Solar charging

[SurveyorStan]

Hello all. i am interested in adding solar to my tt to charge batteries when we don't have connection to electricity. We have a 28 foot tt and would only to need to run a standard rv refrigerator, a couple of LED lights, and occasionally the water pump. We can go 3-4 days on the two batteries we have, but would like to be able to keep the batteries charged while we are camped. We currently have two 12 volt deep cycle batteries that came with the unit when we bought it new. They are lead/acid. I'm looking at a Renogy 200 watt suitcase system so it can be portable. Those of you with solar experience, do you think 200 watts will do what i want?

Read this forum regularly and appreciate all the input!!

[TowPro]

If out in the middle of a field or beach, its a couple is sunny days. and you aim them 200w should work

[boondocking]

Yup, 200 watts should do you just fine.

[Mike134]

I like the ability with a suitcase to follow the sun if I'm in camp otherwise positioning it for the best average exposure/angle.

[NJKris]

Please provide a link for this 200W suitcase. I have a 100W Renogy. It's pretty large. I didn't know they made a 200W suitcase. It must be HUGE!

[boondocking]

Originally Posted by NJKris

Please provide a link for this 200W suitcase. I have a 100W Renogy. It's pretty large. I didn't know they made a 200W suitcase. It must be HUGE!

Renogy 200 watt suitcase
Unfolded - 36" x 52"
Folded up - 36" x 26"

[Hawkester]

https://www.renogy.com/200-watt-12-v...kaApIpEALw_wcB

This one isn't a suit case but a few quick cheap mods and it could be.

[acadianbob]

We are using a 130 Watt Go Power "suitcase" system that we purchased through etrailer. It puts out about 6.7 amps under full sun. Plenty to keep us topped off; at least until the amount of sunlight diminishes in the fall. Then some generator time is required; less sun, more lights, occasional furnace blower. We also use the generator at breakfast and at dinner for the microwave; hair dryer; etc. that require 110V. We have a residential refrigerator that runs off of an inverter.

The Go Power system comes with an adapter that plugs right into the Furrion solar plug with which so many Forest River products are equipped. Most of these pre-wired plugs are rated at 10 amps (and sometimes with a 7.5 amp fuse). So, a system much bigger than 130 watt would require a different approach/connection.

We are clearly solar light-weights but this works for us. We have two Group 27 12V AGM batteries. Total of 185 amp hrs.

[SurveyorStan]

Originally Posted by acadianbob

We are using a 130 Watt Go Power "suitcase" system that we purchased through etrailer. It puts out about 6.7 amps under full sun. Plenty to keep us topped off; at least until the amount of sunlight diminishes in the fall. Then some generator time is required; less sun, more lights, occasional furnace blower. We also use the generator at breakfast and at dinner for the microwave; hair dryer; etc. that require 110V. We have a residential refrigerator that runs off of an inverter.

The Go Power system comes with an adapter that plugs right into the Furrion solar plug with which so many Forest River products are equipped. Most of these pre-wired plugs are rated at 10 amps (and sometimes with a 7.5 amp fuse). So, a system much bigger than 130 watt would require a different approach/connection.

We are clearly solar light-weights but this works for us. We have two Group 27 12V AGM batteries. Total of 185 amp hrs.

So, AcadianBob, do you think the 100 watt system would be OK?

[Flybob]

If you can keep the panels in the sun a good part of the day you should be OK. Just as a clarification, your batteries are most likely dual purpose batteries and not deep cycle. The batteries usually provided by dealers are marine dual purpose batteries. If you boondock often you may want to look at real deep cycle batteries.

[SurveyorStan]

Originally Posted by boondocking

Yup, 200 watts should do you just fine.

Thanks for the help boondocking! Do you think the 100 watt system would be enough, or is 200 watts what I need? I'm looking to get answers on sizing this from someone who has used solar. Thanks again

[Flybob]

Most people underestimate their needs. It is usually less expensive to purchase a 200W system than two 100W systems. Remember you could have 3-4 cloudy rainy days with poor charging.

[TitanMike]

Originally Posted by SurveyorStan

Thanks for the help boondocking! Do you think the 100 watt system would be enough, or is 200 watts what I need? I'm looking to get answers on sizing this from someone who has used solar. Thanks again

The reality is that it's all going to depend on the amount of power consumed by the refrigerator. I have a 160 watt "suitcase" that I've modified to feed an MPPT controller (for increased efficiency). It keeps up with the power drawn by my small freezer that I replaced outside kitchen's refrigerator with as well as all the rest of my power use.

Because I use ALL of the power generated by the panels with the MPPT controller, and can move the panels around for max output, 160 watts is more than enough. For others with larger refrigerators and other power draws, 200 watts may be too small especially if panels can't be moved for max output.

