Mismatched Solar Panels- Same amps, different volts and watts 

Thanks, glad you are enjoying. Let us know if you have any requests.

Thanks Chris, your comments are unparalleled.

Touche! haaha!

By putting the 2 strings in parallel, you will minimize the losses, as the additional current from the 315s can go around the 290s. The MPPT charge controller will have trouble finding the optimal max power with the two different types going in. You won't get best performance, but it will work.

Thanks for your help

Because the current travels in a loop, it would hit the bottleneck regardless of the order it travels.

You can with an MPPT charge controller. The output will drop the voltage and raise the current to keep the same watts and charge the 12V battery. Watch this video, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-V2b7z2eTb5o.html

You’ve got a difficult combination. The voltages of all 3 panels are very close, so a parallel configuration would be best. However, your battery is 24 volts, which means in a parallel configuration your solar panels won’t be putting out high enough voltage to charge 24V battery. So a series config will work for you, but you’ll lose a bunch of efficiency because the higher current panel will always drop down to match the lowest current panel in a series configuration. Yes, a series configuration will function with your mismatched panels, but it will not be providing optimum level of power.

Are you sure the battery bank isn't full and it is in float mode?

@@AltEStore yes the battery bank was 24.7v on multi meter. It was not fully chage

I believe your inverter will handle all 10 in series in. That is the best way. You should not parallel uneven strings, the lower voltage will suck down the higher voltage and you will lose power.

I love it!!!! Next sunny day, I'll be recording it (we have a stretch of bad weather coming up, then the holiday, give me a week or so). Thanks so much for the suggestion!

It depends on what your charge controller can handle for voltage input. Most MPPT controllers can't handle 360V input, unless it is a very expensive 600V controller.

@@AltEStore i have mpp solar. It handles 500 volt. I have a ? How much volt do I need to charge 450 amp (I have 4 6v trojan batteries) rem I have 16 of 100 watt solar panels (thats 360 volt ) do I need to add more panels or

Knowing the volts and amps are critical when designing a system, which is why all of the info is given.

It sounds like all 15 of your panels are wired in parallel…. So the answer to your question is “no”. The currents will simply add in direct proportion to the amount of sunlight they are each receiving. If the east facing panels are no longer receiving direct sun in the evening, they simply stop contributing. They have No effect on the other panels if wired in parallel.

The lower current panel pulls the whole thing down a bit, but not all the way down.

The same volts but different amps is better in parallel.

A 24V solar panel can charge a 12V battery with an MPPT charge controller. Watch the video we did showing it here, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-V2b7z2eTb5o.html. Are you sure it's only 2.4 watts, that's a rather odd size for a 24V panel. Perhaps 2.4 amps?

Just to clarify, you aren't asking about changing the voltage of one panel from 12 to 24V, because most panels don't let you do that, but are asking if you have a solar array that is wired as 12V, and you switch it to 24V. Charge controllers generally have a PV In+ and a PV In-. AS long as the charge controller is rated for the volts you are putting in, you don't change the connection to it, just connect plus and mins from the solar array to the charge controller. Let me know if that answers your question.

Yes. I would be changing the array. Looks like that's the easiest thing to do. If the existing wiring will take the new 24v panels, that's great. I'd be getting a new mppt controller as well.

Perfect.

no. not if the wire gauge is thick enough to carry the current. the wire can usually carry up to like 600volts. like 10gauge wire can carry like 30amps at 12 24or48 volts.for example. the charge controller may need to be changed. if they are not 24volt comparable.

Thank you so much, I'm glad you enjoy them. For a system that size, the difference is so small, it won't be noticeable. I would go with the 2 in parallel, and use a PWM.

Wow and you responded almost immediately! :) You guys are awesome. Serious thanks for the videos they are a great educational resource. I'm finishing my BSE in Mechanical Eng. and possible further education in Electrical Eng. I want to apply it to renewable energies, sounds like your team would be a great group to work with!

Your wish is my command. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-whFAPTWvWas.html

You read my mind! I have a few more scenarios to go, then will do a summary. Thanks for the feedback.

We have a whole playlist with many videos about charge controllers. They may help answer any other questions you have. ru-vid.com/group/PLoHd6hGDqS07wkAuvJ_p7_p76tMJRdyYy

+altE yes i already watched that video about mppt and pwm charge controllers thanks again for this great video!!

Correct. The 2 are just too different from each other to run on one together. Just connect both controllers to the battery, preferably through a breaker.

Thanks for that quick response Any much appreciated. Is a breaker like a fuse if yes what size would I need for each one. Cheers

Thanks. Great idea. You can check out the video James made many years ago testing a panel. It will give you the open circuit voltage (Voc) and open circuit current (Isc). ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-fkook28HhWI.html

No we don't. Anything in specific you want to see, or just a general overview. I love taking requests.

