Solar Build for Travel Trailer - Requesting Help

[Mattb4]

What is the results of the energy audit you did? Understand that using solar/battery versus grid or generator that ratings are not what you actually get. You need to allow for all the losses. So as example your energy audit shows need of 500wh per day. Your system will likely need to be able to develop at least 3-4 times that in order to account for losses, loads and return to a state where you can start the next day without being already partially depleted. Thus 1500 to 2000wh. Does your design incorporate all of this? If not than every day you have to subtract from your battery the amount you do not meet full restore capacity from solar. This will give you run time until a generator or shore power becomes available.

A 206ah 12v battery is able to deliver 10.3 amps for 20 hours before completely discharged (10.3 *12= 123.6 watts per hour for 20 hours). Or it can deliver ~2400 watts in 1 hour before dead.

ETA: There is also one other factor that I forgot to mention. Your panels might be sufficient to recharge your battery and supply loads during the peak of the day. However any additional power they could supply is lost once your batteries become charged. The panels no longer see the battery as loads. Amount of storage and amount of generation for loads is a strange dynamic.

 

[TravelingSLO]

This comment is so incredibly helpful. Thank you for taking the time to write it. I knew there was some loss, but I didn't know these specifics. I recognize that the information is out there, but sequencing it all into something that makes sense to me is proving to be the difficult part. How do people learn this stuff? Are they engineers? Did they learn these things by doing and reading the manuals? Is there a useful book out there? Clearly they use the handy wiki and FAQ located here on DIY Solar.

I've been relying on YouTube and blog posts and informational posts made by Victron and other companies (which are surprisingly helpful and well written!) but I am so far from understanding the nuances of this it makes my eyes cross.

What is the results of the energy audit you did? Understand that using solar/battery versus grid or generator that ratings are not what you actually get. You need to allow for all the losses. So as example your energy audit shows need of 500wh per day. Your system will likely need to be able to develop at least 3-4 times that in order to account for losses, loads and return to a state where you can start the next day without being already partially depleted. Thus 1500 to 2000wh. Does your design incorporate all of this? If not than every day you have to subtract from your battery the amount you do not meet full restore capacity from solar. This will give you run time until a generator or shore power becomes available.

My design totally does NOT incorporate all of this! This is fascinating and very informative.

We own a generator. My current plan is that if we *need* A/C or a heavy load item, then we are running the generator.

A 206ah 12v battery is able to deliver 10.3 amps for 20 hours before completely discharged (10.3 *12= 123.6 watts per hour for 20 hours). Or it can deliver ~2400 watts in 1 hour before dead.

ETA: There is also one other factor that I forgot to mention. Your panels might be sufficient to recharge your battery and supply loads during the peak of the day. However any additional power they could supply is lost once your batteries become charged. The panels no longer see the battery as loads. Amount of storage and amount of generation for loads is a strange dynamic.

That fact about storage vs. generation is really interesting and I am going to keep it in mind.

After a long discussion with my partner, we have decided that we need the RV solar system and battery bank to be able to keep the wifi router, laptops and phones, and basic RV equipment including the Dometic DM2672 refrigerator (it runs on propane but requires DC to keep the fan and other electronics going). We need to rein in the budget somewhat. So upgrading to the amazing builds that some others have kindly shared will have to wait for us.

Here's a screenshot of the energy audit. It's like all the things we regularly use, but some use could be cut back to conserve. I currently have one SOK 206Ah battery, and two 200W Rich Solar panels. I'm still trying to figure out the rest of my plan based on feedback from here. I think I will get a second battery. There have been many suggestions for ditching the stuff I already bought and getting an inverter/charger, but the cost on those is either high/good reviews, or low/bad reviews/warranty issues. So I am mulling over my options presently.

 

[SniperX]

I took a stab at editing an existing diagram I had and inserting your components.

View attachment 103491

This is like a masterpiece to my eyes... I am searching this topic too. VERY NICE.

 

[mccollums]

This comment is so incredibly helpful. Thank you for taking the time to write it. I knew there was some loss, but I didn't know these specifics. I recognize that the information is out there, but sequencing it all into something that makes sense to me is proving to be the difficult part. How do people learn this stuff? Are they engineers? Did they learn these things by doing and reading the manuals? Is there a useful book out there? Clearly they use the handy wiki and FAQ located here on DIY Solar.

I've been relying on YouTube and blog posts and informational posts made by Victron and other companies (which are surprisingly helpful and well written!) but I am so far from understanding the nuances of this it makes my eyes cross.

My design totally does NOT incorporate all of this! This is fascinating and very informative.

We own a generator. My current plan is that if we *need* A/C or a heavy load item, then we are running the generator.

That fact about storage vs. generation is really interesting and I am going to keep it in mind.

After a long discussion with my partner, we have decided that we need the RV solar system and battery bank to be able to keep the wifi router, laptops and phones, and basic RV equipment including the Dometic DM2672 refrigerator (it runs on propane but requires DC to keep the fan and other electronics going). We need to rein in the budget somewhat. So upgrading to the amazing builds that some others have kindly shared will have to wait for us.

Here's a screenshot of the energy audit. It's like all the things we regularly use, but some use could be cut back to conserve. I currently have one SOK 206Ah battery, and two 200W Rich Solar panels. I'm still trying to figure out the rest of my plan based on feedback from here. I think I will get a second battery. There have been many suggestions for ditching the stuff I already bought and getting an inverter/charger, but the cost on those is either high/good reviews, or low/bad reviews/warranty issues. So I am mulling over my options presently.

View attachment 103709

Do you have enough room for the SOK server rack battery (5.12kWh)? It's cheaper to buy one of those instead of 2 SOK 206Ah batteries.

Also, wouldn't be a bad idea to buy a Bluetti EB3A when they go on sale (Black Friday or a Prime day.. they are only 209$ on sale and will charge the phones and laptop if you have any issues with your main system. Throw in a portable solar panel with usb charging and you have something you can take on hikes that will charge phones and charge the EB3 in a pinch.

I am still learning like you, and thankful you have taken time to type all this out.. I was trying to motivate myself to do that today but didn't need to after your thread. My goal, if I feel comfortable enough with DIY, is to build a portable solar generator to run a small chest freezer and mini fridge in case of an extended grid outage. I'm struggling with the inverter decision like you...they get expensive QUICK. However, I'm not in a rush and I think I'm going to watch FB Marketplace for a deal on a used inverter.