Introduction: Connecting Multiple Solar Panels

Picture of Connecting Multiple Solar Panels

Connecting Multiple Solar Panels

Theses are the Diodes that I use, they are the same ones that are used when building the panels. Find them here.

There are 3 ways to connect solar panels; parallel, series, and a combination of parallel and series. The first way I am going to talk about is parallel because this is probably the most common way that panels will be connected. For this example I am showing you connecting panels that are for a 12 volt system. This is how the panels that I have built in my other instructables are connected, and feed my solar charge controller.

In this first image there are 3 solar panels. If you look at the arrows along the white and red lines they are showing the direction of flow. The white line is the negative connection, all 3 panel negative wires are just simply tied together and to the wire that runs back to the negative connection on the charge controller.

The red line is the positive connection to the panels. You will see a symbol that looks like a triangle pointing down at a horizontal line. That symbol is for a diode, also known as a blocking diode. What this diode is doing is only allowing the positive electrons to flow in only one direction. When looking at this symbol the triangle points in the direction of flow, when looking at the diode in your hand there should be a colored line around one end of it. This line represents the line in the symbol that the triangle is pointing to. The non-colored end would be the “in” side, and the end with the colored line around it would be the “out” side. By installing these diodes on each panel it stops the electrons from going back into other panels. Diodes also use up a small amount of voltage, so don't go crazy and put to many in or you will to low to use.

If you look below the panel to the left you can follow the red arrows from the panel down and make a right turn to the diode. Then they continue through the diode and down the line to the end where they would be connected to a solar charge controller.

Step 1:

Picture of

In this next step you can see that the left panel is covered, let’s say that a tree was blocking the sun from this panel.  If you look below this panel at the red line you will see that there are no arrows coming from the panel to the right hand bend. And if you look to the right of the diode symbol you can see that the arrows have changed direction from the previous step.  This is how the diode works.  The diode is stopping the electrons from pushing their way back to the panel that is not producing power.  If this diode was not in place then the panel not producing could be damaged.  Also you would be losing some efficiency from the other panels because they would be letting power flow through the nonproducing panel as the electrons are trying to reach the negative side of the panel.

Step 2:

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In this step I am showing you how to connect solar panels in a series configuration.  For this example we are going to say that the panels are 6 volt panels in a 24 volt system. Looking at the top image, start at the bottom right that is labeled – NEG.  Following this to the left you see that out of the other side of the panel the line is red, this is the positive side. With this being a 6 volt panel, and we need 24 volts we need to increase the voltage. To do this we connect the positive side of the first panel to the negative side of the second panel. There will now be 12 volts coming out of this second panel. Continuing up to the top left panel, there will be 12 volts in and coming out with 18 volts. Continue this through the fourth panel on the top right, there will be 24 volts coming out if this one.  You can also see the blocking diode here; it functions the same way as in the first example to keep from back feeding power into the panels.  These 4 panels wired up in this way work as if they are one large panel that produces 24 volts.  Having one blocking diode is the minimum that is needed in the circuit.

In the lower image the panels are connected in the same manner, positive to negative to reach 24 volts. In addition to blocking diode there are bypass diodes.  The reason for these are to allow power to go around a panel that is shaded by something.  It helps to keep that correct flow of power, not that it won’t flow in the correct way if their not there.

**Personal note** I have not seen any information on about efficiencies of panels connected in series with or without bypass diodes. I have not connected panels in this way either, all my panels are 12 volt and connected to a 12 volt system.

Step 3:

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In this step I am showing what happens when a panel is shaded by something such as a tree. You see that the bottom left panel is shaded, so the power follows the path around the blocked panel through the bypass diode. In this configuration you should be getting 18 volts.  This may not be charging a 24 volt system very well, but it will be adding some charge through amperage.  Less is better than none. If you have a higher end charge controller it may be able to use this lower voltage in some form, or maybe able to boost it back to the 24 volts to keep charging. You would need to check the specs on your particular charge controller.

If you do not install bypass diodes, as in the first image on the previous step, I do not see why all panels would stop producing power. They may just produce less power than if there were blocking diodes installed.  This is something that would have to be considered when building a panel system.  Is the loss in power worth the cost of extra diodes?

