few questions about solar power....

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    The "optimum" solar only A/C system probably uses a "smart VFD" and "solar aware" controller+software.

    Basically, only "turn on" when there is enough solar energy (don't try to run if there is insufficient solar energy).

    Once the controller is awake, then decide if there is enough solar energy to run the fan and compressor. Figure out how much solar energy and start the VFD at a low frequency (both to "soft start" the motors, and to only run the motors at a speed to not exceed the solar array's power capacity. As more solar becomes available, then run the frequency to the motors to increase their RPM (as needed--only run at RPM needed for cooling demand at that moment in time).

    Note that (again guessing), the fan and compressor motors are "permanent magnet motors" and NOT Induction Motors...  PM motors are more efficient as the "rotors" are already magnetized, vs an induction motor that uses the rotating magnetic field (from the field coils) to induce (or induct) a current in the rotor--The induced current creates a magnetic field in the rotor which interacts with the rotating magnetic field from the field coils to "drag" the rotor and spin the motor shaft--This costs something like 10% or so of the power used by an induction motor.

    Also be aware that VFD usually are 3 phase (or more) output. A single phase magnetic field does not "rotate" unless you use (for example) a motor start/motor run capacitor and a second set of field coils to create a rotating field. A 3 phase motor on the other hand, natively has a rotating field and does not need/use capacitors (or other methods) to artificially create a rotating field. PM motors are generally(?) going to be poly phase motors.... A quick motor guide:

    https://www.machinedesign.com/motors-drives/article/21831709/whats-the-difference-between-ac-induction-permanent-magnet-and-servomotor-technologies

    Here is a very nice Danfoss DC powered (with internal VFD) refrigeration compressor (and presumably PM motor)--Note some of these are designed to run directly from solar arrays::

    https://www.danfoss.com/en-us/products/dcs/compressors/compressors-for-refrigeration/direct-current-compressors/#tab-overview

    Note too that a solar aware VFD basically has a MPPT DC front end to optimally deal with the solar array's electrical characteristics. The information from the MPPT front end of the VFD is used by the controller to optimally feed energy (voltage, current, frequency) to the motors.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • JRHill
    JRHill Registered Users Posts: 353 ✭✭✭
    Let's not get geopolitical on this thread. And let's not do ancestry. (I am Ukrainian, at least where the lines were drawn after who won what war...). Tick me off a bit. Watch "Fiddler on the roof" and I cry each time. And I'm not Jewish.

    Let's move on....
    Off Grid. Two systems: 1) 2925w panels, OB VFXR3648, FM80, FNDC, Victron BMV-712, Mate3s, 240 xformer, four SimpliPHI 3.8; 2) 780w, Morningstar 30a, Grundfos switch, controller and AC/DC pump, 8 T105. Honda EU7000is w/AGS. Champion 3100. HF 4550, Miller Bobcat.
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    oh sorry, not getting political i assure you, maybe i have a hyperactive brain, when im speaking or typing, my brain wants to blurt out 1000other things all at once, btw, we are now conneted :) you are Ukranian like Leonard Nimoy (Spok) and i, French Canadian like william Shatner (well you know i hope), so we are connected, small world.

    question about the solar AC.. without getting technical, if i simply leave thepower switch to ON, will the evaporator/fan kick on as soon as the panels are pumping enough power ???

    and the reason id like a stand alone AC, id like it to be powered 24/7 on solar power alone from all the juice i collect in my army of lifepo4 batteries.. (yes i am grinning right now)


