Ready to jump in the solar world

[JimboC]

Looking to jump into the solar world. I want to boondock camp out of my truck. I am envisioning a 12/24 volt system, 400 watts of solar panels, 2 100 ah lithium batteries, more if needed, dc-dc charger from my truck battery, 2000- 3000 pure sine inverter, and battery monitor.
My power requirements.
1. Iceco refrigerator, 12 v 65 watts
2. LED lights
3. Water tank, 30 gallon with diaphram pump, sporadic use for showers and dishes.
4. Instant hot water heater 120 v, 10-12 kw. or is it possible to run a 240 volt heater on a 60 amp double pole breaker with the correct inverter.
5. Televison / Radios
6. Portable AC unit. 120 volts, 1200 watts. This is only to be used during the day by itself in a hot desert environment, full sun, panels directed at the sun. The only other electrical use would be the Iceco refrigerator. This will be very sporadic use in the hot desert. My wife can't take the heat for very long.
As you can see I am not an electrical engineer, the 400 watt package you have listed is a starting point for me. Whether it will be enough is what I am trying to find out.

 

[sunshine_eggo]

1. how many Wh/day?
2. how many Wh/day?
3. how many Wh/day?
4. This need requires a vast over-design. Instant hot water by electricity is a massive demand. Traditional W/H is much more practical.
5. how many Wh/day?
6. This is much like #4. A/C increases demand by an order of magnitude.

The 400W package would likely be fine for 1-3 and 5, but it won't even come close to handling 4 and 6. You need to be thinking 5-10X the capability of the 400W system and MANY thousands of dollars more.

To give you an idea, we have a 3kW PV system with a large custom 20kWh battery (About $5,000 in DIY LFP). This allows us to run our RV rooftop AC (about 1500W) for 8-10 hours per day in the AZ high desert and leaves only a little surplus.

I'm only using one of my two $2200W inverters. Even if I had them both running, they couldn't handle your instant hot water heater.

My $12K system couldn't handle your needs.

10-12kW is an absurd amount of power for an off-grid scenario. You want to boondock with a device that requires more power than any single device in my entire Phoenix house including my 5 ton A/C unit.

 

[timselectric]

You already have a great source for hot water.
The truck engine.
All that you need is a heat exchanger and a little bit of hose.

 

[740GLE]

Portable propane hot water waters are great options too, paired with propane you’re probably cooking with not too much more hassle.

 

[jvin248]

.

Instant hot water .... Not instant but since you are in Arizona you can likely use a solar shower setup, big black water bottle heats during the day.

I know a guy here in the North who bought a coil of black water sprinkler hose typically used for underground sprinkler systems, he tossed it on the ground next to his pool, and routed his pool's pump through it. He couldn't believe how hot the water was coming out of it. Coil that hose on the top of your camper and you'd have two hundred and fifty feet of hot water after 10am. Look up thermo-siphon and you might keep a barrel of water in the camper connected to that top coil that heats all day and releases heat inside the camper during the night, I saw a thermo-siphon used to heat a jacuzzi from a fire pit.

.

 

[JimboC]

Looks like I need to do some more homework. The water heater is now out of the equation. I will try to find out the watt hours needed per day and get back to you.
Thanks for your input.

 

[sunshine_eggo]

Looks like I need to do some more homework. The water heater is now out of the equation. I will try to find out the watt hours needed per day and get back to you.
Thanks for your input.

System Energy Audit and Sizing Spread Sheet

To get the spreadsheet, click on the orange button at the top of this page. This sheet is intended to help you plan your system. Fill it out down to the last decimal place, look at the results..... and then make your best guess;) Notes...

diysolarforum.com

 

[JimboC]

Looks like I need to do some more homework. The water heater is now out of the equation. I will try to find out the watt hours needed per day and get back to you.
Thanks for your input.

Thanks for the propane water heater idea. Much better than an electric water heater. That would take a large load off my project.

 

[littleharbor2]

If you must have air conditioning you might look at the new 12 volt A/C units offered by some of the reputable Mfg. They're not cheap and still require a reasonable amount of power. You would need a larger system than what you have proposed but might be a workable solution.