Step 4:

Picture of

In this step I am showing a combination parallel and series configuration. In this example we will be using 12 volt panels in a 24 volt system.  The 2 panels at the top of the image are connected in series of each other, and the 2 panels at the bottom are also in series of each other. These 2 rows of series panels are connected in parallel of each other.  So the top row produces 24 volts, and the bottom row also produces 24 volts.  Together both rows provide 24 volts there blocking diodes, then on to the collective point that would run back to the charge controller.  Because each row provides the same voltage, and they are in parallel the total voltage to the charge controller is 24.  The only time the voltages add together is when they are in series, like in each row.  2 panels that produce 12 volts each in series produces a total of 24 volts.  And in this example I also put in the bypass diodes.

Step 5:

Picture of

In this final step I am showing an example of a shaded panel in a combination parallel and series wiring configuration.  You can see that the top row is unaffected.  In the bottom row the left panel is shaded by a tree.  The top row will be producing 24 volts, the bottom row will only be producing 12 volts. Because of the blocking diodes at the end of each row the 24 volts will not push back into the row producing 12 volts.  You will be losing power because one of the panels are shaded, but they’re not going to back feed. You may still be gaining in amperage even though it’s at lower voltage if the battery needs the charge, or if there is another place for the power to go such as out to lighting or a tool. Again, less power is better than no power from panels.

Comments

akuini (author)2017-09-07

I have two solar panels both rated at 200watts each, unfortunately they hav different voltage. One is 36 volts and the other one is 16 volts. can hey work if i connect them in parallel and using a blocking diode for the panel with the lower voltage? do you think it could work with the blocking diode? thanks in advance!

tictag (author)akuini2017-11-03

I think you may have misunderstood the purpose of the blocking diode - this is only used to prevent the battery trying to 'power' the solar panels at night (or, to be more accurate, when the output voltage of the panel is lower than the battery voltage). The rule of thumb when connecting solar panels directly to a battery is never connect more than C/10 watts, where C is the capacity of your battery. For example a 110AH battery should never be connected to a panel more than 11W without a solar controller and, if you are using a solar controller, you do not need a blocking diode.

So, assuming you're using a solar controller...

The controller will have a 'maximum system voltage', which however you wire up the panels must not be exceeded e.g. series = 52v (36v + 16v = 52v). If this exceeds your solar controller's spec, the only option you'll have is to wire in parallel. If OK, you then need to look at the 'max power current' value. When connected in series, this will end up being the maximum current flow, irrespective of the power rating of the panels. So, for example, if one is rated at 8A, the other only 5A, you will only ever get 5A at 52V = 260W. Mismatches in current spec when connected in series will effect overall performance.

Parallel wiring in your case will probably be the worst option because, whilst the current will be additive, the overall system voltage will be limited to the lowest voltage panel i.e. 16V so, for example, you'll end up with 5A + 8A = 13A at 16V = 208W, which will inevitably be lower than a connection in series.

If I were you, and because solar controllers are usually a lot cheaper than solar panels, I would buy another solar controller and operate each panel separately.

Mismatched specification panels will always lead to a compromise in performance.

Steven A.S made it! (author)2017-10-29

i wanted to cut my three panel portable solar panel so it would fit better on my backpack, but now matter how i connect the terminals that were left, i can't create a circuit. I have included pictures. There are two positive and two negative poles. how are the supposed to be connected? Any advice?

joet6155 (author)2017-05-07

Sorry if this is a duplicate, I posted or thought I did, but it disappeared

My solar panel has 3 wires on it. It is rated: 90watts, 17.9volts, 5.03amps.

