PV watts says

gww1gww1 Solar Expert Posts: 963 ✭✭
I have 5640 watts solar installed. It cost me $17500 for everything after taxes and including my wind, I did all the labor.

Pv watts says my system cost $0.35. If I added 2100 watts solar and paid what I did for what I already have, say $0.92 per watt and $500 for racking before taking 30% off for taxes, it would bring my cost down to $0.24 per kwh produced. This is because I would just be maxing out and maby a tiny bit above my current charge controllers and I already have the 15 amp breakers and room for them in the combiner box. Matching the panels may be hard. MX 235 watt panels.

Looking at this almost makes it impossible not to do except I really don't have the $2000 bucks to spare as I would have a very hard time replacing the savings.

It would be the cheepest solar I had ever did and bring my cost down on the rest. It would also stress my charge controllers but improve my chance of getting absorbs for my battery.

What do you think
gww

Comments

  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: PV watts says

    I think if your system is charging fine and you don't have additional needs, it is a waste. You make it seem as if having the ability to produce more is a good thing, but if you don't need it, you don't need it and it will just be wasted potential most of the time.

    Indeed I don't know who 'PV Watts' is, but Photowhit can do the math and will tell you if your system costs more and produces the same the cost for used Kwh will be greater...

    I thought we had discussed systems in the past and you were much cheaper than that?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Re: PV watts says

    The "New" PV Watts program, I think:

    http://pvwatts.nrel.gov/

    Of course, for off grid solar, you need batteries every 5-8 years or so (typical mid-range battery), new electronics (charge controllers, inverters, etc.) every ~10+ years, assuming the panels last 20 years, add a backup genset+fuel costs, and assuming you can only use ~66 to 75% of the available yearly kWHs available from the array--The $xx/kWH pricing will go a lot higher.

    One or two people here say their pricing for off grid power is $0.50 or less per kWH... But the usual number (when I do the math), seems to be $1-$2 per kWH. For seasonal/weekend cabins where you only use a fraction of the available kWH per day (i.e, 2 days a week, 3 months out of the year), that also makes the pricing rise too (use 50% of available solar energy means 1/0.5 or 2x increase in system costs).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: PV watts says

    Yes it gives numbers that are completely unrelated to off grid systems, Other than the available energy on a daily basis, and even those are skewed. Since you would have to make use of all available energy after losses and that is not practical. FWIW I'm one of those who believes I'm under 30 cents a Kwh, so for a laugh I ran the numbers and with 40 degree panels and 50% losses I got 17 cents a Kwh for the existing system as setup now and since I have 2.6Kw off panels to install yet, that I paid $1000 for a real laugh I added those numbers in and got down to 13 cents a Kwh! These are NOT real or practical numbers for off grid systems, there will be reoccurring costs as Bill pointed out, and you simply have to have waste above the system/storage waste.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: PV watts says

    I got all my solor for 92 cents a what. The inverters and one cc for 1500, It cost me $750 to build the mounting. All not that bad but the trenching, the ts60 cc that I don't use, the ghurd cc that I outgrew, windturbine, towers, experments, all put down as a dollar amount on a peice of paper says I have $17500 counting a recent $500 dollar inverter repair and after I got my taxes back. The only reasons it is so tempting is The 6 to nine days a month I can't run night time loads due to getting the battery sgs back up and I don't make hot water everyday now. Also it fits my system with out running more wire or buying more charge controllers. I probly won't do it (I don't feel like building more racking) but it would give me the most for my money that I have spent so for. At $0.10 a kwh from the grid it would still take 10 years to pay for the new panels not counting all the stuff I already have. I would like more power then I am getting but don't really wan't to pay for it.
    Thanks for the comments.
    gww

    Due to very short absorbs because of the opertunity load and me being there to watch input output and make adjustments, I only really don't lose most of my solars production except on those days I am not running night time loads to get the sgs back up. I pretty well try to ruin the battery for ten days then try to fix them give or take a bit..
  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: PV watts says

    Sorry sounds like you could use it!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Re: PV watts says
    gww1 wrote: »
    it would bring my cost down to $0.24 per kwh produced.
    gww1 wrote: »
    At $0.10 a kwh from the grid it would still take 10 years to pay for the new panels not counting all the stuff I already have. I would like more power then I am getting but don't really wan't to pay for it.
    Thanks for the comments.
    gww

    People have some funny ideas about RE payback. If the total lifecycle cost of RE generated power is more than the grid rate, it NEVER pays back. I guess thats just addiction at work ;)

    Since i did our basic install and costed it at 45c a kWh, weve since bought a second inverter, a replacement combiner, new sub disconnects, SPDs, WbJr, monitoring gear....

