I'm still doing full blast), and designing things just because I want one and its fun to do. I trust you won't be one of those people who die right after they retire because they lose their lust for living - you don't seem like the type to fall into that trap.

I did (over did?) the machine shop thing as a reaction to most of my life being consumed previously just creating bits - IP - designs, for things that live in closets and if anyone even becomes aware of them, I failed - stuff with a lot of 9's reliability, in other words, infrastructure things. Or things like codecs now used in cellphones and the like. I wanted something I could point at and say "I did that", hence the tools to do just that.
I now understand why machine shops and inventors don't get along that well. It's all setup! Onesies they have to charge so much for it gives them a bad rap, but that's really the deal - I can crank out 100 of something for very little more than the first one...Much nicer when it's just your own time involved and you can just do it for the sheer enjoyment of it all.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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