Has Black, White and Green wires. Black and White wires have a diode

between them with the top or "band" end on the White wire side. Could you

tell me the correct way to connect this to a charge controller that only has

a "+" and a "-" wire slot on it. Thank You

DiiK (author)2016-08-15

Direction of positive electrons? All electrons are negative. Positive atomic particles are called protons but only electrons (negative particles of atoms) flow in an electric circuit. Realizing that our culture is to accentuate the positive, eliminate the negative and don't mess with mister in-between, we must all relinquish our prejudices and realize that all of electricity consists of only the negative portion of the atom being pulled and tugged down the entire path of connectivity, while each electron knocks other negative particles of other atoms in, around and about in a forceful manner. Incidentally, the proton and the neutron form the atom's nucleus and the electron spins around the outer edge of that cluster. Electrons in diodes flow the direction from the arrow point into the wider part of the arrow, or for the banded diode they flow into the band and come out the other (bandless) end. The diode is a one way electron valve. The battery (-) is the source of electrons and the battery (+) is the absence of electrons, so therefore electrons flow toward the positive terminal via the external (to the battery) circuit. Negative (always) electrons flow from a battery minus to the battery plus. They flow into the diode symbolic arrow tips and bands and come out the other end of the diode, and only flowing one way.

陳亮 (author)DiiK2017-04-21

it just mixed up current and electron flow ?

x00 (author)DiiK2016-12-20

Positive electrons are called positrons like those in anti matter. Also diodes conduct in both directions. They have an avalanche or reverse breakdown voltage and will have this listed on their datasheet.

sunils68 (author)2016-11-21

best way to full charge a baterry is in parallel connection or series whatever the volt or amp ratings are

nzyachtcrew (author)2016-09-07

HI there. Interesting read. I think I understand the logic. I live on a boat that has 4x Shell SM110-24 (rated output 110w; rated current 3.15A; rated voltage 35V). Becuase of the mast and boom these is often a shadow that passes over one or more of the panels - often leaving the other panels fully exposed to direct light. From what I read the shadow on one panel is likely to be affecting the performance of the whole array. It's almost that I need each individual panel going back to the batteries individually - but thats a lot of wiring. What would be the best set up - series or parallel - and use of blockign diodes to minimise the impact of the shadow on one part of the array?. Cheers.

fireclawrd (author)nzyachtcrew2016-10-10

this is dependent on your battery and controller. but most likely parallel

fireclawrd (author)fireclawrd2016-10-10

or possibly combination depending on the voltage needed for your battery and controller

Africatwin69 (author)2016-08-12

Hi i am setting up a simple solar system to charge a 12v battery. It is a very budget kinda setup which i am not usig pwm or mppt. I have this voltage and current controller but even my panels are under the sun 3 different panels in parallel total 19.6v input but the current from the panel to battery is always 0.2a.
Do i need a diode or is there anything wrong with my setup?

Thanks in advance if anyone can help.

zappenfusen (author)2016-05-23

, http://amzn.to/1TtXMnQ This battery pack is NiMH not Lithium ion as stated. Nearly everything on Amazon is available through the multitude of Chinese suppliers on E-Bay. Most are free shipping, take forever to arrive but are the exact modules Amazon sells for 3 times the price. If you can afford to except the losses inherent with China post as you will receive the occasional bad, damaged piece you can save a ton of money. I've been ordering from China and the 2 month delivery times being the worst aspect have been mostly satisfied and can purchase 3 modules for the price of one on Amazon. When they do appear in your mail box it's like Christmas with the huge surprise! No Lithium is available though as shipment is prohibited even though they do offer strange, off brand lithium battery's I wouldn't trust as most state outrageous capacities. Just a thought on saving a lot of money and avoiding Amazon's attempt at World Domination! I'm a Prime member and Amazon is trying to take over my life! It's a Love/Hate relationship of historical proportions! Nice info on Panels.

zapp

ZoltánK12 (author)2016-05-20

Hello. I would like to build a solar charger for my phone to charge just like the wall charger. Do I have to buy 10 solar panels to produce 6V 1200mA and connect it paralell? One solar panel produce 6V 120mA. I would like to put an 5V usb step up module to the end. Thank you for your help in advance.

kalefranklin (author)ZoltánK122016-05-21

first you need to know what the charging current of your phone is. providing a little more than what it needs should be fine, but if you can provide double what it needs to charge there is a potential to damage your phone. some phones only require 500-750mA for charging.

Yes, when all the panels are the same voltage and you need to increase the mA you would need to connect the panels in parallel to produce the mA that you need.

its hard to charge directly from the panels. i suggest getting a small battery pack with a charge controller. you can let the battery charge all the time and it will be ready when you need it to charge your phone.

