Just got a great deal on a little system

Thick8Thick8 Posts: 47Registered Users ✭✭
Hi All,
First time posting.
I've been looking into solar for several years now. I just got my first "starter setup" and have a couple of questions.
First the stuff. Bought this system for $340 from a school that built it with grant money for educational purposes. The class ended and I bought the system.
Batteries: (4) 8D 1720 CCA deep cycle marine https://www.napaonline.com/en/p/NBE8276
Inverters: (3) a 5000w AIMS modified sine wave, a 2000w Power Bright, and a Sun Solar 1000w pure sine wave.

The PV array was wired at 36v (2x3). Should I keep it at that or just run all the panels in series? The controller is labled at 150v max. I have about a 40-50 foot run from the panels to where the controller/batteries will be located.

Right now the system will be running the garage but I plan on adding some more panels/batteries because I would like to add in some of the house to the system as well. The goal is to learn enough to go completely off-grid as some point.
Any words of wisdom would be appreciated as I don't want to screw this up.
Thanks
John





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Comments

  • BB.BB. Posts: 28,073Super Moderators, Administrators admin
    I have to go now--But first thing to do is get a Hydrometer and measure the State of Charge of the batteries (or at least, a good/accurate voltmeter that can read 12.xx volts) and take care of the batteries.

    Assuming flooded cell batteries, you need to recharge to full now. And either keep them on float charge (~1-2 amps float controller per 12 volt battery minimum). Or recharge them (roughly 12-24 hour cycle depending on Amp rating of AC battery charger and what type/brand/model of charger) to full charge. Then either recharge each battery every ~30 days, or float charge them on a "real" charger that has float mode (many chargers will overcharge the battery bank over 30 days with too high of float charge voltage).

    Once stable, then you can start figuring out what you want to do with the solar power system. 

    8D batteries are roughly 225+ AH @ 12 volts. This is a nice size battery bank that can drive some pretty good sized loads... However if you have only 6x50 Watt (300 Watt total) panels, that is only, at best, good for float charging the batteries. If you cycle them any amount, you will need a much larger solar array:
    • 4x 225 AH * 14.5 volts charging * 1/0.77 panel+controller drating * 0.01 rate of charge = 169 Watt array minimum Float
    • 4x 225 AH * 14.5 volts charging * 1/0.77 panel+controller drating * 0.05 rate of charge = 847 Watt array minimum (weekend cycling)
    • 4x 225 AH * 14.5 volts charging * 1/0.77 panel+controller drating * 0.10 rate of charge = 1,695 Watt array nominal (full time off grid)
    • 4x 225 AH * 14.5 volts charging * 1/0.77 panel+controller drating * 0,13 rate of charge = 2,203 Watt array "cost effective" maximum
    The above gives you an idea of what amount of solar (panels tilted to your latitude, full sun, no shading from chimney, vent pipes, overhead power lines, trees, buildings next door, etc.).

    And to give you an idea of what a weekend/emergency backup system could produce (fixed array facing south, Leesburg VA):

    http://www.solarelectricityhandbook.com/solar-irradiance.html

    Leesburg
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 51° angle from vertical:
    (For best year-round performance)

    JanFebMarAprMayJun
    3.03
     
    3.60
     
    4.26
     
    4.71
     
    4.78
     
    4.93
     
    JulAugSepOctNovDec
    4.97
     
    4.75
     
    4.65
     
    4.50
     
    3.23
     
    2.71
     
    Pick a Non-Winter month of February, 3.60 hours of sun per average day (break even power, may need a genset, use less power in bad weather):
    • 847 Watt array * 0.52 off grid battery based AC inverter system end to end Efficiency * 3.60 hours of sun per day = 1,586 Watt*Hours per day
    Want to run a 30 Watt laptop, that would be:
    • 1,586 WH per day / 30 Watts = 53 hours (i.e. one day of charging, ~2 days of operation)...
    Lots of details we can discuss--But that is how the math works...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    edited July 8 #3
    Only 52% efficiency. That’s quite a hit. 
    So I will better off getting some more panels sooner than later to be able to actually charge the batteries. can I mix and match panels? The ones I got are $250 each at Home Depot which is kind of steep.
    i did build a generator out of a 8hp engine and a 60a/12v alternator. I charged the bank for about 2 hours until the amp flow dropped to 12a (3a per battery). I have a hydrometer and refractor at work which I will bring home tomorrow. I will be swapping the alternator out for a 200a one I have, plus I have a 2 cylinder engine that I can use too in necessary. But my goal is to not have to use the generator at all except for extreme circumstances.
    Thanks for the link to the calculator. That will come in handy. I also plan on building a sun tracking system for the array. I have a few arduino boards and large servos that I can use.
  • EstragonEstragon Posts: 2,947Registered Users ✭✭✭✭✭
    I'd suggest charging the batteries individually. Some may need more charging than others.
    With a 5000w inverter included, and 36v panel wiring, it could be 4 x 12v batteries in parallel, or 2s2p for 24v. Either way, batteries may well be unbalanced.

