New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance

Hello Folks,

Our household would like to "experiment" with solar electric power. And experiment more at a practical level rather than at a "kit" level. A challenge but not impossible.
We have a technical back ground with a lot of hands on experience, mixed with a bit of imagination, and a lot of will power.

We usually persevere through pure determination and thick headedness. We have read a lot and know enough to be dangerous but do not know enough, if anyone ever does.

We enjoy learning and dislike being "stupid or ignorant." We are always on a budget but have a disposable dollars to support our projects and adventures.
We enjoy a challenge and learning but dislike falling into expensive potholes that could have been avoided. We do not mind learning at the school of hard knocks and enjoy learning from experience.

We always like the "keep it simple stupid" approach. We do like to embrace bells and whistles but do not need the most technical equipment. There is a difference between "neat" and "over the top."

So we are interested in creating an off grid system with no intention of tying into the grid. We have no current load to run but I am sure we will be able to create one to meet our system capabilities as our system develops.

From the start, the system will certainly be used as a learning tool to teach our two young boys about a wide range of principles and concepts. What better way to actually learn about the principles of electricity.

Our thoughts include moving forward by constructing a system that would include;

• Four (4) Kyocera JD140 GX Panels wired together in either series or parallel depending on how far they will be installed from the controls.
• A Morningstar Tristar 45 amp Charge Controller
• A bank of DEKA gel batteries wired to meet the systems needs.
• A Samalex 1000 watt inverter or equivalent.

We would use the system to run a combination of small AC and DC loads including our ham radio, lighting for our boys tree house, maybe pumps for an aqua culture project, and whatever else we find we can connect. We of course would like to be able to use this system to operate if the grid goes down for an extended period of time.

We understand that due to our lack of known's and uncertainties it is difficult to create a system to work at peak efficiency. At the same time we want to select equipment that if things prove successful the system would provide for future expansion.

We are aware that we are approaching this project from different directions without a solid foundation. But we would certainly entertain any one's opinion on our plans and always enjoy working through constructive criticism when it is directed at the project at hand.

Thank you in advance for any thoughts any one might have to offer and keep up the great work. Sharing on knowledge on sites like this makes the world a better place.

Comments

  • solar_davesolar_dave Posts: 2,335Solar Expert ✭✭✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance

    Generally the most cost effective way in is a set of golf cart FLA batteries(X4=24 volt), some High voltage panels with a MPPT charge controller and your inverter. It is hard to recommend without knowing loads. Assume you want to expand start with a 24 Volt system, most people that start with a 12 V system unless it is very limited generally regret that decision.
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance

    Welcome to the forum.

    A couple of things right off the bat: how you wire the array will also dictate the charge controller used in respect to the system Voltage. The controller you list is a PWM type, which does not allow flexibility in this.

    Two good threads to start with:
    http://forum.solar-electric.com/showthread.php?15989-Battery-System-Voltages-and-equivalent-power
    http://forum.solar-electric.com/showthread.php?16241-Different-Panel-Configurations-on-an-MPPT-Controller

    Also, you do not want to use gel batteries; they aren't generally suited to RE systems.

    Based on the reverse engineering of picking panels first:

    Four 140 Watts panels = 560 Watt array.
    On a 12 Volt system using PWM controller (all panels wired in parellel) about 31 Amps peak current, enough for 300 to 600 Amp hours @ 12 Volt max. One set of GC2's as per solar_dave's recommendation would be fine for starting out (roughly 220 Amp hours @ 12 Volts).

    I also agree with him about doing 24 Volt system now; usually you'd only pick 12 Volt if there was a specific need for that system Voltage (i.e. mobile application).

    BTW, there are cheaper ways to get that much array if you use an MPPT type controller. At around 400+ Watts you are at the threshold where it starts to make sense to use the GT-type panels & MPPT controller.
  • PhotowhitPhotowhit Posts: 4,747Solar Expert ✭✭✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance

    It's generally a poor choice to setup a system and then see what it'll run...

    I personally would suggest, a tiny 12 volt system, perhaps just for your kids tree house. That way you can plan a system and show the boys how things work and why you need what you need. I think a very small system could provide some light and music and perhaps a small fan all on a 50 watt panel and a small sla battery and a charge controller. Running everything off 12 volt.

