Dual Battery Solar Panel Question

So I'm definitely adding a dual battery setup that supports solar panels. Currently I do not have anything the constantly runs off the truck but I have killed my battery a lot on camping trips and other extended trips. I prewired my roof rack for a solar panel, but what I am wondering right now is should I put a 50w or a 100w panel on the roof. A 50w fits better with the setup I'm looking to have and I could always wire an add on 100w panel to attach the top of the bed cover. Would it be worth the real estate on the roof to put a 100w up there or should I go with a 50w?

Thanks in advance for any feedback

 

You really need to sit down and do the math to calculate your needs. What kills your battery camping? Lights, fridge, heating blanket, radio...etc. Then determine the power draw required and for how long on average use, figure in a bit of loss through heat and then determine how large of a battery you have? Use amp/hour to keep it common. I have 3x100w in series on a 12V system to a 100amp/hour lithium batter. The solar inverter/charger can use grid power as well. It is divorced from the truck charging system. I keep a dual purpose 31 series truck battery and a Battleborn lithium with just solar to run fans, radio, lights, fridge, and diesel heater

 

Have you seen this hood mounted panel?

 

There was a shitshow of a thread about it awhile back. Neat idea, efficient use of space, but very high cost for the package setup. Very much like buying Goal Zero versus build your own. Convenience comes at a cost. I would probably use my hood but the skewp nullifies that idea.

 

Its definitely an interesting idea. I'm not sure I'd like the look on a cement truck... maybe if the truck was black.

 

Fair. I should definitely do that. I'm looking at going with 2 Odyssey PC1400 Group 35 batteries to pair with OffGrid Engineering's Redarc setupww. Right now most of the draining comes from lights, charging a ton of devices off the bed outlet, and speakers. More to be added in the future which is why I'm going to run extra wires.

 

Not trying to be an ass when answering but through my own trials I realized that I tried building the adventure rig without knowing what my own requirements were. I killed power setups, tripped fuses and the like. I tried to stack up as much wattage up top that I had space to hold. The battery you use will be more important than anything else since all you are doing are just topping it back off from utilization through the night. Battery size immaterial, I would recommend you give serious consideration to LiFePO4 chemistry for for stable solid power and better bang for buck per watt over any AGM.

 

What voltage are your panels? If 12V in series is 36V so I am wondering what kind of charge controller you are running. Mine are 2EA 12V/100W in parallel to a 12V controller because I want the current.

 

Voltage stays constant, only wattage totals in series. I am using a 12V system. MPP Solar PIP-812LV-MS

 

In a series circuit the voltage increases but the amperage stays the same (3 X 12V = 36V) Amperage is still 100W

In a parallel circuit the voltage stays the same but the amperage increases (3 X 100W = 300W) Voltage is still 12V

Since you have a 12V controller amperage at 12V is what you want to supply your battery bank as you use it.

 

My bad, 500w and 102V

The PV input for my controller inverter is 500W and 102V max. I’m sorry I got confused on the last question. I am storing and utilizing and 12V DC and 120 VAC setup off the controller.

 

Didnt think you were being an ass. I'm learning here and trying to do it right.

 

I was thinking smoke there for a minute and hoping I was misunderstanding something. I only noticed because last week a friend of mine got confused about the very same thing and fried his brand new controller. He was packing it back into the box thinking he was sent a defective one until he understood the difference.

BTW, always wanted to tinker with a diesel heater for a while. It being Louisiana here though....

 

I built the heater into a hardigg military case and mounted it in my trailer. I will get some pics tomorrow. Cool concept and way more efficient than electric heat or propane.

 

Cool idea. I’d like to see it.

I am lucky that I really don’t need an inverter as everything I need runs on 12V so I am more interested in long term power for only that. It’s an inbred hurricane thing I guess. Around here we generally need air conditioning way more than heaters! For that a small gen set makes way more sense than the loss that comes with an inverter.

 

The very first and most important step is to calculate what your consumption needs are in the first place. With 12V devices it is pretty easy to measure current draw with a multimeter. Just add up how much current everything you need to run draws, then multiply by how many hours you need them to run. That is a simple power budget. From that step you can realistically size a battery and charging system to fit. Doing it the other way around like many do doesn’t always work very well...

There is an online calculator that can help with the sizing numbers once you have made a budget - https://www.batterystuff.com/kb/tools/calculator-sizing-a-battery-to-a-load.html

 

Thanks for the advice. I'll see if can calculate what I need