 

[JimboC]

Hello again: So I did a complete 180 degree turn on this. I bought a 22' travel trailer with a generator, Propane or electric refrigerator, roof top AC, propane heat. My new question is if I get the 400 watt solar package with alternator charging will that be enough to power the fridge as I drive. The AC is out of the question until I hook up the generator. Another issue is the space on the roof. Can I use 1 400 watt panel instead of 4 -100 watt panels. You input is greatly appreciated.
Jim

 

[j3rk]

If the refrigerator you mention really only pulls 65w of power at 12V, that's about 5.5A. So if you have a 200AH LFP battery, you could run it for ~36 hours before the battery is completely drained. 200/5.5. If you have 400W of power going into the battery, and are only pulling 65W out, you could easily run it as long the sun shines. A 400W panel or set of panels will most likely not actually provide the full rated power most of the time, but even at 75% you'd be putting about 300W into the battery while the sun is out.

While it's not in a mobile environment, I do have 400W of panels connected through an All-in-One inverter charger (MPP 1012) to a 200AH LFP battery, and it easily fully recharges my system each day after I pull about 50-150W out of it with my desktop computer for 3-5 hours a night after the sun sets, which is similar to your 65W refrigerator draw. During the day, the panels generate more power than is needed, so it puts the rest towards recharging the battery. If the fridge ends up being your only real draw, you may not even use the alternator power most of the time with a big enough battery.

As for your question about 1 vs 4 panels, it doesn't really matter. Larger panels like that aren't really designed for mobile environments though, so the constant vibration and flexing of driving down the road may cause issues in one big panel. Four smaller panels will have more weight to them, but because they are smaller and there is much less glass spanning between the frames, the vibration is less likely to affect them. I drove around with two 100W Renogy panels on the top of my truck for 3 years before they were retired to the back yard charging setup earlier this year. Neither appears to have any damage from that experience, and they generate a good amount of power still.

Here is a screenshot from the WatchPower app that shows how much I am generating right now (about 11am, full sun) vs. how much I am pulling to run the desktop computer and monitor while typing this post. I have my home office set up to be off-grid, so this is similar to your plans.



And here are the Renogy 100w panels providing this capacity. Four of the panels are wired in series to provide the power in the above screenshot, and the 5th is not connected, just there for other experiments.

 

[JimboC]

If the refrigerator you mention really only pulls 65w of power at 12V, that's about 5.5A. So if you have a 200AH LFP battery, you could run it for ~36 hours before the battery is completely drained. 200/5.5. If you have 400W of power going into the battery, and are only pulling 65W out, you could easily run it as long the sun shines. A 400W panel or set of panels will most likely not actually provide the full rated power most of the time, but even at 75% you'd be putting about 300W into the battery while the sun is out.

While it's not in a mobile environment, I do have 400W of panels connected through an All-in-One inverter charger (MPP 1012) to a 200AH LFP battery, and it easily fully recharges my system each day after I pull about 50-150W out of it with my desktop computer for 3-5 hours a night after the sun sets, which is similar to your 65W refrigerator draw. During the day, the panels generate more power than is needed, so it puts the rest towards recharging the battery. If the fridge ends up being your only real draw, you may not even use the alternator power most of the time with a big enough battery.

As for your question about 1 vs 4 panels, it doesn't really matter. Larger panels like that aren't really designed for mobile environments though, so the constant vibration and flexing of driving down the road may cause issues in one big panel. Four smaller panels will have more weight to them, but because they are smaller and there is much less glass spanning between the frames, the vibration is less likely to affect them. I drove around with two 100W Renogy panels on the top of my truck for 3 years before they were retired to the back yard charging setup earlier this year. Neither appears to have any damage from that experience, and they generate a good amount of power still.

Here is a screenshot from the WatchPower app that shows how much I am generating right now (about 11am, full sun) vs. how much I am pulling to run the desktop computer and monitor while typing this post. I have my home office set up to be off-grid, so this is similar to your plans.

View attachment 118111

And here are the Renogy 100w panels providing this capacity. Four of the panels are wired in series to provide the power in the above screenshot, and the 5th is not connected, just there for other experiments.
View attachment 118113

You mentioned using one of the all in inverter units, when I read the reviews there is always a few really negative reviews on the reliability of these units. While I think these are perfect for what I want to do, this issue makes it hard to go that way. My plan is to travel in 3 week increments 3-4 times per year. I am not looking for full time RV living. Will gives it great reviews but you never get a long term review and its reliability. WWWD, what would Will do. What would you do.
Thanks Again

 

[littleharbor2]

Reviews need to be taken with a grain of salt, so to speak. I only give them any value when I can tell that the reviewer knows what he is talking about. Most one star reviews are written up by people who don't have a clue what they bought, expected it to do a job it wasn't designed for, and don't know what they're doing.

