Recommendations for small charge controllers with real MPPT


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harrisonpatm

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Joined
Jan 5, 2022
Messages
107
As I'm learning about solar, I'm trying to design some small systems for practice, for my shed or self-contained power pack or bike charging, ect. I also am a fan of multiple redundant systems anyway, so even when I get to the point of having one big system for the house, I'll still plan on several small systems being in place.

Does anyone have any experience with this one? I'd prefer if I could get some options with true MPPT, and it's hard to tell if a module that lists MPPT actually uses it, or if that's just lying clever marketing tactics. Also if there was something else more in the range of 10-30A as well that's not too expensive, rather than the 5A chip I linked, I'd like to play with other options. I know that the higher amps means more expensive, but still...

Thanks in advance!
 

italianuser

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Joined
Feb 25, 2020
Messages
504
I started off in 2020 with a small 100W (2x 50W panels) 12V solar system using a cheap MPPT controller. Usually the MPPT controller has a relatively big inductor in it, at least the ones I searched. I've never seen that board you shared.

I documented the project in my blog, you can see it here (the article is in italian language, but Google translates it quite well): https://electronic-acca3-it.transla...l=auto&_x_tr_tl=en&_x_tr_hl=it&_x_tr_pto=wapp

I chose the CPY-2420 20A MPPT controller after quite a bit of research and went for a low bugdet true MPPT controller. I checked many online reviews before buying it, and found reviews where they do open the box and look inside. It's a 12/24V autoswitching model, so you could have panels+battery+inverted in one configuration or the other. I bought it for under 20€ (20USD), the price is more or less that.

fotovoltaico.jpg

To make the system my first choice was the general voltage to use: 12V or 24V. Being my first system I went for the easiest and cheapest, that is 12V. I'll most probably be expanding it to 24V sooner or later. So:

- Panels are now 4x 50W polycrystalline. Because of bad orientation they make at best 110-120W instead of nominal 200W. Cables I used for the panels (from panels to controller) are 2.5mm2 (13AWG) for each couple of panels. Cable is nearly 10 meter long (30 feet) and gets slighly warm when maximum current passes through them.
- Batteries are now 5x 12V 9A AGM Lead-acid in parallel. These LA batteries aren't the best choice I suppose. You can actually use less than 50% of the nominal capacity. You can find some load tests I made in the article I shared. But this controller only supports LA batteries, so I'll stick onto these for now. I found a good make at a good price (british Ultracell batteries), I would avoid any low quality battery;
- Inverter is a 1000W chinese pure-sine wave (around 35€/35USD), works well, I usually keep it at a really low load, around 30-40W (my notebook, a cellphone battery charger);
- The security stuff I added are also described, on DC side: an MCB switch to cutoff panels, 2 fuse holders with 20A 10x38 fuses between battery and inverter; on the AC side a 10A MCB on the inverter's output and an energy meter (this is a must! Keeps track of voltage, current load and how much current goes trhough it).

What I didn't implement is the autoswitch from solar to grid.

[ The article contains a link to buy the controller - it's an affiliate link, I get a bunch of coins if you buy using it! ]
 
Last edited:

harrisonpatm

Member
Joined
Jan 5, 2022
Messages
107
I started off in 2020 with a small 100W (2x 50W panels) 12V solar system using a cheap MPPT controller. Usually the MPPT controller has a relatively big inductor in it, at least the ones I searched. I've never seen that board you shared.

I documented the project in my blog, you can see it here (the article is in italian language, but Google translates it quite well): https://electronic-acca3-it.transla...l=auto&_x_tr_tl=en&_x_tr_hl=it&_x_tr_pto=wapp

I chose the CPY-2420 20A MPPT controller after quite a bit of research and went for a low bugdet true MPPT controller. I checked many online reviews before buying it, and found reviews where they do open the box and look inside. It's a 12/24V autoswitching model, so you could have panels+battery+inverted in one configuration or the other. I bought it for under 20€ (20USD), the price is more or less that.

View attachment 27449

To make the system my first choice was the general voltage to use: 12V or 24V. Being my first system I went for the easiest and cheapest, that is 12V. I'll most probably be expanding it to 24V sooner or later. So:

- Panels are now 4x 50W polycrystalline. Because of bad orientation they make at best 110-120W instead of nominal 200W. Cables I used for the panels (from panels to controller) are 2.5mm2 (13AWG) for each couple of panels. Cable is nearly 10 meter long (30 feet) and gets slighly warm when maximum current passes through them.
- Batteries are now 5x 12V 9A AGM Lead-acid in parallel. These LA batteries aren't the best choice I suppose. You can actually use less than 50% of the nominal capacity. You can find some load tests I made in the article I shared. But this controller only supports LA batteries, so I'll stick onto these for now. I found a good make at a good price (british Ultracell batteries), I would avoid any low quality battery;
- Inverter is a 1000W chinese pure-sine wave (around 35€/35USD), works well, I usually keep it at a really low load, around 30-40W (my notebook, a cellphone battery charger);
- The security stuff I added are also described, on DC side: an MCB switch to cutoff panels, 2 fuse holders with 20A 10x38 fuses between battery and inverter; on the AC side a 10A MCB on the inverter's output and an energy meter (this is a must! Keeps track of voltage, current load and how much current goes trhough it).

