12 Volt Panels for a 24 Volt Sytem?

[Trail Ninja]

Noob needs help wrapping brain around the following...

I plan on building the 2000 W 24 V system that Will provided blue prints for on mobile solar power. I am purchasing the components through the provided links to Amazon.

Before I get started I wanted to confirm that 12 V solar panels can be used in a 24 V system? I realized that the charge controller must be the key to this, but can someone explain what it is that's going on inside that Box.

RV Solar Power Blue Prints

Building a vehicle mounted solar power system? Let me help.

www.mobile-solarpower.com

Trail Ninja out.

 

[nosys70]

you need to check the PV voltage input range form your SCC
anyway panels can be mounted serial, so a multiple of 12V is possible.
usually, a PV voltage higher than the battery/inverter voltage is welcome to ease the work of the electronic.

 

[Trail Ninja]

In the above link's schematic, thre are three solar panels wired in series, for a total of 36 volts correct? There are only three panels in the schematic. Is there a reason for this?

 

[Bob142]

In the above link's schematic, thre are three solar panels wired in series, for a total of 36 volts correct? There are only three panels in the schematic. Is there a reason for this?

I believe that's just a general representation of a PV array rather than an explicit recipe. There are many ways to achieve the stated 1000W of PV in the diagram. You don't have to buy a ton of 12V 100W panels to get there. In fact, it's more cost effective to buy fewer larger panels. As an example, take a look at the listings at altEstore.com. Sort the table by the $ / Watt column and you'll see what I mean.

Buy Solar Panels - Solar Panels for Your Home, RV, Boat | altE

Shop our wide selection of solar panels from top brands for your home, cabin, RV or boat. Quality solar panels at affordable prices with expert service.

www.altestore.com

Ultimately it comes down to your use case: if you're mounting this system on an RV you have to figure out how many panels you can fit up there and a lot of times it's only the 12V panels that will work. If you're doing a stationary system on your house roof or a ground mount you probably have a bigger area to deal with and you can go to the higher voltage panels etc. Will has a separate page for solar panels and if you scroll down you'll see there are also tremendous deals to be had on larger used panels.

Vehicle Mounted Solar Panels

Building a vehicle mounted solar power system? Check out my site. This page covers solar panels

www.mobile-solarpower.com

 

[Forbisher]

In the above link's schematic, thre are three solar panels wired in series, for a total of 36 volts correct? There are only three panels in the schematic. Is there a reason for this?

Three 12 volt panels in series are over 60 volts.
Explained in detail on this post.

24 volt off grid

Have a question, I have 4 165w panels, 22.46v. If I set up a 24v array (2 each at 12v to get 24v from 4) how do I determine voltage for the right mppt charger?

diysolarforum.com

 

[Trail Ninja]

I think I'm starting to get this.
12 V panels need to be wired in series for a 24 V battery bank system to receive a charge. As long as they the panels do not exceed the maximum input voltage of the MPPT solar charge controller, I can add as many panels as I want/need.

I'll take a look at the charge controller specs to see what the min and max inputs are.

Thanks.

MPPT: EPEVER MPPT Solar Charge Controller 40A 150V PV Solar Panel Controller Negative Ground W/ MT50 Remote Meter + Temperature Sensor PC Monitoring Cable[Tracer4215BN] https://www.amazon.com/dp/B07429RK43/ref=cm_sw_r_cp_apa_i_H1MzEbPJ0QJ97

 

[Trail Ninja]

Three 12 volt panels in series are over 60 volts.
Explained in detail on this post.

24 volt off grid

Have a question, I have 4 165w panels, 22.46v. If I set up a 24v array (2 each at 12v to get 24v from 4) how do I determine voltage for the right mppt charger?

diysolarforum.com

Thanks.

 

[offgriddle]

Noob needs help wrapping brain around the following...

I plan on building the 2000 W 24 V system that Will provided blue prints for on mobile solar power. I am purchasing the components through the provided links to Amazon.

Before I get started I wanted to confirm that 12 V solar panels can be used in a 24 V system? I realized that the charge controller must be the key to this, but can someone explain what it is that's going on inside that Box.

RV Solar Power Blue Prints

Building a vehicle mounted solar power system? Let me help.

www.mobile-solarpower.com

Trail Ninja out.

Hello Fellow Beginner!
This past summer I wired up my two, 12 volt panels in series to make 24 volts. This is the little diagram I made up before hand. If you have any questions feel free to ask!
OG

 

[Trail Ninja]

Yes I am starting to get some clarity. One of the things that was answered in this thread and the link to one of the other threads is that a 12 V panel operates at about 20 V.

Once I learned that and I looked at the SCC's voltage input range, it clicked.

 

[offgriddle]

Yes I am starting to get some clarity. One of the things that was answered in this thread and the link to one of the other threads is that a 12 V panel operates at about 20 V.

Once I learned that and I looked at the SCC's voltage input range, it clicked.

Yes, the maximum voltage output of the panels must be taken into consideration with SCC input calculations. My 12 volt panels produce under no or very light load 18 to 22 vdc each so times two, (in series), I am reading about 41 or 42 volts reaching the input of my SCC in full sun when the batteries are satisfied.

 

[Trail Ninja]

@offgriddle, What components do you use in your 24 V system?

