Another Newbie

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  • PhotowhitPhotowhit Solar Expert Posts: 5,147 ✭✭✭✭
    Re: Another Newbie
    Dang, they are out of those panels until late November... Hmmm....

    Well since your using an MPPT charge controller you can use any panel and conver to your needed output, so see what people have.

    Our sponsor has some pretty good deals and is a reliable source;

    http://www.solar-electric.com/hiposopa.html

    Also your in California, so you might actually have a solar store near by, they would take the big shipping costs out. Not sure if solar is taxed in california, some states (Florida, I know) solar isn't taxed.

    You might be sure to buy in pairs, this might help in expanding your system.
    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
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie

    OK, I went with 4 230 watt panels... I think this will be a good start... At first, I thought 3 would be enough, but I decided on 4 instead... My original 400 watt system has more than doubled!
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie

    So, now I'm racking my brain on whether to go with 12 or 24 volt battery banks... All my 2 way radio gear is 12 volts, so going with 24 volts means I would either need that 24 to 12 volt auto xfmr, which is over 400 bucks, or a 120 volt to 12 volt power supply off an inverter, which just doesn't make sense to me... Hmmm...
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Another Newbie

    How much current do you need for your ham equipment?
    DC-to-DC converter (use of the term "autotransformer" in this context is incorrect) 20 Amp: http://www.solar-electric.com/12to24or24to.html Much less than $400. A 12 Amp is less than $60.

    You gotta shop around. :D
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie
    How much current do you need for your ham equipment?
    DC-to-DC converter (use of the term "autotransformer" in this context is incorrect) 20 Amp: http://www.solar-electric.com/12to24or24to.html Much less than $400. A 12 Amp is less than $60.

    You gotta shop around. :D

    Yea, I saw that one, as well... As far as ham gear, I have a 500 watt amplifier, that pulls up to 50 amps on peaks, and the radio that drives it probably pulls close to 15 amps... I see those "auto xfmrs" can be used to equalize a 24 volt bank, while puling off of 12 volts... That might be the ticket...
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie

    OK, back to my diary... Here's my latest thoughts, since I went with four 230 watt panels... Two strings of two 230 watt panels going down to a combiner/breaker panel... Suggestions? I guess I could run them all in parallel, but I'd like to cut wire size... As well, since I have a MPPT charge controller, I could run them all in series, but my concern would be losing the whole chain if a good sized bird were to land on one panel and cast a shadow on some cells... At least with two strings, if a bird took out one, I would still have one chain working...

    I'm feeling more and more like I want to go to a 24 volt battery bank, with four 220 AH 6 volt golf cart batteries in series... I'll just have to work out my 12 volt needs...
  • BB.BB. Super Moderators, Administrators Posts: 30,226 admin
    Re: Another Newbie

    Don't you need close to 13.8 volts or so for your Ham gear to transmit at rated power? I know there are some DC to DC converters that can boost "low" 12 VDC to ~14.0 volts--But that is even more gear/$$$ to look at.

    If so--I would seriously consider going with a nice 1,200 watt AC inverter instead. Less issues of routing heavy 12 VDC cable around to manage that current--Plus you will be pretty much at full power (assuming you have reasonable AC input options to your gear).

    On the other hand, inverters can be electrically noisy (but DC to DC converters are probably about the same). You could go with a good sized 12 VDC battery bank and just "charge" it from your 24 volt bank when needed (AC to DC battery charger, 24 to 12 volt down converter, or even an MPPT battery charger connected to the 24 volt bank as "solar input" and then to your 12 volt bank).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Another Newbie

    If these are the 230 Watt panels I'm thinking of they have a Vmp around 30 which means you must run two is series for a 24 Volt system otherwise there wouldn't be enough Voltage to charge. Running all four in series is not the best option as the controller's efficiency goes down the greater the difference between array and system Voltage. As a rule of thumb the nominal array Voltage should be no more than 2X the nominal system Voltage if possible. The higher Voltage will minimize problems with V-drop for a given wire size and distance. It is doubtful that a bird will perch on a panel, especially one large enough to block a cell segment and drop its production out.

