Recommendations for solar charge/controller

[jodeb720]

It appears a buddy of mind is going to donate two used 300 watt panels.

They are rated at 30 volts with about 8 amps open voltage (he got them for a song - used I should say)

We’ve been out in the desert in socal and after wiring in a progressive dynamics charger, a 2000 watt psw inverter and a midnight 150 charge controller we are pretty happy with the results.

Since he bought 6 and needs only 4, they are going to be donated to me.

Questions:

1. How many amps should I size tge controller at?
2. PWM or MPPT?
3 Any brand you’d recommend.

Im running 420 amps (2-battery banks GC4 so two 210 banks)
I generally charge the separately (my house batteries are from July 2014 and they are still going strong!) , the other bank feeds my 1000 psw inverter for coffee.

Thanks in advance….

[MrWizard]

Suggestion
Get a DC marine type circuit breaker, 50 amp is good 100 amp would be better, place in circuit between the panels and the solar charger controller, then whenever you need to switch battery Banks, or any kind of battery service , you can easily open the circuit , safely disconnecting the panels, preventing damage to the controller, I also installed a DC breaker between my batteries and my 2000w psw inverter, that one is rated at 250 amps

[pianotuna]

Plugs are indeed pretty fool proof. I use them on the 120 side of my system.
One female outlet the generator, one for shore power and another for a 30 amp connection at the front of the RV (30 amp male).

My charge controller tolerates have no "load" from the batteries. I don't make a practise of doing so. I pretty much have the batteries connected 24/7/365 to the charge controller.

[Boomerweps]

Several battery disconnects are set up with a battery 1, 2, 1+2, and off positions. If used to seperate battery banks, a pre controller panel disconnect switch should be added to use while shifting battery banks.
My hillbilly engineering degree method is that I have an SAE/Zamp style side connection from the panels and another similar inside from that jack that I can easily disconnect. The interior one is handy if I want to connect the stand alone charger. Switches are great but unplugging works just as easy.

[pianotuna]

Since the batteries need to stay connected to the charge controller the correct way to do so is to turn on the 2nd bank, and then turn off the first bank.

Some controllers don't care about this. Other controllers may fail if the panels are connected but the batteries are not.

I much prefer having a voltage sensitive solenoid to "add" the 2nd bank.

I added additional switches so I can charge one bank while using the other.

[StirCrazy]

jodeb720 wrote:


Will a sudden disconnect and reconnect from bank to bank cause a failure?

Do I need to disconnect the feed from the Panels first to the controller, then switch over, then reconnect the feed from the panels?


Thanks so much!!

it can and yes.

add a switch between the panels and charge controller also, that is handy to have anyways and should be on every installation so you can just turn off the panels if you want to work on something. I used manual resettable breakers for mine, so they act as a proper breaker also but I can manulay trip them when I want the panels off.

[Boomerweps]

If going to the effort of having switch to switch between battery banks, adding another between the panels and controller shouldn’t be a big deal.
Every controller manual emphasizes connecting the batteries first and disconnecting them last. They imply damage may occur but not stated clearly how. IMO, there is concern about the battery not powering the control circuitry and the panel power not being limited.
You could always shift banks at night 😉

[pianotuna]

jodeb720,

Manual switching is possible.

There are alternatives such as a voltage sensitive solenoid that would 'add' the second bank when voltage reaches 13.5.

[jodeb720]

this is all excellent advice -
One question though. Can I manually switch the controller from bank 1 to bank 2?

As I stated, I run my batteries through a marine switch - which feeds from bank 1 or bank 2 or both. I have them separated because of the age difference of the batteries and use. Bank 1 serves the RV House needs (water pump, fans, lights) and Bank 2 serves my Inverter. I currently have two separate chargers which I run off my generator to bounce them back to 80% or more.

If I have my solar setup, will I be able to focus all the amps on Bank1 until it reaches 80% and then switch it to bank 2?

If so, I can use a mechanical switch (as I have for the source of power in the trailer), but what impact will a mechanical switch have for designating the destination of the charging on the controller?

Will a sudden disconnect and reconnect from bank to bank cause a failure?

Do I need to disconnect the feed from the Panels first to the controller, then switch over, then reconnect the feed from the panels?

i know this would be a lot easier if I just had one battery bank of 420 amps. Hence, I'm asking the questions before I let the blue magic smoke out of charge controller prematurely! 🙂

Thanks so much!!

[pianotuna]

Don't buy a controller for just the two panels. You may want, some time in the future to increase the harvest.

[deltabravo]

Victron MPPT

[Boomerweps]

If you have ANY shading on your panels in series, you will lose a lot of power. The gain in series is two fold from the higher voltage. One, the panel voltage reaches the activation voltage needed by the MPPT controller earlier in the day and retains it longer in the evening. The higher voltage allows more power flow through thinner wires, I.e., less line loss.
Starting in parallel allows you to easily add more panels.
IMO, EPEver controllers are the most cost effective. Victron is likely the best consumer grade units with a matching cost.
Wattage equals volts times amps. Which unit you need comes down to that. Easier still, find likely candidate controllers, download their manuals. The ones I’ve seen all state the recommended maximum PV wattage input. For example mine states 390watts at 12vdc. So I’m planning on ending up with four 100 watt panels since PV panels rarely put out their rated output (for many reasons).
I agree that you would want a 50 Amp capable unit. The EPEver tracer series 4210AN (40 amp unit) lists max PV wattage at 520 watts.

[Bobbo]

You are right. He is only receiving 2 panels, not 3. I misremembered from the first of the thread where he said the buddy got 6 panels, but only used 4, so is giving away 2. I will edit my original post.

[StirCrazy]

Bobbo wrote:
since the VOC is 45.29v, be sure that the MPPT controller is good to at least 150v.

Um.. all you need is one rated for 100V150 v is way overkill unless your running three panels.

[jodeb720]

My plane is to run 8 gauge wiring from the panels to tge controller and 2 or 4 gauge from tge controller to the battery. The biggest challenge is distance from the panels to the controller - I’m guessing 24’ conservatively.

We had one of the panel at a 75 degree to the sun (I’m currently in eastern San Diego county desert region. We were getting about 190 watts in the mid morning to noon sun, but tge controller was putting out about 15-18 amps to the battery bank.

It was impressive!