2 @295 watt panels in parallel

[MotorVation]

I'm getting ready to pull the trigger on two of these mono panels. I have an extended van. It may be tight getting a fan up there also but I think I can make it work.
I'm wondering if there's anything I'm overlooking. I'll pick up a 40 amp MPPT controller and will have 4, 6 volt FLA batteries for 470ah.

I would like to wire them in parallel to reduce shading issues.

The price is right on the panels and right now they're on sale for an additional 5% off. Even with paying freight it will come out to less than $1.00 a watt.
I have to work tonight so I won't be able to reply to anyone for a few hours. Thank you.

This link is for the panels I'm considering.

https://www.solar-electric.com/axitec-ac-295m-156-60s-monocrystalline-solar-panel.html

 

[jimindenver]

Wow Way to go! A solar system is born.

What controller are you looking at?

 

[Wabbit]

Did you see that 235w down in market forum?

 

[highdesertranger]

I like that panel. 2 of those will give you some kick. highdesertranger

 

[frater secessus]

Looks good to me.

The only limitation of 60cell panels is you might not have enough voltage to run a 24v battery bank with the panels in parallel. . But judging from your battery bank description you will be running 12v (2s2p) so it won't matter.

 

[Canine]

If won't be in Arizona to pick them up, shipping will cost you at least $130 for a grand total of $514. That is still less than a dollar a watt, so that is still a good deal. Something to be aware of.

Just because an MPPT controller is rated at 40 amps doesn't mean it will be able to handle both of those specific panels at the same time. Having that much solar will require a relatively large controller or two smaller ones. Two smaller, networked ones work better than one large one, but it could be a tad more expensive than one large charge controller. Something else to keep in mind. Do you have a specific controller in mind? That would help.

 

[MotorVation]

shipping will cost you at least $130 for a grand total of $514. That is still less than a dollar a watt, so that is still a good deal. Something to be aware of.

Just because an MPPT controller is rated at 40 amps doesn't mean it will be able to handle both of those specific panels at the same time. Having that much solar will require a relatively large controller or two smaller ones. Two smaller, networked ones work better than one large one, but it could be a tad more expensive than one large charge controller. Something else to keep in mind. Do you have a specific controller in mind? That would help.

Yes, I have to have them shipped by freight to me here in Florida. Comes out to about 535.00 total.
I was considering a brand x 400 watt kit for a while but I think I'll get more bang for the buck going this route and I won't have to worry about running out of battery.
I'm all ears on the controller. Money is definitely an issue so I would like to have only one. I'm looking at the 200.00 jobs such as the Renogy but half the reason I posted about the panels is because I don't want to buy the wrong one.
Thanks..

 

[MotorVation]

Wow Way to go! A solar system is born.

What controller are you looking at?

Jim, I don't really know aside from thinking I need a 40 amp MPPT. I do know I don't want to buy the wrong one. Money is a concern but I don't want to throw the cash down the toilet either..

Thanks....

 

[Canine]

When you look at the controller, you need to look at three things.

1) Amps. What is the total amps that the controller can handle? Yours is 40, so you are good there. Make sure that isn't 40 amps output, because that is different than the amount of amps that can come in from the solar panels. It also matters if the the panels are 36 cell or 60/72 cell. It also matters if the battery bank is 12 volt or 24 volt. Make sure you are looking in the 12 volt battery bank column when looking at the specs of the controller. My controller can handle 12 amps from the solar panel(s) with a 12 volt battery bank. It can handle more amps from the solar panels when the battery bank is 24 volts, so that can be confusing. Also, use the short circuit current or simply look for the highest number for amps (also referred to as current).

2) Volts. Look at the VOC rating. Or you can look for the highest voltage number. Make sure that number is lower than what the controller is rated to handle.

3) Total panel wattage. Add all of the watts together which in your case is 590 watts then compare that to the charge controller's maximum pv power (wattage).

Using one of my 3024i controllers with both of your solar panels in parallel as an example, it can't handle the amps (19.5 amps). It can handle the volts (39.95 voc). It can't handle the total watts. The limit for watts for the 3024i is 400 watts with 60 cell or 72 cell panels. If you were using 36 cell panels in parallel then it could go up to 540 watts worth of solar panels.


That may a bit overwhelming, but it is important to know so you don't tax your controller to the point of failure. If you want to connect your panels in parallel and use only one charge controller, Blue Sky Energy is out. If you are willing to go with two controllers (one for each panel), then that is an absolute minimum of $620. You will also need more wire, a switch, fuse, etc. The only controller that will work for you is the 3024i even if you used only one panel. One 295 watt solar panel is too powerful for any of the other controllers.

You can apply this knowledge to know which brands (Outback, Midnite, Victron, Morningstar, etc.) will work for your set up.

 

[frater secessus]

Just because an MPPT controller is rated at 40 amps doesn't mean it will be able to handle both of those specific panels at the same time. Having that much solar will require a relatively large controller or two smaller ones.