I started to build a charger like the one you are talking about, but I haven't had time to get back to it. it is also easier and cheaper to just buy one that is already made, but it is not as fun as building it yourself!

here are some links that may help you.

mini solar phone charger, https://www.instructables.com/id/Smart-mint-the-sol...

some parts i recommend to find and/or use, just be sure all the parts will work together before you buy:

--6-24v to usb modual, http://amzn.to/25eUkGw

--6v lithium rechargeable battery, http://amzn.to/1TtXMnQ

--a charge controller. all the ones i am finding are large ones, you may have to do some digging to find a small one or build one.

--small case

--solar cells, be careful what cells you use. i had some cells that after a week in the sun they cracked and pealed apart. here is a list that you can look through if you dont already had some picked out. http://amzn.to/1sw7P2F

if you want to go the easy way and just buy one here is a link, http://amzn.to/1TqETQA

as i was writing this reply i had am idea. you can connect your panels that you have with a USB cable on the end and then just plug it into a battery pack like this one-- http://amzn.to/1qAUqVS -- it already has the charging circuit in it, and all the ports you need. with this set up you can easily take a charged battery pack with when you need it and plug it back in later when it needs charged.

i hope that i have helped and not confused you even further. i may have to build my own in the near future, and finish it this time!

WikiR (author)2015-07-09

Sir i have two solar panels 150W with same amp and voltage as you can see in the below picture. And I have a UPS, Sir i wnat to coonect these two plates with ups so which method should I chose SERIES OR PARALLEL

Jlobel0 (author)WikiR2016-05-06

You require a parallel conection , a blocking diode and a regulator to keep your 12v ups charged (if 12v ups)

DatacorpE (author)2016-05-05

I have a question that if we join 2 solar panels of 4 volts and 100 mah then what will be the output (__volts ___ mah)?

Jlobel0 (author)DatacorpE2016-05-06

In parallel you will have 4v and 200mv theoretical, in serial 8v and 100ma

Jlobel0 (author)DatacorpE2016-05-06

In parallel you will have 4v and 200mv theoretical, in serial 8v and 100ma

ufoexpert (author)2016-03-06

I installed 2 150 watt panels with a 30A controller. I just installed another 2 150 watt panels (same type) when I went to run the 4 panels to the controller it shut down. Question I have 4 t-605 batteries , can I use another controller and feed the 1 set of batteries and another controller to feed the other set? These 4 solar panels from what I read will produce 50 amps.

KristopherH2 (author)2015-10-06

i have a bunch of 3-6 v solar panels ( yard accent lights that have been thrown out due to batteries being dead.) im trying to figure out the best way to chain them all together and make a 12v array it is understood that i might have to use a couple different methods to do this. the first step im looking for is to make the panels all equal 12v that would be a parallel connection if im understanding this correctly then i would need toput them into a series to pump up the amperage? also im currious if i were to use one of the charge controling chips from said light would that work?

hellzwells (author)KristopherH22016-01-14

The controller chips in those yard accent lights just monitor the voltage produced by the solar cell (during the day), and while the voltage is above a threshold a rechargeable battery is trickle charged (for example, a "2/3 AA" 1.2V 150mAh inside the $1 walmart yard lights). Likewise, when the voltage from the solar cell drops below a threshold (at night), the controller turns on the LED with the power from the battery. Not sure if this helps with your last question.

I would not recommend making an array with cells that have different ratings. The current output of a series connection will be limited by the cell with the lowest current rating. You would need to include suitable bypass diodes between each cell to prevent overheating (and possible damage) and even then your panel will not be very efficient working in that way.

Answering your question: NO. To increase the output current you'd add cells in parallel (voltage remains the same or an average of all cell's voltages if they are different) , to increase the voltage you'd add cells in series ( the current again, would be limited by the cell with the lowest current rating). I'm attaching an example .

