Mismatched Solar Panels – What happens? 200W 24V with a 50W 12V


If you have very different solar panels, with both different volts and different amps, is it worth it to use them together through one MPPT charge controller? We take two solar panels, a 24V 200W panel and a 12V 50W panel, and wire them in parallel and in series into an MPPT charge controller to a deep cycle battery. We measured the results to determine if it is worth the effort of adding the small solar panel to your DIY solar system.


34 replies
  1. Uad Incorporated
    Uad Incorporated says:

    Wish I could show picts.. it's a mess.. but functional.. 8 months so far. Could be better.. so.. q? For no money how can I improve my system from parts in the yard.. imaginingg i have multiple halves of everything( 1/2acre assorted "junk" collected for reuse) to pull stuff from microwave to tv to cars to .. treadmills to 12v this snd that.. etc😁😎

  2. Uad Incorporated
    Uad Incorporated says:

    That's nice.. 1/4describes me.. I have a few questions. PS I'm a residential and commercial electrician 20+ years and computerized machine technician..1989grad( hardware tech) which means squat…with solar. So basically I'm in school. ( For all those solar )wind power newbies… who wonder… ..yeah it's tough for me…hope that makes you feel better. I have 12 used pv panels from 1980's- 2000.. all 12v.. ( none put out 12v ) range is 16.8 to 18.8 one puts out 19.8(newest at 8.86amps) all the rest are just under 6 amps each..and a harbor freight 100w (4x25wpanels) amorphous kit(149$ on sale with 2 12led lights "free". The charge controler is 10 amp in ONLY. ..i have 80amps current from panels. I use polarity corrent 12gauge 2pron extension cords 6-16ft( you buy white) which ate 3-5$.each. so i went to their store and bought 20 for 10$.. a couple are 14 gauge. 12 gauge stranded can carry 22amos safely.. i 6 of oldest panels tied to 24 ft of courd from roof to 6 gang ppl lug.. yes .. your right that 10 plus ammos over cord capacity. I have line losses due to heat and length. Voltage drop Is negligible ..1v.. I basically run nothing thru the charge controller. It's output Is also plugged into 6 gang so i can monitor voltage of batteries… as well as 3 more cords 3p and 3p from roof.. only 11-2pm do cords heat at all from current.. yes it's technically not safe..lol. Neither I driving a car or riding a bike or being on the roif in AZ during mins season.. i worry more sbout falling off homemade ladder (weighing 450lbs)( the ladder i Wei 175). I play lotto.too.. better chance getting hit by lighting twice in a row than winnkng lotto.. call me crazy.. i accept. Necessity I the mither of invention.. poverty is the father of what??? So I made my own windmills out of junk in the yard im waiting on SSDI to approve me . Panels host 13-16 dollars each.. big one was 10$.. shattered glass… Works best of all the panels. So.. I run my dc ov power direct yo batteries. Because my 100 amp 23$ mppt charge controler ..nwas delivered… But I never got it..( mailbox thieves) so am going to buh another.. someday. All panels run parallel.. I've got junk car batteries i refurbished. 2@ 8/9 v in series making a 16.5 volt battery 2@7/8v making a 15v battery and 3 12v in parallel all tied parralel.. giving me a "5" battery bank.. 5 are eosom satlt batteries 2 are acid. All were junk .. one i paid 6$ for 16$ in Epsom salts.. basically I'm trying to have a 2000w to 2500w system. For under 500$. …… So for all those view out thrre snd me.. what do you think.. is 18v + you into my batteries direct super bad? When it get to 14v + I plug in ..turn on inverters and use to run my freezer . 12 v swamp coller i built direct etc. Why is direct charging bad.. not that i have much choice.. im going to build s few things I buy .. for 10x the cost… Anyway hope that and your answer helps folks. .. I am the regulator 10am to 5 pm..lol.

  3. Little D’s Greenery
    Little D’s Greenery says:

    Hi there I have 4 100 watt solar panels and 3 30 watt solar panels wired in to a Renogy mppt charge controller I am only getting 9 amps 15volts and 120 watts total output how do I fix my system to get the most out of it ? Take out the little panels ?

  4. ben grobben
    ben grobben says:

    nice video. is it possible to take 2 of the same panels and wire then in parallel. but 1 is in the shadow and the other is not. does it hurt the pannel that is in the sun? or does it not matter. thanks 🙂

  5. Ray okeedoki
    Ray okeedoki says:

    I have a damaged panel in shipping, that got replaced by the seller. So now I have two instead of one. As it still puts out power even though it is shattered glass on top. I bought it in pairs. And I have another pair I bought. All of them are 250W, so 2 pairs and a damaged one. I have worked out that the size of wire is crazy to have it as 12V, and that wiring the 12V panels in series pairs would give me 24v and half the current, meaning my wires could be half the thickness. As I was wiring for expansion. But I also have a brand new 12V 100W panel I bought over a year ago, that I have not used yet. And I am thinking of if I go 24V, as still in making bracket stage getting ready to go on the roof… will connecting a 250W and 100W in series, be a big problem? Considering the damaged one might not put out the full current, perhaps they may be almost evenly matched. Though I don't know what will happen when it gets wet with rain. Maybe some cling wrap on top might be a an idea? LOL??? I just don't like to throw things out… and where this is situated, no one can see the panels. As there is a house in the way of getting to see them. Being in the bush, its not an issue. I figure as with series that it will drop back to the 100W current, which is rated about 6.66A, oh watt a number lol. Kirchoff's law and all about series circuits and current being the same in a series circuit. With the busted one all marked up… hey is that the mark of the bust? mmmm

  6. Rizgar J
    Rizgar J says:

    If you have 400ah battery total with two inverter and 1000 watt as a load for each them one them run on 12v with 400ah and the other one runs on 24v with 200ah which one will last longer?







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  7. Brian D
    Brian D says:

    thats awesome, i actually just you tubed if i could join mine, I have a 24 volt 200 watt panel and a 12 volt 120 watt panel and I want to run them in series. So thank you

  8. Four ZeroFour
    Four ZeroFour says:

    Assuming someone just wired two panels with dissimilar VoC / VmP's in parallel, and left them in the sun… (not necessarily attached to a controller, or anything for that matter), would this result in 'backfeed' into the lower voltage panel?
    Would this damage the smaller panel? Or the larger one?

    Thanks for any input!

    ADRIAN OANA says:

    Ok, but how are you charging a battery of 12v, when the voltage has to be higher than 13v, to charge the battery. the problem is that your solar panel is giving you only 12v. so?

  10. Adil Panhwar
    Adil Panhwar says:

    hii how are you getting nice watts from a 200w 24v output 6.22A? i have installed 800w 12v pv with 50Amps pwm charge controller hardly i get 44amps into battry around 480watts which is just 60% of my solar system

  11. Ken The Solar Guy
    Ken The Solar Guy says:

    Thanks Amy. I always like watching your videos. I intended on stopping in to say hi this past winter when I was in the area but got tied up……check out the grid tied 15.2 kW system I installed in Branson Mo. at "Ken The Solar Guy", and let me know whatcha think!

  12. J & B Homeliving
    J & B Homeliving says:

    Thank you for the video.
    I still got a question.

    If you put a low amperage panel with an high amperage panel in series, does this mean that you push more amps through the lower amperage panel and that low amperage panel will heat up even more?


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