    and im not sure why there would be a surge of any kind but i imagine this would be safe enough to use my pc and maybe even my fridge... albeit always empty... i have dreams dude BIG dreams :)
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    edited August 2 #125
    At best, you are subjecting your appliances to either brown out conditions (running a fridge at 1/2 voltage cause the motor to either stall and draw more current, or subjected to constant starting cycles, which are known to overheat the induction motors.
    Power utilities lost lots of claims for brown outs damaging appliances and loss of food, many decades ago before they killed ac mains instead of allowing brown outs.
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    sorry at this point and time im figuring out a way to duct tape onto the roof of an EV van and keep a small AC powered and a laptop for entertainment and to charge the ev itself, im thinking the roof has 8000 inches square.. 4x 550 watt solar panels mounted up there will give me 2000 watts plus, if the solar panels are genuine, all 4 panels will take 9.1 m square.. 8000 inches square is 5.6 m square. and no i dont know how to do the tiny 2 for square...  how is my logic so far ??? and im thinking best idea is to connect the solar panels to a separate battery bank to charge the EV that way, although i dont know how many watts are flowing per hour in "slow chaarge" mode, i think i saw somewhere 2.5 to 3.5 kw... 
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    Dongfeng EC36 it is a passenger van about the size of a RAM promaster with  300 km range
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    the AC is brandless and will consume an average of 550watts
    thinking i can drive 50 km to 100 km a night , park somewhere in the daytime, get some Z's and charge the ev battery whilst staying cool... 
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    Unfortunately, this forum software does not support math symbols... The classic text would be mm^2 ...

    Ideally, you would want to use the Van's 41.86 kWH battery for your solar and A/C needs... Could you do it with this van? You would need to work with the manufacturer to get the details correct....

    Could you get 300 km on this battery bank... I guess it is possible, but would not be surprised if you actually got 1/2 that or 150 kM per full charge. Say 50 km drive or 1/3 rd battery capacity:

    41.86 kWH / 3 (for 50 km conservative guess) = 14 kWH per 50 km drive (this is a more believable number for a van)

    14,000 WH per day * 1/0.77 solar panel derating * 1/2,200 Watts of panels = 8.3 hours of sun per day

    For the Philippines, average sun:

    For a solar array (2,200 Watts) mounted flat to roof, the above is the "average sun" by month... Nowhere near the 8.3 hours of sun per day needed for 50 km drive (using the mfg's mileage numbers, would be around 4.2 kWH per 50 km drive)....

    So, you would need 1-2 days of charging just for 50 km range. Not including A/C power... Is this going to work for you? (let alone figuring out the solar array to van battery connections/controller/software/etc...).

    -Bill (purely guessing here) B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    edited August 6 #130
    oh wow, thank you for being so detailed, the vehicle is a chinese cargovan called dongfeng ec36
    but heres my interresing question, in order not to damage the ev' battery pack i was thinking of connecting the solar panels to a sort of umm solar battery pack ,i believe they all have a built in inverter, sorry my question at 220V plugged into a regular ourlet.. how many watts are goig from outlet to ev input ??? 3.5 kw per hour  ?

    https://images.app.goo.gl/YDQx2VFutyJgRfNdA
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    Don't know anything about the details of this van... The sales glossy states:

    https://dongfengev.com.ph/electric-vehicles/ec36/


    And you can look up the CCS2 charging port (and various others depending on where you live):

    https://insideevs.com/news/488143/ccs-combo-charging-standard-map-ccs1-ccs2/

    In any case, you would need to do a deep dive into the CCS2 specifications and the vehicle charging system to see what you can do... But if "plug in", you are probably looking at 1,000 Watt minimum from AC power.

    And finding an off the shelf 335 VDC LiFePO4 solar charger is probably going to be search thru EV after market vendors.

    Ideally, you probably would want to be within 20% to 80% or 90% of battery state of charge for longest battery cycle life.