Assuming that each panel was rated at 5V and 0.5 amps

jimmyg03 (author)2015-11-25

Hi
I am setting up a solar array and would like a little information if you peeps could help here is the equipment i have at the moment
15 x 315w lg neon2.
1 x outback flex 80.
1 x victro 5kw 48v.
Now i was thinking of putting it like this
5x3 in series thus getting around 99v but only 9 odd amp per three panels.
My question is .
I will be using normal 4mm cable with mc4 connectors for each array of 3.will i have to step up the cable size when they are joined together say 6mm or even 10mm as the total amp at max is around 45amp is it not
? Or am i missing something here.TIA

ChristoJ (author)2015-07-06

hi there

I have a 6000W 48V inverter with 60A (MPPT)charge controller. I have 16 275W (21V) mono solar panels. What is the best way to connect these panels in an array to get maximum efficiency. (how many in series , how many in parallel?) I tried 4 series, and 4 parallel, but the amps from the charger is very low (aprox 14amp)

kind regards

Christo

DanM89 (author)ChristoJ2015-11-22

You have the best configuration.

With your configuration, 4 x 4 you should be seeing 84V @ 52 Amps or 4,360 Watts DC. Most likely there is a problem.

Disclaimer

Warning before doing the following testing wear rubber gloves suited to protect from getting a electrical shark. Any voltage over 40v will give you a shark. Always connect the panels LAST, after connecting everything else.

This is not for the faint hearted. Since most solar arrays are install on the roof or high places, you should be wearing a secured harness, to protect from falling. It maybe best to get professional help.. I take NO responsibility for any harm caused in preforming the following trouble shooting. Again I stress get help from a professional. To proceed, the risk is your's and your's alone.

The best way to test any part of a high current solar panel array is to use a resistive load. There are good resistive loads that can be purchased, and used with an ampere meter, for more accurate indications.

A cheap resistive load test can be constructed using 4 x 250 w @120vac incandescent light bulbs (don't use fluorescent) wired in PARALLEL forming a 1000 watt load. Connect this load to one of the 4 panels set in series. 84v @ 13 amp supplies about 1,093 watts, with strong sun. Might use 3 X 250, if the sun isn’t that strong where the panel output is reduced.

Only apply this load to sections that are broken down to 800 to 1,200 watts. As in this case each section of 4 panels in series, supply about 1,100 watts. Each section must be completely disconnected from the rest of the array. For tests over 1000 watts, only connect for a very short period, less then 1 second, as bulbs may be damaged.

Follow through the system, checking next the output of the charge controller and the output of the inverter. At the inverter output the supply is regulated to 120 vac, bulb damage isn’t a concern.

As you, descend from the panels to the charger to the final output side of the inverter, there will be slight dimming due to losses in each.

amans49 (author)2015-11-21

can you tell me please about

controlled diod so i will purchase

MustaphaJ2 (author)2015-10-13

What if I have 24v system how am I to connect

Moath aladimi (author)2015-08-22

Dear sir Is it possible to connect more than different voltage solar panel and the ability, for example, 30-volt 250-watt and 250-watt 37 Volt

ChristoJ (author)2015-07-06

SevP (author)2015-05-02

Glad to see that the person directing ALL THESE PEOPLE to connect their solar panels together knows all about the 'POSITIVE ELECTRONS'. Them pesky positive electrons, always trying to travel a direction they ain't supposed 'ta!

And darn those diodes, because they 'use up a small amount of voltage', because, you know, that's totally a thing that can be used up. Learn some basic electrical engineering before you write an article that will be used by countless people in potentially dangerous situations.

Chamber12 (author)SevP2015-05-26

Agreed. The theory from what I read seems right, but as soon as I got to 'positive electrons' it's obvious anyone who has not actually studied this just became confused, or got the wrong idea of the way the system works and could very well cross-connect something later and cause damage or wounds.
Teach correctly or stay out of the way, we're dealing with something that literally kills thousands every year, and this is far from the first link I've clicked on while looking for references.

