Opinion of this renogy PWM charge controller?

[XERTYX]

[font=Tahoma, Verdana, Arial, sans-serif]So I found this charge controller on home depot's website. It's a renogy 20A controller 260W 12v or 520W 24 volt system. [/font]


https://www.homedepot.com/p/Renogy-...olar-Charge-Controller-RCC20VOYP-G1/312154300

[font=Tahoma, Verdana, Arial, sans-serif]I know renogy has a good reputation. Definitely better than the no name chinese 10A controller I use now with my stationary SLA alarm system battery bank.[/font]

[font=Tahoma, Verdana, Arial, sans-serif]I'm hoping to soon buy a van and if I have enough space on the roof to order 2 250W panels from santan. Ideally i would want to have 2 controllers, 1 for each panel both with the same charge parameters ran into 1 bank of group 29DC walmart deep cycle batteries.[/font]

[font=Tahoma, Verdana, Arial, sans-serif]I know Bob has in the past reccomended (or maybe suggested I forget exactly) having 2 charge controllers. Built in redundancy. 1 controller fails you still have half of your system operational. I also know that as long as both controllers are the same technology (i.e. PWM/MPPT) and both have the same charging profiles (float voltage etc) then it works just fine.[/font]

[font=Tahoma, Verdana, Arial, sans-serif]The idea of redundancy appeals to me to a great deal. Also I'd like in the future to build a small cabin and these controllers claim to be waterproof so I could later repurpose them and have a little more insurance not to fry the controllers if I do build a solar array and battery bank with inverter and run the AC back to the cabin. Just a few ideas. Anyway getting off topic... the price on these are double the price of a random chinese no name brand controller, they're also half the price of a fancy dancy ones that have bluetooth, wifi, and can make french fries in 3 different fashions.[/font]

[font=Tahoma, Verdana, Arial, sans-serif]In my experience the el cheapo controllers do not always read true re: voltage even between identical units. So using 2 crappy controllers seems like a recipe for failure to me. These dont seem to be a piece of crap. Moderately priced. A known brand in the solar field. It seems like a win to me.[/font]

[font=Tahoma, Verdana, Arial, sans-serif]Thoughts? Opinions?[/font]

 

[wayne49]

Renogy units are manufactured where most everything is manufactured these days. China.

I have two Renogy units, a Commander 40A, the other a Rover 20A, that read different bank voltages, a constant difference of 0.3 V. It happens.

A local Home Depot may not stock that unit in store. Pahrump's HD does not.

Buying direct from Renogy, the unit is $49.99. Home Depot price is $48.46.

 

[user 423]

Two years ago I bought a Renogy kit w/single 100w panel and a 30A Wanderer PWM (really basic also).

I never thought about redundancy since in my experience most electronics are pretty reliable and also because my budget for stuff is pretty lean.

If the controller fails I have a small generator and charger that I can use to keep the batteries topped up.

Unless I'm way out in the boonies, it wouldn't take but a few days to snag a new controller off Amazon,etc.

If that day comes, I will then order an inexpensive MPPT controller and maybe an extended warranty.

 

[Trebor English]

What I do is use my "good" voltmeter to measure the voltage at the battery and adjust the controller to get what I want.  The controller can't tell you the voltage at the battery while it is feeding 5 to 10 amps into a cable of unknown (to the controller designer) length and size. 

If you have 2 controllers feeding one battery bank one controller will detect the shutdown condition first and stop charging by switching to float mode.  Your battery gets 20 amps for a few hours then the max voltage is reached.  Then the amps taper off.  Does it matter if both controllers put out 2.5 amps or one controller puts out 5 amps and the other zero?  Either way, at the prescribed 14.4 volts, or whatever you set it to, the battery bank will take 5 amps at that particular state of charge. 

You might want to run two separate cables from the two charge controllers to the battery.  The rise in voltage caused by one controller might have a strange effect on the other.  A shared minus side conductor would have little effect if it is the chassis.  Steel isn't the best conductor but the chassis is a huge conductor.  If your minus side is connected with wires I would suggest separate wires for that too.

 

[bonvanroulez]

Looking up a Santan 250 watt panel that they’re selling for $50, great deal, but it’s not a good match for a PWM charge controller. The Santan site says that panel makes its maximum power at 30.3 volts and 8.85 amps. Connecting that panel to a discharged battery through a PWM controller will pull the panel voltage down to battery voltage of say 12 volts so at 8.85 amps your battery will only be getting 106 watts from your 250 watt panel. Even approaching a higher bulk charge state of 14 volts at 8.85 will be 124 watts. So you will be generally using less than half of the 250 watt panels potential.

This is why MPPT controllers are considered a better match for higher voltage panels, and why a PWM controller, if desired, is better suited for use with a panel that makes its maximum power at a voltage closer to battery voltage like 16 or 17 volts.


This was the Santan 250 watt panel that came up in my search:
https://store.santansolar.com/product/santan-solar-t-series-250w/

 

[jimindenver]

I know nothing of this controller except that it seems to get good reviews. Since Renogy tends to relabel you might just find the same thing under a different name at a lower price.