 

[j3rk]

You mentioned using one of the all in inverter units, when I read the reviews there is always a few really negative reviews on the reliability of these units. While I think these are perfect for what I want to do, this issue makes it hard to go that way. My plan is to travel in 3 week increments 3-4 times per year. I am not looking for full time RV living. Will gives it great reviews but you never get a long term review and its reliability. WWWD, what would Will do. What would you do.
Thanks Again

As @littleharbor2 mentioned, you have to take reviews with a grain of salt. I understood what I was buying going into it, and I've been very happy with the results of my little experiment over the past 8 months. It has given me enough confidence at a low enough price point to now consider upgrading to a 6500-type device on a 48V server rack battery and moving more than just my home office off-grid. I'm just waiting for my wallet to gain the same confidence. ?

 

[JimboC]

As @littleharbor2 mentioned, you have to take reviews with a grain of salt. I understood what I was buying going into it, and I've been very happy with the results of my little experiment over the past 8 months. It has given me enough confidence at a low enough price point to now consider upgrading to a 6500-type device on a 48V server rack battery and moving more than just my home office off-grid. I'm just waiting for my wallet to gain the same confidence. ?

Getting close to pulling the trigger on a system. Would like some input into my plan.
3 - 190 / 200 watt panels in parallel
Ampere Time 200AH lithium, no heater. With charger. Will not be camping in the cold, batteries will be in a heated area if it gets real cold.
40 amp BN 40 amp MPPT charge controller with remote monitor.
2000 - 3000 watt inverter, I will not be running the AC on solar power.
DC to DC charger.
My plan is to mount the equipment under the bed storage which is at the front of the camper. By removing the lead acid battery from the tongue and placing the solar equipment back a few feet I lessen the tongue weight a little. I have a Grand Design 22MLE. Trying to save space in the only pass through storage compartment.
My thought is to run a heavy cable from the inverter to the shore power plug on the back of the camper. 2 reasons for this plan. I can run the propane / electric fridge while I am driving under electric power. I can then simply unplug the this cable if I go to an RV Park and hook up to a 30 amp service. I also have a 3600 watt generator with a 30 amp service that I can connect if needed. I will need to unplug the converter, disconnect the 7 pin plug power to the original lead acid battery. I will need the truck to power the electric trailer brakes and tail lights. This seems like an easy hook up that is pretty safe. No exotic wiring needed, the solar side of the package acts just like a shore power hook up. Nothing gets cross wired.
Your thought are always appreciated.

 

[JimboC]

Getting close to pulling the trigger on a system. Would like some input into my plan.
3 - 190 / 200 watt panels in parallel
Ampere Time 200AH lithium, no heater. With charger. Will not be camping in the cold, batteries will be in a heated area if it gets real cold.
40 amp BN 40 amp MPPT charge controller with remote monitor.
2000 - 3000 watt inverter, I will not be running the AC on solar power.
DC to DC charger.
My plan is to mount the equipment under the bed storage which is at the front of the camper. By removing the lead acid battery from the tongue and placing the solar equipment back a few feet I lessen the tongue weight a little. I have a Grand Design 22MLE. Trying to save space in the only pass through storage compartment.
My thought is to run a heavy cable from the inverter to the shore power plug on the back of the camper. 2 reasons for this plan. I can run the propane / electric fridge while I am driving under electric power. I can then simply unplug the this cable if I go to an RV Park and hook up to a 30 amp service. I also have a 3600 watt generator with a 30 amp service that I can connect if needed. I will need to unplug the converter, disconnect the 7 pin plug power to the original lead acid battery. I will need the truck to power the electric trailer brakes and tail lights. This seems like an easy hook up that is pretty safe. No exotic wiring needed, the solar side of the package acts just like a shore power hook up. Nothing gets cross wired.
Your thought are always appreciated.

Update- 60 amp charge controller is required

 

[littleharbor2]

Update- 60 amp charge controller is required

Funny, how that works. You could double the PV @ 24 volts and quadruple the PV @ 48 volts with that same 40 amp controller, and not even have to upgrade the PV input wire.

 

[JimboC]

Funny, how that works. You could double the PV @ 24 volts and quadruple the PV @ 48 volts with that same 40 amp controller, and not even have to upgrade the PV input wire.

Anyone have any thoughts on this plan.

 

[sunshine_eggo]

Anyone have any thoughts on this plan.

I don't see a plan. I see a statement.

The statement is true. A 40A controller on a 24V system can provide 2X the charging as on a 12V system and 4X on a 48V system.

 

[timselectric]

It seems like a good start for planning a plan.