IrfanA5 made it! (author)2015-04-29

if you want to charge 2(double Battery )then see series and if single then see parallel circuit

IrfanA5 (author)2015-04-29

MUHAMMADB4 (author)2015-04-25

Hello
I need to known how many combination are possible for solar plates.I have 3 solar plates of 150 Watts,12 volts and 8 amperes,Which combination is best for using with a ups battery of 180 amps? I have liquid battery. I am from Pakistan. My email id is bilalengineer313@gmail.com

simon.marshall.9889 (author)2015-04-23

Do i need the blocking diodes if im using a charge controller?

gautam.singh.90834 (author)2015-04-17

dear sir,please tell me some advantage and disadvantage of connecting two dc- dc converter (boost circuit) in series? what is its effect if we connect two boost converters in series and feed there output to delta inverter ( 5kw)??

ta_ss (author)2015-03-31

Dear sir, i have gone through, the article its very useful, can you explain the consequences if we use different wattage panels, what kind of connections we would prefer. I have three 20 watts panels and four 10 watts panels

graphixv (author)2015-02-22

What type of circuit would you need to build in order to be able to switch the panels from series to parallel? I'm going to have 2 100 watt 12 volt panels. I'm planning to add an AC inverter to supply power to the house which requires them to be in a series for 24 volts. But, I already use one panel with a 12 volt back up battery system that I want to keep as-is, which means I'll need to be able to switch them to parallel to provide 12 volts to the charge controller/batteries.

kalefranklin (author)graphixv2015-03-26

if you are going to add an inverter why not just add a 12v inverter? i hope you are not planning on running your entire home on 200 watts because you will not be able to do much with only 200 watts. is this a grid tied inverter? i have a grid tie inverter in my solar setup. i have a controller that when my battery bank is full it switches my incoming solar power to my grid tie inverter so it helps reduce my electric bill, but only by a few dollars a year because i only have a small amount of panels.

graphixv (author)kalefranklin2015-03-26

Thanks for the reply,

Let me explain.

I just wanted to do this because a lot of the decent grid tie inverters take a minimum of 24 volts, where-as, my battery backup (Twin 6 volt golf cart batteries at 180 amp storage) the panels charge is 12 volts. (question about this below).

And yeah, like you, I just wanted to feed a little AC into the house to offset some of the power used by say a window AC unit. I already have the panels for the backup so I figured why not also offset the cost a little by using the power when my batteries are charged (As a backup this is almost all the time).

The main problem is - there doesn't seem to be a very reliable grid tie inverter available which suits my needs. Doesn't make much sense to buy an inverter that is going to blow up in two years, replacing it costs more than the 125-150 watts I'm going to pulling off of it here and there. Buying a grid inverter that costs $300 doesn't make sense because it will take 10 years (if it lasts that long) to break even. This system is also too small to go through the exhaustive work of hard installing something that outputs 240 volts to a specialized panel.

One final weird question about the backup system. Up to now, every blue moon when the system has been running (only 400 watts), I've ran extension cords to various things to run them. * If I disconnect my home from the grid at the panel box during an outage by throwing the main disconnect, could I possibly run the inverter into an electrical outlet and therefore not require extention cords? * Or does turning off the main panel switch also disconnect the outlet circuits? I'm trying to get away from requiring extension cords.

Obviously, if I could do this the backup would be completely removed before the grid is reconnected by turning the panel back on and I would need to disconnect items like the refrigerator, furnace etc.

Hope that explains things a bit.

rover419 (author)2015-02-07

dear sir, I have lived off grid over 10 years. I have run into a situation that no one, including me ,can seem to figure out. Would you be interested in hearing my solar / wind dilemma

vinz3nt (author)2015-02-02

Hi,

Thanks for the clear explanation.
I was wondering, I don't use a lot of diodes and I have some IN4001, IN4002 and IN4003 diodes lying around (I think the only difference is the voltage). Are these sufficient?

Thanks!

evert.pitout (author)2015-01-03

Hi

I have a 5W PV Solar Power Panel 12V Battery Charger Boat Marine, 5Watt Trickle Charge CAR and 12V KIT Offer ISTA-BREEZE® i-500 Small WIND GENERATOR + Charge Controller.

Will this be sufficient to run 15 to 20 KwH household per day?

no. you need a lot more generation and storage before you even come close to your power needs. if you are using 20 KwH per day then you need to be producing more than that amount and store it so you have power at night.

gphat (author)2014-08-29

my GTI has MPPT function. Is there any lost when some of panel is shaded if I dont have diode in panel

kalefranklin (author)gphat2015-01-21

depending on the quality of the MPPT it may have a diode internally. you would have to do some research to know for sure.

lelegriccioli (author)2014-09-18

So what is the advantage of putting them in parallel?

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