I have an Aimes 3000 watts/24 v pure sine wave inverter, actually two, not that I can combine them. but any who, I think I can use that transformer to change the 120 vac out to 240 vac to run a well pump, according to the duc you have online. But I might get a out of country 230 vac inverter later an looking for a transformer that would do both. My transformer theory is a bit rusty.

+Rev John O'Toole I have been thinking of something very similar . maybe just use a 220 230 240volt inverter. and build a transformer to put out two legs of 110-120v. any idea if this would work?

I will work on a video of using a transformer. Until then, you can see the install manual for the transformer here, www.altestore.com/static/datafiles/Others/PSX240%28900-0043-1%29.pdf . It shows that you can connect the 120V from your inverter into the inverter and it will step it up to a 240V output for your 240V loads, like the pump.

I think i have memorized the manual, I called your tech support one day and he told me to call Outback for my questions., but I have figured it out myself. I did mention I'll ask you at some point to get the right answer. enjoy the hoiliday

It depends on the inverter. If the inverter has multiple MPPT ports, you would be best to put the different tilt in its own MPPT port. IF that is not an option, you will see a change in performance. The amount of the difference would likely be different based on location. You can go to a tool like PVWatts to see the difference of an array at different angles for your area. That may help you get an idea.

Lead acid batteries like between 6 and 12 charge rate of their amphours. 200 / 12 = 16A - 33A.

This video discusses same volts, different amps. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-P3YtBrymJdA.html

You can wire that in parallel.

Oh thank you for that, because I doubt in that set.

People ask us this question all of the time. We decided to show them the answer.

@@AltEStore People are clueless then. Common sense should tell them solar panels are kinda like batteries, they are a source of power. You normally wouldn't (and shouldn't) connect 2 batteries in parallel if they have different voltages (such as a 12V battery and a 6V battery). That is asking for trouble. In my opinion, the average person should NOT be using solar. They don't have the knowledge to know what to do, especially if something goes wrong. My opinion is the power companies should have big ground mounted solar arrays away from trees, manage them, and beef up the grid to handle the increasing loads. That is the safest way. Look at all the problems people have with solar. Many solar systems cannot be used when the power grid goes down. What a waste! Many people don't want a roomfull of batteries. Too expensive, too much maintenance. Better idea... leave it up to the power companies to use solar and pay your electric bill. I wouldn't want all that crap up on my roof. Some roofs cannot even handle the weight of solar panels. I have seen fires from bad solar installations online. I have seen roofs ripped off (at a school I think) because of a bad installation. Too many problems with solar for the average person. Leave it to the experts (the power companies). Perhaps in some densely populated areas where there is a lot of sun, solar panels will help take some load off of the grid, but those places are few and far between.

That one's next, I'm editing it now.

+altE so nice of you

We just released the video you requested. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rBbVIiOBuT4.html Sorry about the delay.

+altE Thankyou very much, you are really a solar queen. :)

Depending on the MPPT charge controller, yes. Make sure the charge controller can take an input of at least 50V. See our video here where we use an MPPT vs a PWM with a 24V panel and a 12V battery. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-V2b7z2eTb5o.html

Thank you ! helpful info. Can I use this setup with a 12v power inverter?

If you are charging a 12V battery bank, you can use a 12V inverter.

Just to clarify further, what if the battery was at 10.5v 0%-capacity, vs the same setup with a battery at 13v 95%-capacity? I think the current out measurement could be quite different, and therefore watts produced very different as well. All constructive comments, btw - not criticizing.

Thanks for your input. We are working on improving our test setups for the upcoming spring. I know I need bigger batteries to help do the tests at a more consistent state of charge. I'm also adding more meters through out the system. Working on continuous improvement. Keep the suggestions coming, we do appreciate them.

Wonderful reply! Thanks for a great progressive attitude and desire to get it right. That's a value statement. Subscribed, and looking forward to more!

Actually, using a dummy load is more inaccurate, as it is not "real world values". You are better-off just using math and base-line values, if you think dummy-load tests are accurate. Those are only good for measuring scales, in controlled labs. We are interested in "reality", not "science experiments". My car goes 0-60MPH in 2.4 seconds on a dynamo. Put it on the road and it takes 4.5 seconds. Because it has uneven road surfaces, wind, starved air intake and uses the actual car computer to make real-world adjustments. Labs are useless for anything other than knowing how it will behave in a lab.

Absolutely. But many people get a mish mash of panels one way or another, and ask us if it makes sense to use them, and if so, how to wire them. So we thought we'd help them figure it out.

what I mean is the controller is rubbish - so in all intents and purposes your correct

Short answer: Don't do it.