    Mixing panels is possible, but paying $250 for a 50w panel to do so probably doesn't make sense.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • PhotowhitPhotowhit Posts: 4,742Solar Expert ✭✭✭✭
    First thing to do is look at the inverters and determine the DC voltage input. They could be 12, 24 or 48 volt...

    If they had the panels configure as 2 strings of 3 panels likely a 12 or 24 volt system. Still need to check before hasing out where to go.

    What are your plans for the system? I don't know which 'Leesburg' you live near, guessing by the figures VA? It's less than will run a household, and as a hobby system, you might want to just use what you have and cut your losses. The batteries are 125 lbs and likely worth $35-45 as scrap if you have a couple bad ones.

    Get an idea of their health, maybe load test them and check for a quick voltage drop. See what system voltage your inverters run at... 
    ...and make plans for what you want to do with the system.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    The batteries are less than a year old and have been maintained from what i've been told. They still have a year left on the warranty so that's a good thing. I'll charge them and bring the battery tester home from work tomorrow (I'm a truck mechanic).
    The inverters are all 12 volt input. The 5kW inverter I got for free (as a bonus) from a guy who's truck I installed an APU in.
    My plan is to use this sytem to power my garage. I have some power tools, CNC table, lights, a radio, and a compressor. I'm not out there very often; maybe a couple of times a week for a couple hours. I also want to use it for storm/wind/ice outages we have here in SC. We were without power for about 6 days last year and are well overdue for a big storm. I also want this to be my test bed for a whole house solar system.

  • BB.BB. Posts: 28,073Super Moderators, Administrators admin
    Yes. Virginia.

    Very roughly, I would suggest a maximum of 1,200 to 2 000 Watts for the inverter maximum with 12 volt battery bank. 1,200 Watts at 12 volt is over 100 amps of current. Requires very heavy cabling.

    For a 1 000 ah battery bank, at roughly 250 Watt inverter per 100 ah at 12 volt (flooded cell lead acid battery) or 2.5 kW AC insincere Max for your 4 batteries (more than that, the batteries will not reliably supply more power.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Posts: 4,742Solar Expert ✭✭✭✭
    The brand AIMS is not known here for reliability. and 5000 watts on 12 volt battery bank is very silly. Doubt you have ever dealt with cabling as heavy as you would need to run 5000 x 1.1 efficiency / 12 volts = 458 amps. 4/0 cable is good for about 260 amps...  In addition it's a modified sine wave so motors will run hotter and sensitive electronics might have problems, I wouldn't trust it with a CNC machine.

    If the 2000 watt is a true sine wave inverter, it would be about the same as having a 15 amp circuit, and should handle most things. You will still likely want 4/0 short cables to connect it to the battery bank. You may have issues with voltage drop with large loads shutting down the inverter. Hard to run large loads on a 12 volt inverter. In addition 4 batteries in parallel creates other problems in sharing the load evenly and charging evenly. If you intend to have and use a system based on the 4 batteries, we would normally suggest a 10% charge rate from the array. That would be a 1700 - 2000 watt array. 

    Considering this, a 30 amp charge controller will not be very helpful, So an addition 2 - 80 amp charge controllers might be suggested for a 12 volt system. Fortunately charge controller are based on output amperage, so instead of buying 2, you could buy 1 and move to a higher voltage system and apply the money saved toward a higher DC voltage Inverter.

    So have you even considered if you have a good exposure to the southern sky to install solar?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    Hi Photowhit.
    Cables aren’t an issue. I’ve already wired the batteries in parallel and have the 5000 and 2000 watt inverters hooked up using some 1/0 wire from work. It’ll start a 15 liter Cat so it should work for the inverters. I plan on running the lights, radio, and compressor with the 5000w. It was free so...
    I’ve insulated the building and will be regulating the temperature with an open loop geothermal cooler. The the fan and pump will be run from the 5000w as well once I get it built.
    My plan is to run the CNC and laptop on one of the PSW units and all of my battery chargers from the other. I also have a 750w UPS that I may hook into the 5000w which will give me another PSW source.
    like I said this is a test bed for all the crazy stuff I’ve been thinking up for very the years.
    my goal is to not have to buy anything until I go big. Off the grid big. I’ve been looking at those 14-15 kw systems for about 30k. Someday.
    I have a clear view of the southern sky all year long
  • EstragonEstragon Posts: 2,947Registered Users ✭✭✭✭✭
    Starting a 15L engine, and running something potentially for hours isn't the same thing. As a matter of interest, what size breaker do you have on the 1/0 wire from the 5kw inverter to the bank?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    So I really only have enough solar to keep the batteries topped off (float). If I use the system then I will need to run the generator to replentish the power I use. I can live with that for the now I guess. I don't want the batteries to start sulfating if the system sits Idle for a month.
    My original question, "Should I just hook the array in series" hasn't been answered. The panels max output would be 110 volts. The CC is rated for 150 volts. The array would be more efficient right?


