Solar Install, Reflection 29RS Fifth Wheel

[Jimmer]

Should I have a bigger solar controller?

Brian

I believe your MPPT Solar Controller can have a max input of 100 volts, and a max out of 30 amps. With two 200 watt solar panels, your max solar power is 400 watts. Assuming 100% efficiency in the MPPT (which it is not), you will have an output of 400 watts. For argument sake, let's say you run down your batteries and they are at 11.5 volts. If you have 400 watts of power going into the batteries at 11.5 volts, that means you will be charging with 400/11.5 = 34.8 amps. But your MPPT solar controller can only put out 30 amps, so you might be wasting/not using 4.8 amps of charging.

However, let's say the sun is rising in the morning and your panels are only putting out 300 watts to begin in the morning, your solar charge can get the voltage up to 14.4 volts (but still be in bulk charging mode). Then, you get some directly overhead sun, and the panels are putting out 400 watts. 400/14.4 = 27.8 amps. Thus, when your batteries are at 14.4 volts and the panels are putting out their max power of 400 watts, no energy is wasted.

It is my understanding with the Victron MPPTs, if you exceed their power capacity nothing bad happens to them and you're not going to hurt them. Bottom line is that you'll be losing a little of your solar power when the panels are at max output and your batteries are run down and below (400/30) 13.3 volts. This is going to be a rare/never occurrence so it's highly unlikely that you'll be losing much, if any, solar output.

I went through the same issue with my Victron dealer. I have fourteen 100 watt panels and a 150/100 Victron MPPT. 1400watts/14 volts = 100 amps. So, I'll be losing solar power when all 14 panels are pumping out their max power, and my batteries are below 14 volts. I'm not at all concerned about this.

[ncitro]

Boy with the other threads going on with the "serial, parallel" talk and the correct size of solar controller I am wondering if I made the right choice of solar controller size.

What I have is the Victron 100/30, here is a pic of the specs on the panels


I have 10 ga. wire from the panels to the combiner box, then 2 ga wire down to the solar controller, about 17 feet.

Should I have a bigger solar controller?

Brian

My understanding is your panel max current is 10A, and max voltage is 20.4 so if they are in parallel you would have 20A, and if they are in series you would have 40V, either way you are under the 100V 30A max of your controller.

[Country Campers]

Thanks guys. This solar stuff is still confusing even though the explanations make it easy to understand.

Brian

[Jimmer]

My understanding is your panel max current is 10A, and max voltage is 20.4 so if they are in parallel you would have 20A, and if they are in series you would have 40V, either way you are under the 100V 30A max of your controller.

Neil, your logic would be correct if both the 100/30 were for the input. But because the "30" of the controller name relates to output charging current, it's not as simple as looking at the output current of the panels which is the input current to the solar controller. But the answer is still the same in this case so it really doesn't matter (see my post #16 above). The controller is fine for his two 200 watt panels.

[ncitro]

Neil, your logic would be correct if both the 100/30 were for the input. But because the "30" of the controller name relates to output charging current, it's not as simple as looking at the output current of the panels which is the input current to the solar controller. But the answer is still the same in this case so it really doesn't matter (see my post #16 above). The controller is fine for his two 200 watt panels.

Sorry I missed your post, I think because it bumped to the next page. You are correct, I forgot the 30 is output. He is running Lion Energy lithium batteries, and they want a fixed 14.6v, so I think his max current is around 27 like you suggested. Obviously if he was going to add additional panels, those would need to go in series, for a 2S2P combo, but that should still be below the controllers max.

[Jimmer]

Sorry I missed your post, I think because it bumped to the next page. You are correct, I forgot the 30 is output. He is running Lion Energy lithium batteries, and they want a fixed 14.6v, so I think his max current is around 27 like you suggested. Obviously if he was going to add additional panels, those would need to go in series, for a 2S2P combo, but that should still be below the controllers max.

Yep, I thought I lost my post when it went over to the next page.

Note that his solar charger is pretty much maxed out with his 400 watts of solar, as it can only output 30 amps. Adding more panels in any configuration would require a second or larger solar charger as the output voltage is fixed by the batteries, and the output current of that controller is limited to 30amps.