    And you should look at the cost to replace a battery bank if/when it wears out or fails (or you mess up on your solar/custom charging system).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    agreed however, knowing myself, i think i should let a proffesional handle the installation, i dont think its a good idea to be inside a steel or aluminium box connecting things in 30C or more , not sure if i had a heat stroke here yet or not, but being a proud member of CAF i tend to push myself to walk that extra kilometer when i know i shouldnt, im sure you get me, question though, is my idea of a battery bank in between the ev battery ideal or should i hook up the solar panels straight to the EV battery ? using some sort of `18v to 21v solar charge controller to go dirrectly to the ev battery ? im sorry im unaware if it is wise to charge lifepo4 batteries whilst discharging them, seems to me. SLA batteries in a car does that all the time, or am i wrong ?

    hope those cool  hill roads in San Franciso are still fun to drive, i remember the curvy one going downhill with pretty flowers on both sides as a kid.. good times
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭

    is my idea completely crazy or completely mad ?

    i will only use solar power for charging the vehicle, the 550 w ac unit.. and maybe my msi laptop that gives me an orgasm just holding it :/

  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    im including as many details as possible for anyone to tell me if anything about this fantasy is a "no no" for example having the separate battery pack powering the charging the ev part and my funny looking AC unit
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    edited August 8 #135
    If you have the time and the money to pay some knowledgeable person to do the "conversion", it could be done.
    If you can't afford to walk away from $x,xxx if the conversion dies, I would suggest waiting until you can find a successful conversion with lots of time and miles on somebody else's money first.
    In engineering terms, almost anything can be done. Will it make sense to the owner, only the owner can make those determinations.
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • JRHill
    JRHill Registered Users Posts: 353 ✭✭✭
    @corporal_Canada : What is the cost of electricity where you live?

    Where I live in WA State:
    Basic Fee:                                     $ 23.83
    All Kilowatt hours @                    $ 0.1011
    Avg Residential Bill (1500kWh)   $ 175.48

    I have no access to grid power so choosing solar was mandatory for our household. But with the equipment related to solar plus three replacement battery banks (the last was LFP04) I'm just about to hit break even at 13 years into the project. There are/were no labor or professional costs - it's all materials. We don't have a monthly bill B) . Instead, including the original install, the expenses come as big hits and are for 99% of them, predictable. And the costs don't include generators and fuel which we use daily for 3 months in the winter to charge the batteries. I have made a few mistakes over the years which cost me money and for my sanity I don't track those $.

    One thing is for sure: if we had access to grid power we would be connected. I probably would still have installed solar and added a backup generator for security of perishables; I'm not sure if I would've added batteries. Our PUD only banks excess generation contributed against power used at the meter. I believe the bank balance is 'zeroed' on an annual basis but I'm not sure of the details as the policy is not documented publicly.

    This is obvious to me: we haven't lost power in all these years unless it was planned. Another thing is for sure: we would live differently than we do now. We are in peak power usage of the year right now and we use around 350kWh per month, not 1500. We have a microwave but no airfryer, electric coffee maker, space heaters, air conditioners and I don't leave and diesel equipment block heaters plugged into an outlet in the winter. I get ripped if I leave a single LED on in the shop and go shut it off so I have peace.

    Solar is a wonderful thing when the only other is nothing or a generator running most of the time. There are pain points in any direction. So I watch this thread with interest. Your power must be really expensive.
    Off Grid. Two systems: 1) 2925w panels, OB VFXR3648, FM80, FNDC, Victron BMV-712, Mate3s, 240 xformer, four SimpliPHI 3.8; 2) 780w, Morningstar 30a, Grundfos switch, controller and AC/DC pump, 8 T105. Honda EU7000is w/AGS. Champion 3100. HF 4550, Miller Bobcat.
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    in this city, which is powered using Leyeco i believe it is roughly 10.5 php per kw which isnt entirely polluting there is a geothermal plant producing 232.5 megawatt which is perfect, i heard all those that live next to it have free power... 

    please answer straight forward, which is better. solar panels to something that converts that voltage to battery pack voltage and then straight to ev battery ? or my idea.. solar panels to separate battery pack.. and plug THAT battery pack to EV charging port ? ive noticed quite a few chinese ev's with a built in solar panel, even one in your country.. the umm aptera ?

    which is better please
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    If you can wire up your panel(s) to the vehicle battery pack with the appropriate charge controller--That is the most efficient and least number of things that can fail.