  • PhotowhitPhotowhit Posts: 4,742Solar Expert ✭✭✭✭
    Thick8 said:
    Cables aren’t an issue. I’ve already wired the batteries in parallel and have the 5000 and 2000 watt inverters hooked up using some 1/0 wire from work. 
    Big issue! Really! if you could run 5000 watts at capacity, without the huge voltage drop, the 1/0 cable will become a heating element!

    Did you wire the batteries for even charging and loads? If not wired correctly they won't share loads and charging correctly. This site will talk about how to properly wire 4 batteries in parallel.
    http://www.smartgauge.co.uk/batt_con.html

    Thick8 said:
     with the 5000w. It was free so... 
    Be careful as to how much it will cost you! Could bring down your whole system. Do you know the constant load of the 5000 watt inverter when on? 

    Aims has made some bad choices, an inverter running 5000 watts from a 12 volt battery is one of them. If the 2000 watt will run everything you need, just use it you won't have the additional loses.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • EstragonEstragon Posts: 2,947Registered Users ✭✭✭✭✭
    > @Thick8 said:
    >
    > My original question, "Should I just hook the array in series" hasn't been answered. The panels max output would be 110 volts. The CC is rated for 150 volts. The array would be more efficient right?

    Max voltage with 6 in series may be more than 110v in cold temps, but should still be well under a max 150v controller limitation.

    6 in series allows for smaller wire, but is likely a bit less efficient because of losses in the mppt controller bucking from 110ish volts to 15ish charging. With big wire, a lower voltage string configuration would be a bit more efficient. The difference is really a rounding error though.

    So, what was the breaker size between the 5kw inverter and the 12v bank?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    Photowhit said:
    Thick8 said:
    Cables aren’t an issue. I’ve already wired the batteries in parallel and have the 5000 and 2000 watt inverters hooked up using some 1/0 wire from work. 
    Big issue! Really! if you could run 5000 watts at capacity, without the huge voltage drop, the 1/0 cable will become a heating element!

    Did you wire the batteries for even charging and loads? If not wired correctly they won't share loads and charging correctly. This site will talk about how to properly wire 4 batteries in parallel.
    http://www.smartgauge.co.uk/batt_con.html

    Thick8 said:
     with the 5000w. It was free so... 
    Be careful as to how much it will cost you! Could bring down your whole system. Do you know the constant load of the 5000 watt inverter when on? 

    Aims has made some bad choices, an inverter running 5000 watts from a 12 volt battery is one of them. If the 2000 watt will run everything you need, just use it you won't have the additional loses.

    I just wired it the way that made sense to me so thank you very much for that link. I will rewire it to match #4. Here's how I have it now. I have it set up on a rolling rack so the picture is representative of how it looks from the backside of the rack. I haven't hooked up the PV yet but the alternator is hooked up where the pv is shown.
    I was wrong about the cable, it's 4/0 gauge HD truck battery cable. about as thick as my thumb. I forget the the numbering is backwards for aught cable.
    Estragon,
    I will probably have a 40-50 ft run from the panels to the batteries. I may be able to shorten that some but heard that higher voltage is better for a long run. Would the benefit be less than the efficiency loss of a lower voltage (36v) run?
    Breaker? huh... JK I have some 400 amp mega fuses at work. I was going to wire one of those in.
  • EstragonEstragon Posts: 2,947Registered Users ✭✭✭✭✭
    Max ampacity (NEC) of 4/0 is ~230a. 5000w÷11v sag voltage = ~450a, so the 400a fuse might protect the inverter, but the wire is still small.

    40-50 ft from to panels isn't so bad. You'd have to try various combinations of voltage, current, and wire size with a voltage drop calculator, eg:
    https://www.calculator.net/voltage-drop-calculator.html

    You can get a sense of the order of magnitude difference in controller efficiency vs voltage from these charts:

    http://www.midnitesolar.com/pdfs/classicPowerChart.pdf

    It boils down to the incremental cost of upsizing wire vs a bit of controller efficiency, and possibly life expectancy (controller may run a bit cooler bucking from lower voltage).