    This would give you experience from what, I and others, would consider a proper perspective. Known loads, and projected system capacity.

    I suspect if you've read you understand that this is NOT a cheaper way of having electric?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • SolarPoweredSolarPowered Posts: 626Solar Expert ✭✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance

    12volt systems drain batteries faster than larger voltage systems because voltage is limited so amps are increased and batteries are based on amp hours. No matter how you engineer a 12Volt system they will always be limited to a 2500~3000watt continuous draw for power, because bussing to conductor size will limit the power potential beyond 3000watts.
    Higher voltage systems cost more, but the return on investment is a healthier system and batteries.

    I only build 12V systems for portable systems, 24V and higher systems become to heavy for transporting.

    1000watts doesn't do much good. Peak surge will allow up to 15amps for start up for (X) amount of seconds its very limited, once inverter is drained of that surge continuous power from the AC end is roughly 8.25~8.5amp draw. Which means you will get 1 maybe 2 light bulbs, a TV, blender, and a 100watt stereo. To say the least its not much.

    An average 1000watts is typically consumed in an office space or live able space of a 100sq/ft room or equivalent.

    Kyoceras are not the best panels out on the market conversion efficiency from the different makes and models range from 13.5 to 15.5% conversion. There are many other panels in the solar market that are mono crystaline and conversion is in the higher 17%~20% conversion efficiency. More power for less real estate.
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance

    It is normal for polycrystaline panels to be 14 to 16 percent efficient; this has nothing to do with the Kyocera brand. They are fine.

    Power consumption is not a factor of square area of living space. Ever.

    24 Volt systems are more efficient due to lower current for the "same" amount of Watts: more power transferred as current means more power going to heat instead of work.

    Samlex has a 24 Volt version of their 1000 Watt inverter for a couple of dollars more. Note that these PST series inverters essentially have no surge capacity whatsoever. For <$400 you can get the 24 Volt 1kW SA series which has a surge rating of 2kW: http://www.solar-electric.com/sa1wa24vosiw.html These are still small capacity inverters and lack complex features and built-in AC chargers.
  • vtmapsvtmaps Posts: 3,738Solar Expert ✭✭✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance
    12 volt systems drain batteries faster than larger voltage systems because voltage is limited so amps are increased and batteries are based on amp hours.

    There are plenty of other reasons to choose one system voltage over another, but that is not one of them.

    Consider a system with four 220 ah 6 volt golf cart batteries. If you hook up all four batteries in series you have a 24 volt system. If you hook them up in series/parallel you have a 12 volt system. At either voltage the battery bank has 5280 watthours of storage. For any given wattage draw, the current through any battery in either system will be the same.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance
    vtmaps wrote: »
    There are plenty of other reasons to choose one system voltage over another, but that is not one of them.

    Consider a system with four 220 ah 6 volt golf cart batteries. If you hook up all four batteries in series you have a 24 volt system. If you hook them up in series/parallel you have a 12 volt system. At either voltage the battery bank has 5280 watthours of storage. For any given wattage draw, the current through any battery in either system will be the same.

    --vtMaps

    You mean the power drain will be the same, not the current.
    All else being equal this is true.
    But all else is not equal, and so the 24 Volt version would actually be drained slower due to less power loss to heat.
    Of course then you toss in the real world differences in inverters and the 12 Volt may use less than the 24: checking the two versions of the SA the 12V uses 17.16 Watts and the 24 uses 18 (both nominal). A trifling difference.
  • SolarPoweredSolarPowered Posts: 626Solar Expert ✭✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance
    It is normal for polycrystaline panels to be 14 to 16 percent efficient; this has nothing to do with the Kyocera brand. They are fine.

    Power consumption is not a factor of square area of living space. Ever.

    Monocrystsline pricing is inline with poly. Mono is higher conversion efficient, therefore better IMO. Poly does have some beneficial characteristics such as higher voltage output vs mono with higher amps, however if charging batteries it's best to have enough amperage to charge batteries Efficiently.

    I didn't say consumption, at all, I said conversion. Higher conversion efficient panels consume less real estate.