What I didn't implement is the autoswitch from solar to grid.

[ The article contains a link to buy the controller - it's an affiliate link, I get a bunch of coins if you buy using it! ]
Thanks for the info! You reminded me to look for a big ol inductor of some kind on any controller I get.

That controller you linked to looks great, except you say it only supports LA, and I was hoping to use all my salvage lithium batteries. Good info though!
 

OffGridInTheCity

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Joined
Dec 15, 2018
Messages
2,077
There's a youtube channel @Adam Welch - and he has reviewed many smaller MPPT/PWM charge controllers. Search "MPPT" and you get a good list of youtubes that might interest you, including building your own!. Here's an example....
View: https://youtu.be/TfB_iIF-rCA


In the early days I used EPEVER ( https://www.amazon.com/EPEVER-Controller-Negative-Grounded-Regulator/dp/B01BXRIRQC?th=1 ) and found it a good solid (lower priced) MPPT unit. They make several models and with the MT50 remote box ( https://www.amazon.com/EPEVER-Suitable-Tracer-Tracer-BN-Controller/dp/B07QRZYWV4/ref=sr_1_3?crid=3RNFI27GE757J&keywords=epever+remote&qid=1652556070&s=lawn-garden&sprefix=epever+remote,lawngarden,150&sr=1-3 ) you can do user custom settings. @Adam Welch has some youtubes on EPEVER enhancements for remote monitoring.
 
Last edited:

harrisonpatm

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Joined
Jan 5, 2022
Messages
107
There's a youtube channel @Adam Welch - and he has reviewed many smaller MPPT/PWM charge controllers. Search "MPPT" and you get a good list of youtubes that might interest you, including building your own!. Here's an example....
View: https://youtu.be/TfB_iIF-rCA


In the early days I used EPEVER ( https://www.amazon.com/EPEVER-Controller-Negative-Grounded-Regulator/dp/B01BXRIRQC?th=1 ) and found it a good solid (lower priced) MPPT unit. They make several models and with the MT50 remote box ( https://www.amazon.com/EPEVER-Suitable-Tracer-Tracer-BN-Controller/dp/B07QRZYWV4/ref=sr_1_3?crid=3RNFI27GE757J&keywords=epever+remote&qid=1652556070&s=lawn-garden&sprefix=epever+remote,lawngarden,150&sr=1-3 ) you can do user custom settings. @Adam Welch has some youtubes on EPEVER enhancements for remote monitoring.
Excellent, thanks, I'll dig through those vids
 

harrisonpatm

Member
Joined
Jan 5, 2022
Messages
107
There's a youtube channel @Adam Welch - and he has reviewed many smaller MPPT/PWM charge controllers. Search "MPPT" and you get a good list of youtubes that might interest you, including building your own!. Here's an example....
View: https://youtu.be/TfB_iIF-rCA


In the early days I used EPEVER ( https://www.amazon.com/EPEVER-Controller-Negative-Grounded-Regulator/dp/B01BXRIRQC?th=1 ) and found it a good solid (lower priced) MPPT unit. They make several models and with the MT50 remote box ( https://www.amazon.com/EPEVER-Suitable-Tracer-Tracer-BN-Controller/dp/B07QRZYWV4/ref=sr_1_3?crid=3RNFI27GE757J&keywords=epever+remote&qid=1652556070&s=lawn-garden&sprefix=epever+remote,lawngarden,150&sr=1-3 ) you can do user custom settings. @Adam Welch has some youtubes on EPEVER enhancements for remote monitoring.
I'm certainly not through all of Adam Welch's vids yet, but what I'm finding most interesting is the high number of charge controllers labeled as MPPT that aren't. Which is what I expected, hence this post asking for advice. Lovely to know I had the right idea to research a bit before buying.
 

ajw22

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Joined
Nov 16, 2018
Messages
680
Does anyone have any experience with this one?

I don't have hands-on experience with that specific module, and the description has a very bad case of chinglish. But it very much seems like it's in fact NOT a true MPPT charge controller, because it seems to have an adjustment pot to manually set the target input voltage of the attached solar panels. I believe when they say "MPPT", what they actually mean is "target input PV voltage is manually adjustable".

It could perform quite well if the panels stay at very similar temperature all the time, or you keep adjusting the input voltage pot every few months.
If not, and the panels get hot... horribly poor performance.
Eg. Have a look at the following graph. When the temperature is 10C (say early spring), the ideal voltage is 18V and provides 53.8W of output . But come summer when the panels reach 55C, the output will plummet to 5W when the input voltage is kept at 18V.
 
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