    All IMHO and FWIW.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    edited July 10 #16
    Great calculator. Thanks. 
    The wife chimed in on panel placement. 75 ft. from panels to controller. Seems like 10 gauge wire is the way to go. I did a wide range of volt/amp combinations and it stayed well within the 3% rule. Then I can add panels to the array as I find them. I have 8 gauge available at the same cost so I might go with that.
    The controler docs says 95% efficiency @ 80% load. I’m in the process of watching some review videos of the controller to gain some ideas of its abilities. The literature is a little confusing in places.
    So I think I’m going to keep it at 36v/5.42a max with a voltage drop of about 1.5%.
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    I have another question regarding the 12v/160a homemade generator connection. I was wondering if I need to add 200 amp diodes in the controller wires so that when i fire it up I don't back feed into the controller? Is this even something I should be concerned about? I'd rather not have a switch to throw because invariably I will forget to disconnect the PV array before diconnecting the controller or just forget them both and blow the whole thing up.
  • BB.BB. Posts: 28,073Super Moderators, Administrators admin
    It depends... Adding diodes adds something like 0.6 to near 2.0 volts drop (depending on diode type and current ratings). So, battery voltage regulation becomes a bit of an issue (remote voltage sense is common for larger power systems--aka two voltage sensing wires are on the battery terminals, and the regulator automatically ups the output voltage of the alternator).

    However, for standard automotive systems--Remote sense is not a common option/configuration (the little I have seen).

    There are a lot of details that need to be worked out (powering the controller, can it start if there is ~0 volts on the charger output, etc.).

    In theory the standard rectifier bridge of the alternator should have relatively insignificant leakage current for your large battery bank. Probably just leave the genset switch "on" during the winter and only turn it off when you pickle the genset for storage during the sunny season.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    edited July 11 #19
    I guess the question I'm asking is; Do I need to be concerned about the controller when I'm running the generator? The Alternator has been thoroughly tested and functions properly. I don't think I should have an issue but want to make sure. 
  • mcgivormcgivor Posts: 2,314Solar Expert ✭✭✭✭✭
    The controller looks at the battery voltage responding when the voltage drops, if an alternate source is providing current at a voltage above that of which the controller is capable of supporting, it will see this as a parameter it can't compete against therefore backing off. The inherent design of the controller would not allow current to flow in the reverse direction, if this were the case what would happen overnight when there is no PV input? For this reason, it's my opinion that the addition of diodes between the battery and controller would be superfluous. Again just an opinion.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 

  • BB.BB. Posts: 28,073Super Moderators, Administrators admin
    If you are asking about the solar charge controller, then a properly operating alternator (or other charging current source) in parallel with the solar charge controller should not be a problem.

    Issues can include...
    • Use separate cable runs from each charging source to the battery bank (running both on one set of cables can cause excessive voltage drop, if you have a fuse/breaker and it trips from over current, alternators can easily supply 2-3x higher current on their output and if on the same cable/breaker as a solar charge controller will over voltage the output of the solar charge controller and probably fry the solar controller.
    • And if you have an "anternator disconnect"--Only turn it off when the alternator is not running. Flipping a switch/breaker when alternator (or any DC current source really) can cause an "inductive spike" which can damage attached equipment ("stopping current flow can cause any inductive load to generate a high voltage spike as the inductor field collapses).
    • And don't run the alternator without a load/battery bank attached (if you can help it)--It can easily generate 100 volts or more on its output.
    • Lead Acid battery banks can start getting "hot" when over C/8 (~12.5%) rate of charge, especially if state of charge is over >~80% (as lead acid batteries approach 100% state of charge, they became less efficient and generate more heat internally).
    • When equalizing a lead acid battery--Adjust the charging voltage so that EQ charging current is around 2.5 to 5.0% rate of charge--Higher rates of charge can quickly overheat the battery bank.
    • Do not "float charge" the battery bank at more than ~2% rate of charge (hours/days on end). Lead Acid batteries can overheat (as well as vent lots of gasses from "excessive EQ" current).
    Those are the basic warning I can think of... Most of them you would never do in real life--Just trying to make sure all the bases are covered.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    All very good advise. I hadn’t thought about the spike when turning off the field with the alternator running.
    The batteries I have are rated at 430 minute reserve capacity so the Ah rating is 716 for the bank, right? So a charge rate of 143a is 10% charge rate. If so that means my 60 amp alternator is pretty weak. I’ll have to get the 160a one on line.
    I charged up the bank with the 60a alternator. Over the time span of 2 hours the charge rate started at 58a and was at 28a when I shut it off. The bank’s open voltage was 12.6v when done.
    I found a couple more of the same type panels for $80 a piece so I plan on getting 2 more to max out the CC’s 30a rating. That will maintain about a 4% float right?
  • BB.BB. Posts: 28,073Super Moderators, Administrators admin
    The reserve capacity calculation is "different" than the 20 Hour Discharge Rate value that we usually use. Probably something like ~225 AH minimum per 12 volt battery.

