Help Me On My Trailer Solar Setup

[Semi-Hex]

(Thats just me, Sunshine is illegal where I live. We have to get by on what gets smuggled in on occasion.).

What's the going rate for Black market sunshine now a days?

 

[4x4junkie]

To a guy of low understanding, This above comment maybe not phrased well.
Those 250w module & charge controller will work just fine. MPPT is not required.
But the "problem" is that 250w module can provide far more energy than the PWM charge controller can capture & put to use. If one views unused energy as "wasted" or not is just opinion.
Btw, Its all moot point if the batteries are already charged and no loads exist on the system.
All the sunlight available wont be collected at all !

If the price of that 250W is a 'screaming deal', I suggest using it if your rooftop has room.
Within reason, I think one cant have enough solar collection capacity. (Thats just me, Sunshine is illegal where I live. We have to get by on what gets smuggled in on occasion.)
You can always change to MPPT later on if needs increase & find a PWM is not keeping up with demand.

The key word was "effectively"

Yes, it will work, but why purchase a big giant heavy panel to put on your roof that does what a much smaller & lighter panel can do? If you aren't going to harness that panel's full capability, then there little purpose in getting it over a smaller panel with the correct output voltage (it would be different if that panel were a freebie, though I'd still say the $$$ spent on a suitable controller would be worth it).

 

[dakota123]

Alright so from my understanding this is what i need and how to make this work. Keep in mind this is my first time ever doing this. Is this looking right?

 

[dakota123]

Thats pretty good. It will be fine if the current demand of your inverter is within capacity of that fuseholder.

Would it make more sense to wire it directly off of the battery?

 

[dakota123]

Yes. Connect the inverter directly to battery using an appropriate size fuse or circuitbreaker.
( OCPD in electro-speak.. Overcurrent Protection Device )

Just saw your edit haha I will do that. Not sure if I'm going to need the 1000watts most likely going to go to 400 range i just need it to charge my laptop and my DSLR batteries. does it matter how far away from the battery it is? In other words can i mount the inverter up in my RTT and just run the wires to the battery?

 

[4x4junkie]

Just saw your edit haha I will do that. Not sure if I'm going to need the 1000watts most likely going to go to 400 range i just need it to charge my laptop and my DSLR batteries. does it matter how far away from the battery it is? In other words can i mount the inverter up in my RTT and just run the wires to the battery?

The cables from the battery to the inverter would have to be very thick gauge so that you don't have too much voltage drop to where the inverter would kick off under load. You'd be better off running a 120V extension cord from the inverter up to your RTT.

Yes a 400W or maybe even as little as a 150W inverter should work to charge devices such as a laptop and/or camera batteries (check the combined power consumption rating of all the chargers/devices you think you might use simultaneously so you know what size inverter to get).

Also, I'd go with 120W minimum on the solar panel if trying to keep some capacity for a future fridge, but that's just me.

 

[teotwaki]

The key word was "effectively"

Yes, it will work, but why purchase a big giant heavy panel to put on your roof that does what a much smaller & lighter panel can do? If you aren't going to harness that panel's full capability, then there little purpose in getting it over a smaller panel with the correct output voltage (it would be different if that panel were a freebie, though I'd still say the $$$ spent on a suitable controller would be worth it).

One reason that a larger panel is useful is that we cannot always have perfect alignment and perfect sunshine and expect the full panel rating to be achieved all day long. If the system needs 100W of solar power to function during a normal day then going larger on the panel is better so as to avoid constant re-pointing of the panel or lower output on cloudy days. Also be aware of the panel's efficiency rating as a better rating means the power can be produced with less surface area than a panel with a lower efficiency rating.

 

[offroadtreks]

You need to build in some safeties in your specs. My setup might be over kill as I have 805 watts of solar and 400aH of lithium batteries.

But you are going to want a breaker between your controller and battery. I'd also suggest a proper bus fuse for the inverter and a master on/off and on/off for the solar before the charge controller.

Here is how mine is setup

A few other points, you get what you pay for with solar, especially when it comes to controllers and panels. You might want to add a nice monitor to your system, like one from Trimeteric. A friend had a Renology kit, and his pathetic display didn't give him much beyond current voltage.

 

[dakota123]

Thanks again guys for all the info.

Mickey what size circuit breaker should i get?

I have no idea what a bus fuse is and when i looked it up i don't understand how exactly it works.

Also, not sure what the purpose would be for an on/off switch between the solar and controller. Doesn't it stop sending power on its own when the battery is topped off? I feel like it would be a waste of money and I am trying to keep this as cheap as possible.

 

[calicamper]

Treat the inverter as a stand alone system fuse between inverter and battery. Done

Treat the solar system as its own system, controller, battery and solar panel. Done - if you want to power simple small stuff as you had described you can power your simple fuse box from the output side of the controller, thus use the controller to monitor battery use on the small items etc. Yes the controllers manage your battery. Only reason to add a cut off switch between the controller and battery, is for your idea of knowing everything is shut off. For sure a simple fuse between the battery and controller, and the inverter is just smart thinking to avoid a failure and possible issues carried all the way back to the battery.