    My feelings are that unless you are limited to 12 Volt for some reason (like RV or mobile applications where it is the standard) go with 24 Volts.
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie

    I like the idea of a 12 volt battery charging off the 24 volt bank... Actually, I have a 100 watt panel that I could use to charge my radio battery, as well... I never had any problem running my radio and amp off a blue top Optima that I kept charged by a cheap charger...
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie

    What is the most cost effective solution to combine, disconnect, and over current protect my two strings? I was thinking a good quality 2-pole fused AC disconnect with T fuses... While the Midnite combiner boxes look nice, the electrician in me knows there has to be a cheaper alternative...
  • BB.BB. Super Moderators, Administrators Posts: 30,226 admin
    Re: Another Newbie

    If you have just one or two series strings of solar panels, you don't need any fusing/beakers at all... For most panels, you only need a series fuse/breaker for 3 or more strings in parallel.

    And then for the solar panel disconnect--You really do not need one unless you have a reason to turn off the panel power to the charge controller for some reason during daylight hours. Then you can look for a DC rated switch (RV, Marine, Automotive, etc.) if you wish... You really do not need an over current protective device here.

    You will a breaker or fuse between the battery bank and the charge controller for safety (near the battery + terminal/+ bus bar connection typically). The is to protect against high battery current from frying the wiring back to the charge controller if there is a short somewhere in the system.

    These are nice stand alone breaker/switches--But not cheap.

    And "standard" DIN rail breakers for 1/4 the price above.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie
    BB. wrote: »
    You will a breaker or fuse between the battery bank and the charge controller for safety (near the battery + terminal/+ bus bar connection typically). The is to protect against high battery current from frying the wiring back to the charge controller if there is a short somewhere in the system.
    -Bill

    I'm guessing it would be wise to use a breaker between the batteries and inverter, as well... Cant hurt...
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Another Newbie

    just to throw another option into the mix here you have now doubled what you were going to buy in pv so your charging via solar will go twice as fast. you could put a good dc switch inline, like the blue seas, and bulk charge a separate battery bank for only your radios. after charged you can use a cheap pwm cc and your 100w pv to maintain the radio battery bank while the main pvs get switched back over to the main battery bank. that's one nice feature of mppt controllers is that it is not difficult to go from a 24v battery bank to a 12v battery bank and back again. some will do this automatically.

    separate battery banks insure one won't deplete the other. i use separate batteries for ham and home, but the 500w linear is quite an energy hog and won't even boost your signal 6db. you will have about 20a from the radio and another 50a from that amp for a 70a draw. you need a big battery bank for this and more solar to charge it.

    i find 100w on all bands to be quite good enough in most cases unless you operate the gentleman's band and they don't want to give you the time of day unless you run power. some on 80mtrs carry this attitude too unfortunately and won't talk to you even though they hear you fine.:grr this type isn't worth talking to in the long run anyway.
  • BB.BB. Super Moderators, Administrators Posts: 30,226 admin
    Re: Another Newbie

    Absolutely. ;)

    Even a single "car sized" battery can output hundreds of amps or more into a dead short.

    More or less, think of the battery as the "heart" of your system. And each circuit that hangs off of the battery / bus common connection can be evaluated separately from all the other circuits.

    Basically, wire a single or dual parallel strings of batteries to your +/- bus connection points. If you have three or more parallel strings of batteries, you should have a fuse (or breaker) per string rated for the interconnect wiring (say you have 175 amp rated wiring, you should use a 175 amp maximum fuse or breaker per string).