    Now energy consumption in relation sq/ft is in relation to California assembly bill (AB32) to reduce emissions to that of 1990 recorded levels. The measure of energy and its use per sq/ft whether it be kwh or BTU averaged in equall proportion to conservative energy demand. It's more of an energy audit equivelant. Not a standard, but a relevant correlation of how energy (kwh/btu) should be used in proportion to space (sq/ft).
  • vtmapsvtmaps Posts: 3,738Solar Expert ✭✭✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance
    You mean the power drain will be the same, not the current.

    No. I meant what I said. There will be double the current out of the battery bank in the 12 volt system, but since there are two parallel strings the current through any one battery in the bank will be the same as in the 24 volt bank.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance
    vtmaps wrote: »
    No. I meant what I said. There will be double the current out of the battery bank in the 12 volt system, but since there are two parallel strings the current through any one battery in the bank will be the same as in the 24 volt bank.

    --vtMaps

    In the context of efficiency the individual strings is not what matters. The 12 Volt bank could be made of single batteries of larger capacity, for example. The bank should be considered as a whole for this (not the same as determining construction of the battery bank and the considerations therein).
  • YehoshuaAgapaoYehoshuaAgapao Posts: 280Solar Expert ✭✭
    Re: New, Inexperienced, and an Expert - Looking for Opinions, Direction, and Guidance

    Keyocera 140 watt panels are 36 cells. You need a string of 5 for all-weather 48V compatibility. If your DEKA batteries are 12V and at least 130AH, get one more panel and you are good to go with a 48V system. I don't think Samalex makes 48V inverters though so you are probably stuck with 24V. With MPPT you can still put all four panels in series for 24V. If you DEKA batteries are 6V you still have one string. 12V you might have 2 battery strings. 5 140V panels are in the range of 3 60-cell (225-260W) panels so use the 3 total panel lines. 4 140V panels are like 2.25 60-cell panels so the 2 total panel line in the 24V section is the closest fit.



    Several pre-computed off-grid system designs (#PV,12/24/48V,#/type Batts,#BatStrings)

    Fuzzy starting point pseudo-kits.

    They are most helpful to people using the most common battery sizes (Group 31, Golf Cart GC2, L16), 150 volt MPPT charge controllers, and 60-cell PV panels. Group 31 and Golf Cart batteries have very good cost per KWh of storage. 60 cell panels are the most common, and 72 cell panels are also common. 60 and 72 cell panels are very economical. 72 cell panels don't fit xantrex controllers very well because they derate a lower voltage but they should fit other 150V MPPT controllers in strings of 3. 80 cell panels don't fit 150V MPPT well. 96 cell panels are a good fit for 150V MPPT controllers in strings of 2 but those can only be found on eBay or chinese trade sites but they do have good pricing. Panels below 60 cells do not have the cost efficiency.

    People using PWM controllers, extra high-voltage MPPT charge controllers (such as 250V Midnite Solar Classic 250 or 600V Xantrex MPPT 80), AC-coupled battery banks will not find these all that useful.

    If you have a different # of cells other than 60 you generally want to get 180 or 192 cells in a string for compatibility with a 48V battery bank in hot weather and 120V maximum controler voltage in cold weather (Xantrex derating voltage is 120V). 36 (strings of 5), 48 (strings of 4) and 96 (strings of 2) are scalable. 54 (string of 3) and 80 (string of 2) cell panels will have difficulty with a 48V battery bank in hot weather while putting out too much voltage with an extra panel in the string.