    Otherwise, you can have a second pure solar power system (panel=>controller=>battery bank=> AC inverter=>AC charger=>vehhcle battery bank) would probably be an "easier" solution using "off the shelf" pants. Plus you can also use the solar power system + AC inverter + any DC loads and not affect your vehicle battery bank state of charge.

    Of course, this costs you the money, weight, and space for the extra battery bank, charge controller, AC inverter, etc.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    thank you, so i shhoud just make sure that the EV has a ac outlet to power my ac unit
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    Well.... There can be another solution. Some (few, many?} AC powered equipment can take (roughly) up to 380 VDC. This is the peak to peak voltage of a 240 VAC sine wave form.

    Most modern AC (and computer, etc.) systems that used AC input and DC output (VFD, and other non-induction motor systems. This is a very common capability of "power factor corrected" power supplies (an whole other detailed history of how/why this was done.

    In fact, this "native capability" has been leveraged (or at least suggested to be leveraged) DC power systems for data centers:

    https://www.datacenterknowledge.com/energy-power-supply/380v-dc-power-shaping-the-future-of-data-center-energy-efficiency

    So, it is possible that you could find/purchase DC powered A/C systems that could take your EV van's high voltage battery bus power directly.

    Now--This is a very complex subject--Need to verify the DC capability of an A/C system (or a computer, etc.). Also, there are lots of safety issues with running a high voltage DC power connection (fire, shock, etc.). And would also need to understand how the battery bank system "protects itself" against taking the battery bank to "dead" and destroying the bank.

    Not suggesting that this is a "good" solution for your needs--More or less, just showing you that, with engineering knowledge, Conceivably, there are off the shelf modern electronic A/C products that could take something like 134 VDC to 380 VDC without modifications.

    In the case of your exact question--You could only have a 230 VAC output from a DC to AC Inverter... And that AC inverter would need to be capable of taking energy from your high voltage DC battery pack (not necessarily a common off the shelf product).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    \ok, i am not ashamed to admit that i understood none of that
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    Basically, many AC systems that use some sort of AC input power supply (computers, permanent magnet motors such as those in electric cars, machining centers, etc.)--This are commonly called "inverter" based A/C systems

    Some of these 230 VAC (120-240 VAC) power supplies basically turn the AC input (say 240 VAC) into 380 VDC internally--Then use that high voltage DC to down converter into whatever power is needed by the device (A/C mini-split, computer electronics, etc.).

    Instead of feeding 240 VAC into the power supply and the power supply (internally) converts to 380 VDC--Instead, just feed 380 VDC directly into the power supply and skip the 240 VAC completely.

    I am not saying that you can do this (without a lot more knowledge and money)--But for a large company, this could be done. This how they can used a 380 VDC battery/power system and skip the whole AC to DC conversion that occurs inside the power supply.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    please educate me, what do i use to convert solar panel 18-21 volts to the voltage of the ev battery ??? dont think ill be able to link all the solar panels in series to match whatever the 42kwh van voltage is using
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    I really do not have any easy answers... For example, here is a company that says they are making "the first" Solar DC to EV plug controller... Due "soon" with a deposit for early shipment. This is for a larger solar array (300-600 VDC or so) and will cost nearly $2,500 (+/-???).

    https://enteligent.com/products/enteligent™-tlcev-t1-trusted-charging-presale

    Here is a white paper talking about a solar DC to EV system (not sure if looking for inverters, or a college project or what):

    https://www.nature.com/articles/s41598-024-69254-1

    It is not easy to follow, but does give an idea of what the complexity could be.