MPPT controllers are able to "clamp" power to their limit by increasing Vpanel (therefore reducing current);  this is not always implemented.  I am comfortable overpaneling a 40A MPPT controller to handle OP's planned mono unless the controller manufacturer says not to. 

Both the 40A Renogy Commander (rebranded epsolar 4215BN) and 40A Renogy Rover MPPT (maybe based on the 4215A?) clamp overcurrent as documented in their respective manuals.  I am not familiar with any other 40A MPPT controllers they have.

In this thread OP is talking about 590w on a 40A controller.  My setup is 570w on the abovementioned 40A 4215BN and performs very well, and at a Cheap (RV Living)  $200 price point.

 

[John61CT]

One SC per panel would be ideal if you anticipate any partial shading conditions:

https://baymarinesupply.com/victron-smartsolar-mppt-100-20-charge-controller.html

If you wanted both going through the same controller, you'd need to step up to their 100/50 model, less effective if shaded and a bit more expensive than two of the above.

 

[jimindenver]

Just because an MPPT controller is rated at 40 amps doesn't mean it will be able to handle both of those specific panels at the same time.

HUH say what?

40 amps is 40 amps. As long as the controller is rated to handle the Voc there isn't going to be any issues. A limited amount of headroom in Voc can be a issue if you go over a high altitude pass on a cold clear day but flat mounted those two will be lucky to see 40 amps and even if it did over produce the controller would simply clip the excess. That is called over paneling.

Were it a true issue a $478  Morningstar TS-MPPT-45 would give you any headroom you needed. It doesn't need the $125 remote meter but it makes it nice to know what's going on. Then again a serial to USB cord will let you see and do more than most any other controller.

I have a Renogy Rover 40 amp MPPT that may be a option but I have not had time to hook it up to the big panel on the truck as a mobile charging station to put it through any test.

 

[John61CT]

Xantrex C40, cheaper because PWM, lose a bit of efficiency.

But very robust, been around forever, have "diversion" load capability built-in (frater's opportunity), and quite adjustable charge setpoints.

https://www.altestore.com/store/cha...40-solar-charge-controller-40a-122448v-p2070/

 

[John61CT]

a $478  Morningstar TS-MPPT-45 would give you any headroom you needed.

If were spending that money,

Midnight Classic 250 plus WhizBang Jr, or

Blue Sky 3024i with IPN-Remote

incorporate shunt-based Battery Monitoring so end Absorb can be based directly on trailing amps acceptance rate.

Edit: yes that Blue Sky limitation with the different panel types is frustrating, they really have a limited range in their line, compared to Victron anyway.

Sometimes the best approach seems to be to decide on the controllers first, the shop for the panels that deliver best bang for the buck within that context.

But then with a smaller roof space you really should maximize the watts output that will fit those dimensions. . .

 

[John61CT]

It is true that many brands and sources at the cheaper end of the market flat-out lie wrt their specs, even claim MPPT falsely etc.

Cheap Chinese junk off eBay is a roll of the dice, unless a specific listing is recommended by someone with knowledge you trust that's verified its performance with an ammeter.

 

[jimindenver]

If were spending that money,

Midnight Classic 250 plus WhizBang Jr, or

Blue Sky 3024i with IPN-Remote

incorporate shunt-based Battery Monitoring so end Absorb can be based directly on trailing amps acceptance rate.

And which of these are on YOUR system John? The Blue Sky 3024i is a 30 amp. the Midnight Classic 250 is $802 and that doesn't include the WhizBang jr.

 

[sushidog]

I vote for the Morningstar TS-MPPT-45. I'm planning on using it on a high voltage 2,000-2,100 watt system with a 48v battery bank (to run a super high efficiency 48v dc mini-split heat pump.) It will handle up to 2,400 watts at 48v and 150 open circuit volts from your panels. Plus at 99% peak efficiency it's one of the most highly rated quality controllers out there with a long history of reliability backed by a 5 yr warranty.

Chip

 

[jimindenver]

To add

The heat sink on the Morningstar dissipates heat much better than the hard shell of the Victron. It does make it bigger but nothing like the Midnight Classic 250 which is huge. It has no fan to suck dust into your controller, make noise and fail on the rough conditions out here.

I have worked with the bluetooth on the Victron. What I can do and see on it is a pittance compared to the same on a Mornigstar. I can custom set absorption time to depth of discharge to get those trailing amps, even adjust the temperature compensation to match my banks guidelines. I can see the controller work in real time right down to watching it track the power point. I even know if my panels are dirty because it shows me what they are bringing down, again in real time.

 

[MotorVation]

I appreciate everyone's input so far. Thanks. I have to do that 4 letter word thingy (work) again tonight so
i can't stay online very long right now. In the meantime I'll try to digest the info..

 

[John61CT]

Also the Morningstar TS-MPPT is on a very short list of units that let you set Float to "just stop".

Some of the better battery systems last longer that way, and maybe in future you'll want one.