    Now--In reality, many people do not fuse/breaker each parallel battery string because it is expensive and takes a fair amount of room for the breakers/fuses. There are some very nice small T fuse holders that can bolt directly to a battery flag/terminal. Blue Sea has some single and dual T fuse holders:
    Attachment not found.
    For me, I have seen my fair share of automotive/truck fires from shorted battery leads and cannot imagine what a 1,000 AH 12-48 volt battery bank short would be like without a fuse/breaker or heavy bolt cutter nearby. :cry:

    Now you have your common bus +/- connections (and the - bus typically grounded to vehicle frame and/or earth ground/water lines as appropriate) and ready for connecting your loads and charging sources.

    In North America, you would measure/estimated the maximum sustained current, then multiply by 1.25 NEC safety factor, and size the wire/fuse/breaker to the next available size.

    Say you have a 1,200 watt inverter running at 12 volts... More or less, the calculations would be:
    • 1,200 Watt * 1/0.85 inverter eff * 1/10.5 volt batt cutoff * 1.25 NEC safety factor = 168 Amp Branch Circuit minimum

    So, you would round up to 175 Amp rated wiring and fuse/breaker (if you could only get a 200 amp breaker, then you would round up the wire size to carry 200 amps too).

    You would do this same calculation for each load/charging source. And you should install the fuse/breaker as close as practical to the Battery Bus Connections (in boats, I think they use "within 18 inches" as their standard.

    Is it "over kill"--Sort of... This is the "engineering" way of ensuring that if somebody ever "used" 1,200 watts from their inverter when the battery was drained + voltage drop from wiring--Then they would be reasonably sure that the inverter will still function to specifications.

    And, if there is a short circuit somewhere, then the 200 amp rated wire will not overheat and catch fire before the fuse/breaker opens.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie
    niel wrote: »
    i find 100w on all bands to be quite good enough in most cases unless you operate the gentleman's band and they don't want to give you the time of day unless you run power. some on 80mtrs carry this attitude too unfortunately and won't talk to you even though they hear you fine.:grr this type isn't worth talking to in the long run anyway.

    :) I agree, to a point... Remember that I'm not operating a "linear" on amplitude modulated CB, which would pull about 80 amps... I'm on SSB, so so my linear amplifier's peak current is around 50 amps, but the overall draw is not all that much... Plus, I operate in the "war zone", where that 6 dB gain comes in handy...
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie
    BB. wrote: »
    Absolutely. ;)

    Even a single "car sized" battery can output hundreds of amps or more into a dead short.

    More or less, think of the battery as the "heart" of your system. And each circuit that hangs off of the battery / bus common connection can be evaluated separately from all the other circuits.

    Basically, wire a single or dual parallel strings of batteries to your +/- bus connection points. If you have three or more parallel strings of batteries, you should have a fuse (or breaker) per string rated for the interconnect wiring (say you have 175 amp rated wiring, you should use a 175 amp maximum fuse or breaker per string).

    Now--In reality, many people do not fuse/breaker each parallel battery string because it is expensive and takes a fair amount of room for the breakers/fuses. There are some very nice small T fuse holders that can bolt directly to a battery flag/terminal. Blue Sea has some single and dual T fuse holders:
    Attachment not found.
    For me, I have seen my fair share of automotive/truck fires from shorted battery leads and cannot imagine what a 1,000 AH 12-48 volt battery bank short would be like without a fuse/breaker or heavy bolt cutter nearby. :cry:

    Now you have your common bus +/- connections (and the - bus typically grounded to vehicle frame and/or earth ground/water lines as appropriate) and ready for connecting your loads and charging sources.

    In North America, you would measure/estimated the maximum sustained current, then multiply by 1.25 NEC safety factor, and size the wire/fuse/breaker to the next available size.

    Say you have a 1,200 watt inverter running at 12 volts... More or less, the calculations would be:
    • 1,200 Watt * 1/0.85 inverter eff * 1/10.5 volt batt cutoff * 1.25 NEC safety factor = 168 Amp Branch Circuit minimum

    So, you would round up to 175 Amp rated wiring and fuse/breaker (if you could only get a 200 amp breaker, then you would round up the wire size to carry 200 amps too).