    None if it was *needed* you understand. And thats without even mentioning lusting over iron phosphate. Thatll really mess with your numbers.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: PV watts says
    zoneblue wrote: »
    People have some funny ideas about RE payback. If the total lifecycle cost of RE generated power is more than the grid rate, it NEVER pays back. I guess thats just addiction at work ;)

    If you are talking total cost for grid rather than rate, since many off gridder's would have to run a line at a very high rate.

    Also sorta doesn't work for me, while my cost is greater than the grid, I already had the battery, some equipment (all figured into my cost BTW) and had to move, would you buy a year old forklift battery? If I drop off the existing equipment I suspect I am well, below calculating out 30 years, about 27 cents a watt with out tax credits but with expenses)

    Solar panels will have some residual value to, I have a 30+ year old solar panel being used by a friend right now, It's not worth it's initial cost, @$1500 for a 55 watt panel if it was at the quoted average price Here. But it has some residual value, as does the lead in the lead acid batteries.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: PV watts says

    zoneblue
    People have some funny ideas about RE payback. If the total lifecycle cost of RE generated power is more than the grid rate, it NEVER pays back. I guess thats just addiction at work

    Here's the point, Unless I decide to not fix or replace things as they break the cost is there if I don't buy the panels or if I do. Sooo, The panels including racking, if they last for more then ten years and I have a place to use the power is cheaper then the grid. Nothing else that I have did to this point was but as I already have everything else 9 more panels is cheaper then the grid. Now saying that I still may not do it, cause doing it might be too smart and I am not sure I want to ruin my track record.

    I want to cause I think it is a smart move but I don't want to cause I can't seem to stop. Took one of my turbines down yesterday and put longer blades on it and put it back up today. I wan't to build a bigger one. These panels are a genious move compared to that. I still haven't insulated my house better.

    move along, move along.
    Cheers
    gww

    PS I planted 15 fruit trees that I won't spray or prune after the first year, feeding 60/70 chickens $90 a month for about seven eggs and I have only butchered 12, built bee hives so now need bees, geezzzz
  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: PV watts says

    Try being unemployed/semiretired, that will make you happy for what you have and less interested in expanding. I'm a good scrounger though and enjoy playing, I haven't put up the additional panels and it's my fall project, but haven't even played with the rack design yet. Don't think it will cost me much of anything additional, I have the CC, wiring, brackets and 90% of the frame material.

    "...there behind the glass is a real blade of grass"
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: PV watts says

    whitt
    I had to buy the lumber but I scrounged the tin to make sort of a shed of it. I had a hard time scrounging before I retired cause I was finishing up work a state away and could only work here two weeks every six months. I scrounged the chickens, somebody gave me 23 then someone else gave me the rooster and an incubator did the rest. I scrouged the bee hives, I made them from all kinds of savaged lumber. It is harder then using new. took a lot longer then I thought it would. I don't have much money but I am also a bit anti social. I find making things, looking for things that might work and sometimes using things that don't work well, better then going to the store. I am not sure my panels will last that long as I mounted them directly on 2x6 boards. I sometime break things while trying to fix them. Nothing is sacrid. Some time I even learn abit sometimes not. I do enjoy goofing off even if it isn't always productive.

    I always want to expand but find I am to cheep to do so. It is an accident that I have what I have. I built solar panels then saw a inverter and cc on craigs list. Then tried to get enough to fit the inverter. Then had to figure which wire to run long distance cause I didn't want a treeless yard. He probly doesn't remember but coot basically insinuated I was an idiot and doing it backwards. (you got to still love a guy when he is right all the time). I really started trying to build winturbines out of junk.

    I don't need solar and it doesn't make sence but its just like last year when propane went through the roof cause the one guy who has a corner on the market sent it all overseas (cause he didn't know it was going to be cold last winter). I used propane my whole life and never worried about the thermistate. I used baseboard heaters last winter. I just like the ideal if I want I can live without something. I don't expect to live without the grid but like to play in my mind that I could if I wanted. I may just goof off in a different way.