[TowPro]

Or by PWM over Mppt and the money saved will by an extra 100w panel and you will be ahead of the game.


Small exert below from Bogart Engineering


The “good” for PWM: It is simpler and lower cost technology. Under some common circumstances–it can actually deliver more amps to the battery. That could be when:
(1)days are moderate or warm, with few clouds. (sounds like when I camp)

(2) batteries are charging at over 13 volts, (in a 12 battery system) which they almost always are when actually CHARGING.
(3) Panel voltage is properly matched to the battery voltage, for example “12V” panels are being used with a 12V system.
PWM is actually more “power efficient” than MPPT–which means less total power loss in the controller itself. So heat sinks in the design can be smaller (and less expensive). Missing in most analysis of MPPT is that there is always a conversion loss with MPPT, which tends to be higher the greater the voltage difference between battery and panels. That’s why PWM can actually beat MPPT under circumstances described above.

[SurveyorStan]

Originally Posted by TowPro

Or by PWM over Mppt and the money saved will by an extra 100w panel and you will be ahead of the game.


Small exert below from Bogart Engineering


The “good” for PWM: It is simpler and lower cost technology. Under some common circumstances–it can actually deliver more amps to the battery. That could be when:
(1)days are moderate or warm, with few clouds. (sounds like when I camp)

(2) batteries are charging at over 13 volts, (in a 12 battery system) which they almost always are when actually CHARGING.
(3) Panel voltage is properly matched to the battery voltage, for example “12V” panels are being used with a 12V system.
PWM is actually more “power efficient” than MPPT–which means less total power loss in the controller itself. So heat sinks in the design can be smaller (and less expensive). Missing in most analysis of MPPT is that there is always a conversion loss with MPPT, which tends to be higher the greater the voltage difference between battery and panels. That’s why PWM can actually beat MPPT under circumstances described above.

TowPro, good information. Thanks for your input.

[babock]

Originally Posted by SurveyorStan

So, AcadianBob, do you think the 100 watt system would be OK?

They are going to give you 5 to 6A if aimed perfectly. For a 5 hour equivalent sun day, that's only 25AH to 30AH.

[Chewman]

Hello, I'm new to RV trailers.
I bought a 2020 Geo Pro 19FD and I have the following questions:
When the inverter is turned off do the solar panels still charge the battery?

Does the inverter only convert DC to AC current for the outlets in the trailer?
Thank you!

[babock]

Originally Posted by TowPro

Or by PWM over Mppt and the money saved will by an extra 100w panel and you will be ahead of the game.


Small exert below from Bogart Engineering


The “good” for PWM: It is simpler and lower cost technology. Under some common circumstances–it can actually deliver more amps to the battery. That could be when:
(1)days are moderate or warm, with few clouds. (sounds like when I camp)

(2) batteries are charging at over 13 volts, (in a 12 battery system) which they almost always are when actually CHARGING.
(3) Panel voltage is properly matched to the battery voltage, for example “12V” panels are being used with a 12V system.
PWM is actually more “power efficient” than MPPT–which means less total power loss in the controller itself. So heat sinks in the design can be smaller (and less expensive). Missing in most analysis of MPPT is that there is always a conversion loss with MPPT, which tends to be higher the greater the voltage difference between battery and panels. That’s why PWM can actually beat MPPT under circumstances described above.

Yeah...Bogart is basically selling out of date products so of course they will say this. Bogart has been sold and the new owners have no intention of ever updating their products. They can't compete. Even if they develop an MPPT they can't compete with the Chinese MPPT or even Victron controllers. Victron controllers are 98% efficient. You can actually do the calculation yourself by looking at the input power from the solar panel to the voltage and current delivered to the battery.

PWM more efficient than MPPT? LOL

PWM controllers can only deliver the current that the panel puts out. Any voltage difference between the battery charge voltage and the panel voltage is wasted.

[boondocking]

Originally Posted by SurveyorStan

Thanks for the help boondocking! Do you think the 100 watt system would be enough, or is 200 watts what I need? I'm looking to get answers on sizing this from someone who has used solar. Thanks again

To give you some idea I do not have a TV or residential fridge, have led lighting, use water pump and charge drone batteries and laptop. My batteries (230 ah) are usually at about 70-75 % charge in the morning and are fully charged by mid afternoon.

I would suggest going with 200 watt, you will be much happier with your set up.

[SurveyorStan]

Originally Posted by boondocking

To give you some idea I do not have a TV or residential fridge, have led lighting, use water pump and charge drone batteries and laptop. My batteries (230 ah) are usually at about 70-75 % charge in the morning and are fully charged by mid afternoon.

I would suggest going with 200 watt, you will be much happier with your set up.

Boondocking, thanks. That's what I was originally thinking to do. I think that's the plan!