    You would do this same calculation for each load/charging source. And you should install the fuse/breaker as close as practical to the Battery Bus Connections (in boats, I think they use "within 18 inches" as their standard.

    Is it "over kill"--Sort of... This is the "engineering" way of ensuring that if somebody ever "used" 1,200 watts from their inverter when the battery was drained + voltage drop from wiring--Then they would be reasonably sure that the inverter will still function to specifications.

    And, if there is a short circuit somewhere, then the 200 amp rated wire will not overheat and catch fire before the fuse/breaker opens.

    -Bill

    Being an electrician, I've seen plenty of fires, including 500 watt outdoor lighting, so that's why I worry about these things... I really appreciate all the input, guys... I understand electricity pretty well, and am an electrician, so that certainly helps, but words of wisdom from the real word of solar is really helpful...
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie

    Things I'm dwelling on today:
    How to mount my 4 230 amp panels on my roof... I could use unistrut and get creative, or break down and go with a track system...
    Which 6 volt batteries... I need 4 @ around 200 Hrs or so... Locally, I can get a Trojan T-105 225 Ah for $160, Energizer 232 Ah for about $100, US Battery 208 Hr for $100 or even an Energizer 208 Ah for $82...
  • BB.BB. Super Moderators, Administrators Posts: 30,226 admin
    Re: Another Newbie

    Here is one example of using Gutter Clips turned sideways poster "Solar Guppy" usedto mount rails to roof (in Florida, and I believe he got an engineering signoff for wind loading).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Another Newbie
    :) I agree, to a point... Remember that I'm in operating a "linear" on amplitude modulated CB, which would pull about 80 amps... I'm on SSB, so so my linear amplifier's peak current is around 50 amps, but the overall draw is not all that much... Plus, I operate in the "war zone", where that 6 dB gain comes in handy...

    gee, i hope you meant to say you are not operating a linear on cb. i agree that the power draw won't be constantly high with ssb, but the average will still be significant.

    i can't say on your mounting selection as there are many options and this is a weak area for me.

    if i had to choose i'd go with the trojans, but with the low costs on the other ones any will be good to go with. some of the cheaper ones do require a higher charge voltage which under some circumstances could exceed the max input voltage to some electronics like inverters or ham radios.
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie
    niel wrote: »
    gee, i hope you meant to say you are not operating a linear on cb. i agree that the power draw won't be constantly high with ssb, but the average will still be significant.

    Oops! Not... Now, when I was a younger rebel, well, you know... ;) 40 and 80 meter "war zones" are my preferred hangout spots...
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Another Newbie

    If going with Uni-strut have a look at the S-5 system http://www.s-5.com/solar/index_2483.cfm#16 of grips, a bit higher priced but have a simplified built in grounding system, which is overlooked sometimes... you can get them without the 'standing ridge' clamps ...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie

    Hmm... I know AGM batteries are a bit less forgiving than regular flooded, but low maintenance would be nice, as I'm not always at the cabin... I see that our sponsor has Outback AGM EnergyCells far a decent Price... The Universal AGMs aren't too expensive, either...
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Another Newbie

    the universals don't have as long of a lifespan as concordes and i would also assume the outbacks to do well too.
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie

    OK, I have been acquiring all the goodies, and using my 100 watt setup already for two way radio... Another question is whether to ground the panels directly to the ground rod, or take the ground to the ground bus at the PV disconnect? Speaking of grounding, should I ground the battery bank negative lead?

    Thanks again
  • BB.BB. Super Moderators, Administrators Posts: 30,226 admin
    Re: Another Newbie

    Generally, it is a better idea to take the ground of the solar panel frames directly to earth ground (local ground rod, main ground rod, water pipe, etc...--Which ever is closer).

    Usually, you don't want to bring the panel frame ground to the battery bank (or into the home and battery bank) as this could bring the energy from a lightning strike into the home too.