    Cheers
    gww
  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: PV watts says

    Sounds great! I need to get out and see your place sometime, If your passing through Columbia/Williamsburg area, drop me a note and I'll give you directions to my Tin Can. Sound a good bit like me. When doing my calculations there is a big factor I forgot to include, I have to harvest 2-3 cords of wood each years and I needed to put in a wood stove...lol.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Re: PV watts says

    When I talk about $$$/kWH pricing--I am not trying to turn the discussion into pure $ and cents pricing vs grid, etc...

    Trying to give the power a real value. Would a new low power laptop that uses 20 watts vs an old (near free) desk top computer at 250 Watts make sense?:

    20 watts * 10 hours per day * 365 days per year = 73,000 WH = 73 kWH per year
    250 Watts * 10 hours per day * 365 days per year = 912,500 WH = 913 kWH per year

    Assume 2 year life for laptop and $1,000 purchase price:

    $1,000 capital cost / (913 - 73) kWH per year = $1.19 per kWH "avoided cost"... (for one year of operation)

    If your off grid power costs $1-$2 per kWH, you could justify a new laptop almost every 2 years pretty easily over the desk top system.

    It helps with those pesky conservation questions...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: PV watts says

    Bill
    Good point.

    Whit
    My daughter went to mizzu. The guy who says he might sell me enough bees to get started lives close to columia, so maby next spring. My place is easy to find. I live in rosebud mo. It is just outside of the little town of about 400 poeple. If you go out hwy t I am 7/10th of mile and if you look up you can't miss the turbine. I am retired so anytime is a good bet that I will be home.
    Cheers
    gww
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: PV watts says

    My panels are 29.8 volts 7.88 amps in series of three.

    new panels below.


    Voltage Maximum Power 29.65
    Current Maximum Power 8.10
    Voltage Open Circuit 37.42
    Current Short Circuit 8.62
    Dimensions (inches) 65.67 x 39.37 x 1.57
    Weight (lbs) 44.1
    Tyco connectors
    Manufacture Warranty
    Power Output 10 years @ 90%, 25 years @ 80%
    Workmanship 5 years

    or

    Voltage Maximum Power 30.18
    Current Maximum Power 7.97
    Voltage Open Circuit 37.15
    Current Short Circuit 8.50
    Dimensions (inches) 64.5 x 38.66 x 1.42

    Weight (lbs) 40.79 lbs

    MC4 connectors
    Manufacture Warranty
    Power Output 10 years @ 90%, 25 years @ 80%
    Workmanship 5 years


    What would happen if I ran these in series of three and put on the same cc with my origional panels.
    Would it work with the other panels?
    Thanks
    gww
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: PV watts says

    What would happen if I ran these in series of three and put on the same cc with my origional panels.
    Would it work with the other panels?
    Thanks
    gww
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Re: PV watts says

    Those panels are close enough to idential Vmp/Imp ratings that you should be able to mix/match in any combination.

    If I had a choice, I would keep same panels grouped in strings, and add the new ones in parallel with the existing array (I like to keep current Imp in matched sets if possible--But should not really matter if you have some mixed old/new sets).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: PV watts says

    Thanks bill
    I know the 5% rule but also see where panels cancel other panels out, so basicaly I knew nothing. Now for my new search, What does poly or mlti cristal mean and what don't I want.
    $0.78 and $0.75 per watt not counting up to $300 shiping.
    gww
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Re: PV watts says

    Poly Crystalline is the typically cell that has that "shattered glass" or feathery crystalline look. The the big differences is that Poly panels are slightly less efficient at gathering sunlight and loss costly to make/buy.

    Mono Crystalline is a single/high purity crystal cut into cells and usually look pretty much like a black glass surface. Since Mono panels are slightly more efficient, they are slightly smaller than poly panels. And they cost more to make/buy.

    In general, for our uses--Get which ever one is cheapest $$$/Watt delivered to your door.

    Unless you are space constrained and more watts in the same area is worth the extra price to you.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: PV watts says

    BB

    Lots of space. Cheep fits my personality
    Thanks
    gww
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