I have a super cheap inverter on my boat. Forgot about that one. Its on 8guage wire and fused its direct connect to my battery. Its used for laptops. Bought it at costco few yrs back $115 I think. Again cheap not fancy but it handles the simple laptop needs just fine. It also displays the load, battery level and has a cut off feature.

 

[offroadtreks]

Thanks again guys for all the info.

Mickey what size circuit breaker should i get?

I have no idea what a bus fuse is and when i looked it up i don't understand how exactly it works.

Also, not sure what the purpose would be for an on/off switch between the solar and controller. Doesn't it stop sending power on its own when the battery is topped off? I feel like it would be a waste of money and I am trying to keep this as cheap as possible.

Just Mike.

Yes, the controller will stop charging. You can skip this one on the solar. I would consider it an option if you need to work on or have a reason to interrupt the power from the panels to the controller for whatever reason or emergency.

As long as you have the breaker though, if the controller fails or something happens, the breaker will trip and it won't keep sending power into the system. You probably won't need more than 30 Amps. Search Blue Sea Systems 285-Series Surface Mount 30A Circuit Breaker - depends on how many amps you expect your charging system to actually send out. My ground deploy can do 25 amps, so I have a 30 amp there and the other one is rated at 40 amps thus I have a 50 amp one. Because anything more would be an indicator that something is wrong with the system, like really wrong.

For the inverter, I am calling it the wrong thing: this is what I'm talking about
Blue Sea Systems ANL Fuse Block with Insulating Cover - 35 - 300A
Blue Sea Systems 5133 300A ANL Fuse

Depending on the size of your inverter there you can go even bigger or smaller on the Fuse block and the fuse. Just depends on the amperage you expect.

I added these up including 1 mini-knob all Blue Sea on Amazon, about $112.00 worth of cost. You could replace the components with cheaper brand.

For me though, the breaker and a master on/off would be the must haves of the system.

 

[LandCruiserPhil]

Using a breaker verses a fuse have a few benefits -
One time purchase
Easy to disconnect the power
No need to carry spare fuses.
Easier to trouble shoot to determine if you have a fault or overload

 

[4x4junkie]

One reason that a larger panel is useful is that we cannot always have perfect alignment and perfect sunshine and expect the full panel rating to be achieved all day long. If the system needs 100W of solar power to function during a normal day then going larger on the panel is better so as to avoid constant re-pointing of the panel or lower output on cloudy days. Also be aware of the panel's efficiency rating as a better rating means the power can be produced with less surface area than a panel with a lower efficiency rating.

I completely agree. What I'm referring to though is use of a 30 Vmp panel (rated for a 24V system) with a PWM controller on a 12V system. Under ANY conditions (full-sun, cloudiness, direct angle-of -incidence, less-than-ideal angle of incidence, etc.), about 55-60% of that panel's output potential will always be lost.
With a 17.5 Vmp panel, only about 10-20% will be lost.
This means you can get the same charging performance with a much smaller & lighter 150W-rated panel as with the 285W panel linked in the OP when using a PWM controller.

Alternatively, if the OP gets a MPPT controller (keeping the 285W panel), this will increase the current into the battery by about 2½× in full sun, and more than 3× under cloudy conditions (unlike a PWM unit, it is able to convert the panel voltage to harness the panel's full output potential).

 

[teotwaki]

I completely agree. What I'm referring to though is use of a 30 Vmp panel (rated for a 24V system) with a PWM controller on a 12V system. Under ANY conditions (full-sun, cloudiness, direct angle-of -incidence, less-than-ideal angle of incidence, etc.), about 55-60% of that panel's output potential will always be lost.
With a 17.5 Vmp panel, only about 10-20% will be lost.
This means you can get the same charging performance with a much smaller & lighter 150W-rated panel as with the 285W panel linked in the OP when using a PWM controller.

Alternatively, if the OP gets a MPPT controller (keeping the 285W panel), this will increase the current into the battery by about 2½× in full sun, and more than 3× under cloudy conditions (unlike a PWM unit, it is able to convert the panel voltage to harness the panel's full output potential).

Okay, I agree a 24 volt panel is not a great choice but I was going by the 80 watt panel that was offered up by the OP on pages 3 & 4 that tops out at 21 volts.

Manufacturer: Solar Cynergy
Cells: Q-Cells
Max Power: 80 W
Open Circuit Voltage (Voc): 21.0V
Short Circuit Current (Isc): 5.36A
Optimum Operating Current (Imp): 4.65A
Optimum Operating Volatage (Vmp): 17.0V

Dimensions (inches): 33.35 x 25.97 x 1.33

 

[offroadtreks]

Okay, I agree a 24 volt panel is not a great choice but I was going by the 80 watt panel that was offered up by the OP on pages 3 & 4 that tops out at 21 volts.

Manufacturer: Solar Cynergy
Cells: Q-Cells
Max Power: 80 W
Open Circuit Voltage (Voc): 21.0V
Short Circuit Current (Isc): 5.36A
Optimum Operating Current (Imp): 4.65A
Optimum Operating Volatage (Vmp): 17.0V

Dimensions (inches): 33.35 x 25.97 x 1.33

Rule of thumb, Imp & Vmp - VOC is only ever going to happen in a lab.