 

[Trail Ninja]

Something else I learned from one of Will's DIY solar videos is that when solar panels are cold they put out more voltage. He said that this is an important consideration when you're solar array is reaching the maximum input voltage of your charge controller; I'm not sure if Will said this was a problem for all types of charge controllers or a specific type?

Is there a recommended Percentage cushion?

 

[offgriddle]

@offgriddle, What components do you use in your 24 V system?

Lets see, I began with solar about 5 years ago with 200 amps of Trojan flooded lead acids and a Windy Nation PWM, (pulse with modulation), SCC, (Solar Charge Controller), an off the shelf 800 watt 12vdc-120vac inverter from the auto parts store and an old 6 amp shore power charger that was powered by the generator. I also purchased two, 100 watt, 12 volt Windy Nation poly crystalline solar panels.

I DID NOT like that at all, (lol in defense of the batteries I abused the lead acids horribly by discharging them way down beyond what I should have and leaving them deeply discharged often and I never operated the generator long enough to ever give the batteries a full charge). I upgraded a little bit last summer.

Last summer, I purchased two 20 ah, (don't laugh I am somewhat poor), lifepos with built in BMS and a brand new MPPT Epever Tracer 4215 BN with MT-50 control panel and a ten amp lifepo shore charger. I also wired my panels from 12 volts 24 volts, (I confess that I am currently using three, ratty,14 gauge, extension cords wire nutted together for my 100' panel to SCC run). I still have the same inverter and I love it it's bullet proof.

The Lead Head is Dead: Even as wimpy as my system currently is, my recent, modest, upgrades produced a night and day difference and I am extremely happy with the amazing amount of power I am currently enjoying and I am spurred on for more!

Future plans:
I found out later that my lifepos cannot be wired in series but thats OK I plan to upgrade and donate my current lifepos to the needy.
I will calculate for the correct present and future amperage and wire gauge and use continuous length stranded copper wiring.
I of course need more panels and a proper panel mounting rack and will calculate accordingly.
My ultimate goal is to power a 24 volt DC, 4,000-5,000 watt 240 volt AC inverter and feed my main panel through a simple, manual switch that can be either inverter or generator, (I have no grid).

Thank you for asking, what about your plans?

 

[ghostwriter66]

MPPT: EPEVER MPPT Solar Charge Controller 40A 150V PV Solar Panel Controller Negative Ground W/ MT50 Remote Meter + Temperature Sensor PC Monitoring Cable[Tracer4215BN] https://www.amazon.com/dp/B07429RK43/ref=cm_sw_r_cp_apa_i_H1MzEbPJ0QJ97

My favourite GO-TO SCC and monitor ...

 

[offgriddle]

Something else I learned from one of Will's DIY solar videos is that when solar panels are cold they put out more voltage. He said that this is an important consideration when you're solar array is reaching the maximum input voltage of your charge controller; I'm not sure if Will said this was a problem for all types of charge controllers or a specific type?

Is there a recommended Percentage cushion?

Solar panels are more efficient when cold, the produce less when they are hot, I don't know how to calculate that or if it is necessary for typical situationss.

 

[ghostwriter66]

Something else I learned from one of Will's DIY solar videos is that when solar panels are cold they put out more voltage. He said that this is an important consideration when you're solar array is reaching the maximum input voltage of your charge controller; I'm not sure if Will said this was a problem for all types of charge controllers or a specific type?

Is there a recommended Percentage cushion?

For voltage i would push it right to the 100% mark .. for amperage -- I push it to 120+% of the recommendation ... (then again i also never wore a bike helmet )...

 

[ghostwriter66]

Solar panels are more efficient when cold, the produce less when they are hot, I don't know how to calculate that or if it is necessary for typical situationss.

Honestly there is no need to at this point -- the difference for what you are doing is marginal ...

 

[ghostwriter66]

Noob needs help wrapping brain around the following...

I plan on building the 2000 W 24 V system that Will provided blue prints for on mobile solar power. I am purchasing the components through the provided links to Amazon.

Before I get started I wanted to confirm that 12 V solar panels can be used in a 24 V system? I realized that the charge controller must be the key to this, but can someone explain what it is that's going on inside that Box.

RV Solar Power Blue Prints

Building a vehicle mounted solar power system? Let me help.

www.mobile-solarpower.com

Trail Ninja out.

what panels are you getting??? .. panels change their prices a couple times a month ...

 

[offgriddle]

what panels are you getting??? .. panels change their prices a couple times a month ...

Hi GW, I've not selected a model or brand yet. To save on shipping costs I guess I will stay with the 100 watt panels and also to facilitate mounting arrangements, neatest looking installation and uniformity but i must confess that the 250 and 300 watt panels are tempting; I'm not sure what if any advantage there would be over staying with all 100 watt panels .. your thoughts?

 

[ghostwriter66]

Hi GW, I've not selected a model or brand yet. To save on shipping costs I guess I will stay with the 100 watt panels and also to facilitate mounting arrangements, neatest looking installation and uniformity but i must confess that the 250 and 300 watt panels are tempting; I'm not sure what if any advantage there would be over staying with all 100 watt panels .. your thoughts?

For me i typically go with the largest that my SCC can handle and that i can safely mount ... 100's are pretty small and it takes the same effort and time and material to mount a 100 as it does a 300 ... Check Amazon and EBay for some good deals ...