    Otherwise, your two basic options are to 1) contact the vehicle mfg. and see if they have a solar charging option, or 2) the "typical" method is to build a solar->battery-bank to store the energy and then use a DC to AC inverter to convert to 120 or 230 VAC, and then charge the vehicle with a compatible AC charger... Here is one company that does this with a portable system:

    https://blog.ecoflow.com/us/guide-to-electric-vehicle-solar-panel-charging/

    This is not cheap.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    yup, might have to put my solar charged EV van fantasy on pause, although i did see a 3 wheel ev today with a built in solar panel on the roof.. only 2000 of your dollars, might be handy for city driving, i usually stay indoors and for that time.. i could just let the solar panel charge the EV... think of it as a golf cart, they do have a 4 wheel version but 2000 , no solar panel included, if i ever figure out a quick way to transfer files between my phone and this awesome pc ill share the photo, and yes it is very chinese

    oh.. 60 kph max and around 80 km range on a full charge.
  • JRHill
    JRHill Registered Users Posts: 353 ✭✭✭
    What do the other forums you ask questions say about this idea?
    Off Grid. Two systems: 1) 2925w panels, OB VFXR3648, FM80, FNDC, Victron BMV-712, Mate3s, 240 xformer, four SimpliPHI 3.8; 2) 780w, Morningstar 30a, Grundfos switch, controller and AC/DC pump, 8 T105. Honda EU7000is w/AGS. Champion 3100. HF 4550, Miller Bobcat.
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭




    voila the 3 wheen and 4 wheel version of this cute golf cart.. apperantly the solar panel mounted on the roof of the 3 wheen is 200 watts,


    as for the solar charging the EV van.. reddit says CANNOT be done, laws of physics and all

    however if lets say any ev is 48v.. for EXAMPLE.. cant i link 4 solar panels in series ???
    wouldnt that produce the correct current to connect to the ev van battery directly ??? 

    PS.. if i purchase another 12v 60ah battery for THAT ev golf cart in that photo.. can i parallel link the 2 batteries and double the range ????
    would that damage the charger ?

    i imagine ill have to move power draw and power input from 1 positive to another

    otherwise.. ill go from 60km range to 120 km range, wouild be cool :)

    just need side curtains to keep out the rain 
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    and as an added bonus, i dont need a drivers liscense which is perfect cuz mine expired years ago  :open_mouth:
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    worth mentioning that apperantly the current owner of apple , mr Wozniak has Polish and Ukranian heritage in him, cool huh ?
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    edited September 6 #150
    kinda wondering as well, can i not opt out of the 200 watt solar panel and use a bigger 500 watt panel ? theoretically if the motor only uses 350 watts (will confirm now) means i should drive infinitely without charging, of course it doesnt always produce 500 watts, but theres a battery for that and yes im aware the solar panel will be gigantic, ill just have to find a way to macgiver it on there with duct tape and tie wraps.  still.. it would allow me to go on a 650km journey sans issues in theory... maybe an additional 12v 60ah battery parallel linked to the main battery might even help. or possibly add range... 

    i know this compoletely goes against the laws of motion and etc, however, newton was around, quite some time ago... things have changed
  • corporal_Canada
    corporal_Canada Registered Users Posts: 97 ✭✭
    in regards to your dc to dc thing, i kind of think my best bet is to just get the 4 solar panels and a battery pack (solar generator as it is sometimes called) furthermore, that is just a fantasy for now,, so you can shift any of your concentration off that ev van with solar panels idea towards something more tangible, like that photo of the golfcart above... 

    i simply would like to know if i can parallel link additional batteries to the main battery of the golf cart, even if the brand and AH arent identical,  to add 60 km of range, voltage is crucial, that i know,  and my 2nd question, lets say i find a slightly cheaper golfcart because maybe it doesnt come pre-equipped with the solar panel, can i not simply link a solar panel to that similarly as i would to a home based solar setup ??? solar panels to a charge controller and that directly to the battery terminals ? or should i be going through the golf carts built in charge controller ? i mean i understand that you cannot and should not dual charge any battery from 2 sources, so to avoid damaging the battery i should go through that ? you know in case i stop at a charging station, technically the solar panel will be exposed to sunlight as i plug in the golf cart to a land power source...

    i hope im getting my concern across to you, because i do know you are smart but me eing a Frenchie, the words i want arent exactly flowing into my little brain :/

    cheers