    The reserved battery test is something like 25 amp discharge until dead (driving the car at night when the alternator failed).

    The 20 hour rate is how many amps can you draw for 20 hour from 100% full to 0% empty:
    • 225 AH battery / 20 hour discharge rate = 56.25 Amps (for that 20 hour period)
    4 of these batteries in parallel will give you a 12 volt battery bank with (4x 225 AH per battery) 1,000 AH @ 12 volt battery bank.

    Roughly a flooded cell lead acid battery is "Full" when the charging current falls to ~2% to 1% of the battery AH rated capacity when charged at the "correct" charging voltage (typically around 14.75 volts for FLA).

    Or if you hold 14.75 volts for 2-6 hours (absorb mode charging) the battery is full (~2 hours for partially discharged battery; ~6 hours of absorb for heavily discharged battery).

    A resting Fully Charged FLA battery is around 12.7 volts (measured after a few hours off of the charger--Resting Voltage).

    And you can confirm with a hydrometer to measure the specific gravity of the electrolyte (FLA battery only). Some additional reading:

    https://www.solar-electric.com/learning-center/batteries-and-charging/deep-cycle-battery-faq.html

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    Thank you for that.
    I ordered the 2 panels and the remote screen for my controller as it didn't come with it. With all the numbers you've been throwing around it made good sense to know what the controller is doing.

  • littleharbor2littleharbor2 Posts: 1,072Solar Expert ✭✭✭✭
    Pretty sure you need the remote meter to change charging parameters.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • BB.BB. Posts: 28,073Super Moderators, Administrators admin
    Myocardia (Robert) found a couple of my wording/math mistakes in the above post. They have been corrected. Teach me not to use a calculator for "2+2" problems...  :/

    Thank you Robert.
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    So the remote meter and 2 additional panels made it here. The panels are all mounted to a frame that I made from an easy-up frame who's cover fell apart from exposure. I used the stainless A&N bolts that held it together as well. So I'm only into the frame and support pole about $40. The pole was set in concrete this morning.
    I wired the panels in 2 clusters of 4. So the max output should be 75V/5.5A. This seemed like the best configuration to minimize voltage drop. I didn't bring home any wire from work so I won't be able to connect the panels to the CC till next week.
    I'll get some pictures tomorrow once it's hung.
  • BB.BB. Posts: 28,073Super Moderators, Administrators admin
    One warning about using stainless steel bolts and nuts. Depending on the grade of stainless and such, it does have a very good tendency to "galling" when when you run the nuts on the bolts for SS.

    Get some "anti-seize" compound (a grease with some sort of solid lubricant) to put on the bolt threads before running the nuts and tightening. Otherwise the two will seize together and you just have to twist them (and snap the hardware) to take them apart again.

    You can get the compound in tubes or cans from the local auto parts store.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    It's up. 79v/4.6a at 9am. So tempted to go buy wire at Lowe's.
  • BB.BB. Posts: 28,073Super Moderators, Administrators admin
    I cannot tell from the photo for sure--But it looks like you need some diagonal bracing somewhere in that rectangular mounting (triangle diagonal). The idea is that you want the framework to be stiff... You do not want to use the solar to be shear members (resisting parallel-gramming forces in the rectangular frame, or any twisting of the subframe either).

    Also, where the pipe attaches to the frame using a pair of u-bolts... Is there anything else to resist the array twisting at the joint (weldments or similar)?

    Diagonals from the outer framework down a couple of feet to the pipe to stabilize both the array and reduce bending forces on the pipe may be helpful too.

    It looks like your property may have quite a few trees as windbreaks---That is certainly helpful.

    -Bill "not an array mounting expert" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • littleharbor2littleharbor2 Posts: 1,072Solar Expert ✭✭✭✭
    BB. said:


    It looks like your property may have quite a few trees as windbreaks---That is certainly helpful.

    -Bill "not an array mounting expert" B.
    From the looks of that structure, it's going to need all the wind break it can get.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

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