    People using recycled car/boat batteries that are not Group 31 or GC2, or are using industrial or forklift batteries will need to do battery bank sizing themselves, but the AH totals will still be there and helpful for comparing.
    • Using BB's formula: AH*AbsorbVolts*(1/0.77)*(1/#Hrs)=PVWatts
    • Formula transformed to: AH*AbsorbVolts*(1/0.77)/PVWatts=#Hrs
    • The 0.77 constant is from Solar panels usually delivering about 80% of STC plus 4% losses from the charge controller and wiring.
    • For simplicity, only using 60-cell PV panels, which tend to range fro 225W to 260 W with most being 235, 240, or 245W. 60-cell panels are the most common and are very economical.
    • For simplicity, only using MPPT charge controllers that are max 150 volts open-circuit (Midnite Solar and Xantrex have >150Voc charge controllers available).
    • For simplicity, only Group 31, GC2 Golf Cart, or L16 batteries are considered. Other common battery setups include Group 24, Group 27, Group 8D, Industrial batteries, and forklift batteries.
    • PV KWh/day is computed at 1000W STC = 5KWh/day - somewhat conservative, but assumes a full-sun day and no shading for at least 8 hours per day. My system in Arizona produces 6.25KWh/day per 1000W STC in a full sun day
    • BattKWh is for 100% DoD. Rule of thumb is to plan for 50% DOD. Different brands/kinds of batteries of different DOD peak total-KWh life. Surrette prefers 60-70% DOD. Trojan prefers 20-30% DOD.
    • PV KWh/day and PV charge rate ranges are 225W per panel at the minimum and 260W per panel at the maximum.
    • Systems with more than two PV strings require a combiner box with overcurrent protection on each string. For 60-cell panels in strings of 1, 2, or 3, Midnite Solar MPNV6 with a 15-amp breaker for each string will work good.
    • These designs do not favor high battery reserves (high reserve systems will have a lower PV to AH ratio and have slower charge rates) so most will require or really prefer the presence of a generator or a grid connection or both. PV panels are cheap and getting cheaper and are the longer lived components in the systems. Batteries are expensive and getting more expensive and are among the shorter lived components in the system.

    12 Volt Single Charge Controller Systems
    #PV     StrSize #PVStr  PV Watts    PV KWh/day  BatVolt #MPPT CC    Inverter (Min)      Batteries           #BatStr BattAH  BattKWh PV Charge Rate
    1       1       1       225-260     1.125-1.300 12      1 (20A)     300W Pure Sine      1x Group 31         1       130     1.56    9.35-10.81 hrs - Nominal
    2       1       2       450-520     2.250-2.600 12      1 (45A)     600W Pure Sine      2x Golf Cart GC2    1       225     2.7     8.09-9.35 hrs - Near Cost Effective Maximum
    2       1       2       450-520     2.250-2.600 12      1 (45A)     600W Pure Sine      2x Group 31         2       260     3.12    9.35-10.81 hrs - Nominal
    3       1 or 3  3 or 1  675-780     3.375-3.900 12      1 (60A)     1000W Pure Sine     2x L16              1       400     4.8     9.59-11.08 hrs - Nominal
    3       1 or 3  3 or 1  675-780     3.375-3.900 12      1 (60A)     1000W Pure Sine     4x Golf Cart GC2    2       450     5.4     10.79-12.47 hrs - Low-Nominal
    4       1 or 2  4 or 2  900-1040    4.500-5.200 12      1 (80A)     1000W Pure Sine     2x L16              1       400     4.8     8.09-9.35 hrs - Near Cost Effective Maximum
    4       1 or 2  4 or 2  900-1040    4.500-5.200 12      1 (80A)     1000W Pure Sine     4x Golf Cart GC2    2       450     5.4     8.09-9.35 hrs - Near Cost Effective Maximum
    

    24 Volt Single Charge Controller Systems
    #PV     StrSize #PVStr  PV Watts    PV KWh/day  BatVolt #MPPT CC    Inverter (Min)      Batteries           #BatStr BattAH  BattKWh PV Charge Rate
    2       2       1       450-520     2.250-2.600 24      1 (20A)     600W Pure Sine      2x Group 31         1       130     3.12    9.35-10.81 hrs - Nominal
    3       3       1       675-780     3.375-3.900 24      1 (30A)     1000W Pure Sine     4x Golf Cart GC2    1       225     5.4     10.79-12.47 hrs - Low-Nominal
    3       3       1       675-780     3.375-3.900 24      1 (30A)     1000W Pure Sine     4x Group 31         2       260     6.24    12.46-14.41 hrs - Low
    4       2       2       900-1040    4.500-5.200 24      1 (45A)     1000W Pure Sine     4x Golf Cart GC2    1       225     5.4     8.09-9.35 hrs - Near Cost Effective Maximum
    6       2 or 3  3 or 2  1350-1560   6.750-7.800 24      1 (60A)     Outback FX/VFX      4x L16              1       400     9.6     9.59-11.08 hrs - Nominal
    6       2 or 3  3 or 2  1350-1560   6.750-7.800 24      1 (60A)     Outback FX/VFX      8x Golf Cart GC2    2       450     10.8    10.79-12.47 hrs - Low-Nominal
    8       2       4       1800-2080   9.00-10.400 24      1 (80A)     Outback FX/VFX      4x L16              1       400     9.6     7.19-8.31 hrs - At Cost Effective Maximum
    8       2       4       1800-2080   9.00-10.400 24      1 (80A)     Outback FX/VFX      8x Golf Cart GC2    2       450     10.8    8.09-9.35 hrs - Near Cost Effective Maximum
    