As far as running the 250 watt panels from Santan. The controller will not take either the Santan 250 watt at 37.7 Voc or the SunPower 250 watt at 58.8 Voc because their Voc is too high. Even if the controller could accept the Voc's it would work at the voltage of the battery and shed anything above that. That means the Santan panel would lose 50% or more of the 8.27 amps of power it produces and in the case of the SunPower panel you would get about a fifth of the 5.8 amps that it produces at nearly 60 Volts or just over 1 amp from 250 watts of panel.

 

[XERTYX]

Excellent. Thank you for the timely feedback guys. And I know for a fact that you know what you're talking about.

I dont mind that the units are all made in china but I've had difficulties before with counterfeit knock off limitations before. My current charge controller was advertised as an MPPT in a kit I got with a flexible dual USB output solar panel that I was after in the first place but the manual is for a PWM so I assume it is a PWM controller. I'm using it with 4 matched 5 watt panels with a voc of 18.7 or 19.1 volts maybe.

When I built it with end of season deer feeder branded clearance batteries from a superstore. They are the same 7AH SLA alarm system batteries you can find all over amazon etc. The controller I've noticed has a different reading of actual volts when I first connected it and when it cycles to 12.6-12.5 volts or so. I dont tax the system and when its floating at 14.4 volts (I had the upper threshold at 14.2 volts initially to compensate for the inaccuracy and adjusted accordingly) but when it reads 14.4v on the controller the actual voltage is 14.4 .

So that controller would be best suited to ~$100 amazon 100 watt solar panels is my take away?

I'm on the east coast so shipping is a concern from gilbert Az as santan uses palletized freight shipping. But buying multiple panels would offset the cost differential considerably especially if I went in on shipping with a buddy.

So I should be looking into several amazon panels (18ish voc panels) and that controller or a pricier controller and santan panels?

 

[Weight]

Renogy is recognized company that is known for good enough quality. That is a small charge controller. Why not a Renogy kit from Amazon? Then you know your money was well spent. https://www.amazon.com/Renogy-Monoc...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

 

[XERTYX]

That is a pretty good deal I'd say for a prefab kit. I might go that route anyway.

I didnt want to bog down the sub forum with other charge controllers. Assuming I did want to go with $50 santan 250w panels with a voc of 37.6 would this renogy MPPT controller with a voc of 15-100v work? Its $160 for the controller and 2 $50 panels bringing the project to $260+ tax and shipping for 500 watts Vs that kit for $278 + tax free shipping with 200 watts. 

https://www.amazon.com/Renogy-RCC40RVRE-G1-Charge-Controller-Display/dp/B083BFYJJG

I'd like to have the higher watts for obvious reasons but also I want to incorporate using a 300w rice cooker intermittently possibly even daily especially on full sun days. I like to use it to boil eggs and sometimes making pasta. It makes half a dozen perfect hard boiled eggs in 20 minutes in my experiments.

I dont have a killawatt meter so I'm going off of the appliance specs but assuming it's a constant 300w (I'm sure its not) 300w used for 1/3 of an hour= 100wh (not taking the puekert effect into consideration) so still doable with 200w of panels but with 500w if it's a super sunny day it should just be surplus energy. So that other than adding an LCD tv and 12v compressor fridge at some point would be the bulk of my prospective battery usage.

I know recharging my phone and flashlight wouldnt be a problem. I'm currently running my phone AND flashlight entirely off of 20w of solar and I've never once failed to recharge the batteries to full even on cloudy days.

 

[1shemp]

You can get a good mppt (EPSolar) controller for less than $100 and use the 250 watt panel.Or buy a couple of 100 watt panels on Ebay and get free shipping.Good luck.

 

[XERTYX]

Welcome back XERTYX!

Thanks. I have been lurking a bit I just havent been posting.

I think I saw the EPsolar controller you are talking about but if I remember correctly it was a 20A. If I want 500 watts of solar I'd need the 40A or 2 20As.

I found a van in my price range yesterday. It's a painter van. Kinda ragged out and has a ladder rack already. I think I could fit the panels up there easily and since it's a little elevated maybe I could also fit a fantastic type fan on the roof as well. I'll have to see how the budget runs.

 

[wayne49]

Ladder racks don't have to be expensive.
Don't choose a "ragged out" van just because it already has a ladder rack.
Mechanically sound? The interior dimensions are what you need?

 

[XERTYX]

My ideal vehicle is a 2005 or newer dodge caravan or Chrysler town and country with stow n go seats. But this one is made as a work van and has more overhead and 2 fewer windows so. . . Meh. It'll do and it's what I can afford.

 

[barleyguy]

As has been discussed, IMO the best bang for the buck is the EPSolar/EPEver/Tracer MPPT controllers. Will Prowse has a video recommending them, and he's someone I tend to trust the opinion of.

If you want to go with the Santan panels, you could also buy the charge controller through them, which would put all your support through the same place. They have the 30A EPEver for $85.00:

https://store.santansolar.com/product/epever-3210-30a-mppt-solar-charge-controller/

EPEver also makes 40A versions, but Santan doesn't have them on their site.

 

[barleyguy]

Oh, while browsing for EPEver controllers on Santan, I noticed this:

https://store.santansolar.com/product/1-250w-solar-panel-kit/

It's a 250 watt poly panel, a 20A Tracer MPPT controller, cabling, z-brackets, and accessories for $165.00

You'd probably need to drive to Phoenix for it to be a good deal, because the poly panel probably needs freight shipping. But otherwise a smoking good deal IMO.