    If you do not have a chance of lightning in your area--it probably does not matter.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • paulskirockspaulskirocks Solar Expert Posts: 84 ✭✭✭✭
    Re: Another Newbie
    BB. wrote: »
    Usually, you don't want to bring the panel frame ground to the battery bank (or into the home and battery bank) as this could bring the energy from a lightning strike into the home too.

    If you do not have a chance of lightning in your area--it probably does not matter.

    -Bill

    OK, but should the battery bank negative be grounded at all, and, if so, should it tie to the same ground rod that the panels are grounded with? In the AC world, we have to have all the grounds tied together, even if we have supplemental ground rods... I assume it all should go back to one ground source, whether via same ground rod, or cold water, which should be tied to the ground rod...
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Another Newbie
    OK, but should the battery bank negative be grounded at all, and, if so, should it tie to the same ground rod that the panels are grounded with? In the AC world, we have to have all the grounds tied together, even if we have supplemental ground rods... I assume it all should go back to one ground source, whether via same ground rod, or cold water, which should be tied to the ground rod...

    Normally the negative battery terminal is grounded to the electrical safety ground; the same as the AC ground. (If this is an MSW inverter there are other issues regarding grounding and neutral-ground bonding.)

    The panel frames/mounts are most likely to be energized by lightning/stray Voltage which is very high Voltage and you do not want to risk introducing this to the interior of the home or to the DC or AC power lines. Hence the desire to connect it externally to its own ground rod outside.

    The NEC does not necessarily agree with this approach.
  • BB.BB. Super Moderators, Administrators Posts: 30,226 admin
    Re: Another Newbie

    There are (at least) two reasons to ground a system...

    The basic one for NEC is that when you ground the "return lead" (white wire)--It no longer can get much above zero voltages--And therefore is unable to "short to ground" and does not need a breaker or fuse for safety (cost reduction/ease of installation).

    So--If there is a short anywhere in the system, the "hot" fuse/breaker will trip (or pair of breakers if 120/240 VAC split phase circuit running 240 VAC) everything is safe.

    If there is a "neutral/white" wire to ground short, nothing happens.

    And because all of the major metal components in the home are grounded (water pipes, gas lines, water heaters, metal appliances, etc.)--If there is a short from "Hot" to anything metal--That metal stays "near zero volts" and trips the breaker (i.e., you don't want a short to the metal sink to raise it to 120 VAC--and then grab a faucet with the other hand in the water--etc...). (note, many other countries do not supply a grounded neutral--they float there wiring--which has other advantages and disadvantages).

    The other major reason to ground a system is to dissipate static charges and direct lightning energy to "earth", rather than into the home and such.

    Static charge is not a usual problem unless you have your metal solar frames on a tall roof (ungrounded). And not everyone has lightning--But for those that do--dealing with lightning, solar panels, antenna, etc. do require thought on how best to do it (safely).

    Note, if you have a small DC or AC inverter power system--Generally most people will not bother grounding the DC return (or even the AC neutral--which is a big discussion too--especially if you have an MSW type inverter). A "floating" system is pretty safe in that a single "short" or somebody touching one of the power wires will usually not get a bad shock. However--If there is a short, and nobody notices, the system is now ground referenced (by accident) and it is possible for people to be shocked and/or other damage due to a "second short"...

    If you are doing HAM radio or other hobbies that have externally mounted antenna/lights/displays/etc... And they are not portable--You probably should run your AC grounds to the "main ground"... And run a second ground wire from your (typically) negative battery post/bus to the same AC main ground. This will prevent you getting a "bias" voltage between DC and AC/House ground. And if you have lightning in the area--connecting DC ground to the SAME AC ground rod can reduce the chances of induced voltages (if you have two ground rods 20 feet apart and a lightning strike near by--The two rods can be, temporarily, have 100's to 1,000's of volts difference between the two rods.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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