    48 Volt Single Charge Controller Systems
    #PV     StrSize #PVStr  PV Watts    PV KWh/day  BatVolt #MPPT CC    Inverter (Min)      Batteries           #BatStr BattAH  BattKWh PV Charge Rate
    3       3       1       675-780     3.375-3.900 48      1 (15A)     1000W Pure Sine     4x Group 31         1       130     6.24    12.46-14.41 hrs - Low
    6       3       2       1350-1560   3.375-3.900 48      1 (30A)     Outback FX/VFX      8x Golf Cart GC2    1       225     10.8    10.79-12.47 hrs - Low-Nominal
    6       3       2       1350-1560   6.750-7.800 48      1 (30A)     Outback FX/VFX      8x Group 31         2       260     12.48   12.46-14.41 hrs - Low
    9       3       3       2025-2340   10.125-11.7 48      1 (45A)     Outback FX/VFX      8x Golf Cart GC2    1       225     10.8    7.19-8.31 hrs - At Cost Effective Maximum
    9       3       3       2025-2340   10.125-11.7 48      1 (45A)     Outback FX/VFX      8x Group 31         2       260     12.48   8.31-9.60 hrs - Near Cost Effective Maximum
    12      3       4       2700-3120   13.50-15.60 48      1 (60A)     Outback FX/VFX      8x L16              1       400     19.2    9.59-11.08 hrs - Nominal
    12      3       4       2700-3120   13.50-15.60 48      1 (60A)     Outback FX/VFX      16x Golf Cart GC2   2       450     21.6    10.79-12.47 hrs - Low-Nominal
    15      3       5       3375-3900   16.875-19.5 48      1 (80A)     Outback VFX         8x L16              1       400     19.2    7.67-8.87 hrs - At Cost Effective Maximum
    15      3       5       3375-3900   16.875-19.5 48      1 (80A)     Outback VFX         16x Golf Cart GC2   2       450     21.6    8.63-9.97 hrs - Near Cost Effective Maximum
    

    Large 48V multiple charge controller systems - These larger systems will be more likely to be grid-tied bi-modal systems (battery backup or mini-grid).
    #PV     StrSize #PVStr  PV Watts    PV KWh/day  BatVolt #MPPT CC    Inverter (Min)      Batteries           #BatStr BattAH  BattKWh PV Charge Rate
    24      3       8       5400-6240   27.00-31.20 48      2 (60A)     Outback Radian      16x L16             2       800     38.4    9.59-11.08 hrs - Nominal
                                                                        or Xantrex XW6048
    30      3       10      6750-7800   33.75-39.00 48      2 (80A)     Outback Radian      16x L16             2       800     38.4    7.67-8.87 hrs - At Cost Effective Maximum
    48      3       16      10800-12480 54.00-62.40 48      4 (60A)     2x Outback Radian   24x 2V L16          1       1200    57.6    7.19-8.31 hrs - At Cost Effective Maximum
                                                                        or 2x Xantrex XW6048
    60      3       20      13500-15600 67.50-78.00 48      4 (80A)     2x Outback Radian   24x 2V L16          1       1200    57.6    5.75-6.64 hrs - Grid-Tie Aggressive
    96      3       32      21600-24960 108.0-124.8 48      8 (60A)     3x Outback Radian   48x 2V L16          2       2400    115.2   7.19-8.31 hrs - At Cost Effective Maximum
                                                                        or 4x Xantrex XW6048
    120     3       40      27000-31200 135.0-156.0 48      8 (80A)     4x Outback Radian   48x 2V L16          2       2400    115.2   5.75-6.64 hrs - Grid-Tie Aggressive
    
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