[ncitro]

Yep, I thought I lost my post when it went over to the next page.

Note that his solar charger is pretty much maxed out with his 400 watts of solar, as it can only output 30 amps. Adding more panels in any configuration would require a second or larger solar charger as the output voltage is fixed by the batteries, and the output current of that controller is limited to 30amps.

I see what you are saying now. Since the current rating of the controller is based on the output it does not matter how the panels are wired. That makes sense.

So Country Campers , you will be fine but if you add more panels you either will need a bigger controller or will need to add a second one (which would be tricky with the way you ran your wiring). Personally unless you are adding more panels immediately I would stick with what you have, then upgrade and sell your 30A controller down the road.

[RV Tech Ret]

https://gdrvowners.com/member/6-country-campers

Country Camper...

Are you going to add an inverter to that awesome setup you have? Also, the battery disconnect on the positive side of the battery you have in the pic is that your standard 12 volt system disconnect on your Reflection or did you add that as part of your new system?

Working on my own system right now and learning all I can....

Mark

[RV Tech Ret]

Looks like I don't know how to tag someone....

[Country Campers]

RV Tech Ret

That is how you tag a member, add the @ in front of the member name and a pop up window will show up and you can pick the member.

I added a "true" battery disconnect, the one in the bottom of the picture, the one above is for disconnecting the solar array. I am thinking of a 2000 watt inverter but have not figured out what I want yet. We are thinking to use this system as is, we only have a few "off grid" campouts scheduled this year so far, and see how it works and if we want to upgrade sooner than later. I think if we decide to go "all in" and deep into the rabbit hole of solar we will go with a Victron Multiplus and a couple more batteries. I have tried to make this simple system easy to upgrade if we need to.

Brian

[Jimmer]

RV Tech Ret

... I am thinking of a 2000 watt inverter but have not figured out what I want yet. We are thinking to use this system as is, we only have a few "off grid" campouts scheduled this year so far, and see how it works and if we want to upgrade sooner than later. I think if we decide to go "all in" and deep into the rabbit hole of solar we will go with a Victron Multiplus and a couple more batteries. I have tried to make this simple system easy to upgrade if we need to.

Brian

Go with the Multiplus II now. You'll be happy you did. You'll find added benefits with it besides inverting. For example, on a recent trip to Sebastian Inlet State Park near Vero Beach in Florida, we had 30 amp electrical service. So, I dialed in the Multiplus to take no more than 30 amps. It was hot out and I had one AC running pretty much continuously. That uses about 16 amps out of the 30amps available. We were also using the microwave, electric refrigerator, and clothes washer/dryer during the trip, in addition to the electric water heater. There were many times that we exceeded using 30 amps, but the Multiplus used the batteries of the camper to supply the extra power. So, we basically did not have to ration the power or watch how much we were using. What a great convenience.

Plus, with the UPS (uninterruptable power supply) feature, you always have power, and don't have to worry about switching over from the inverter to campground power. Also, the touch screen interface is wicked cool!

[Country Campers]

Jimmer

This is the rabbit hole that I speak of. Although all of those items are great and I surely would like to go all in it just does not suit us at this time, maybe next winter.

Brian

[Bobsrv]

How did you wire you dc to dc charger from truck to trailer ?

[Country Campers]

How did you wire you dc to dc charger from truck to trailer ?

I just wired it from the stock wiring from the factory on the trailer. I am only using a 20 amp DC-DC so the truck wiring should handle it. I found the wiring in the front storage and removed the positive and negative and attached to the input on the DC-DC and then out put to the battery and shunt. I have not tested this yet as it has been winter but should work.


The input is on the right. The yellow wire is a switch that will turn on and off the charger, I wired the yellow wire to the trailer marker lights to signal the charger to be on when lights are on and off when lights are off. I always travel with the lights on so if I do not need the charger to be on I can turn it off with the switch. I will post a thread on this install and link to it.

Anything else you need please ask.

Brian

[Country Campers]

Here is the thread for the DC-DC Charger install DC-DC Charge install Reflection 29RS - Grand Design Owners Forums (gdrvowners.com)

Brian