Stupid Simple Solar System Advice

[Strangebird00]

New here to the forum but I figured this could be a good place to hopefully get some advice on hooking up the most basic of basic solar setups. I am hoping someone can look at my plans and let me know if I am looking at this the right way. My wife and I have a 16' Clipper Camper and every once in a while we go to a campground that has absolutely no electricity. I am completely illiterate when it comes to electricity in general but I have been watching tons of videos trying to wrap my brain around how to set up a simple system with my camper. We are slowly trying to buy the pieces we need to make everything work as I am learning the process.

So far I have a 100W "briefcase" panel from Harbor Freight (link below for reference) that I have had decent luck with using alongside my Jackery power station.
https://www.harborfreight.com/home/electrical/solar/100-watt-solar-panel-briefcase-57991.html. How long do you think it would take to charge 2 batteries with a 100W panel in good sunny conditions?

I have also upgraded the battery box to a double battery box with the expectation of adding a second Marine Deep Cycle Lead Acid Battery (I think that would give me 100Wh between the two batteries (50Wh each as I was told you shouldn't run them much lower than 50%)).

I am not sure how fast I could charge up these batteries with a 100W panel, but worst case, I can run a generator at the campground for 2 hours. I recently got a 2500W Peak/1850W running generator I can use if need be.

I found out that my outlets in the camper only work if the camper has power meaning they do not run off the batteries so I believe I will have to have an inverter. After learning that, I am thinking of installing a 1000-2000W Pure Sine Wave inverter. Would I also need a shutoff switch between the battery and the inverter?

I have been trying to find a good video of installing a simple system like I have in my head, but every video I have found is people wanting to run their entire camper off the inverter. We will only been needing to run a small fan, the LED lights, phone chargers, and the water pump. So I think the plan is to just plug stuff directly into the inverter if it requires a plug. One other Idea I had (if its possible) is to install a wall socket in the camper and wire it to the inverter so that I can hide the inverter under the bed and be able to use the wall outlet for anything I need to run off the batteries/inverter.

Is there some LED screen or something I could install to see the volts and wattage I am drawing from the batteries as well as what I am getting from the solar/generator or would this information be provided with the solar controller?

Here is the simple system I drew out to help it make sense in my mind. The thing I do not know about it fuses and all that. I have seen people say you need a fuse between the battery and the inverter but I do not know. I don't know what size you would need either.


If you have made it this far, Thanks for taking the time to read it. Please let me know if you guys think I am on the right track here. Also, if there are any components you can recommend, that would be fantastic. Keep in mind, I am trying to do this as simple and as cheap as humanly possible as this will only be used in the handful of times a year we go to this one particular campground.

Thanks again ahead of time for anyone that takes the time to read this and respond!

 

[jackiemac]

You'll get lots of help on this subject! Good luck with it.

 

[Mark_K5LXP]

Your concepts are valid, just lack context in terms of real world operating parameters.


I have a 100W "briefcase" panel from Harbor Freight
...
How long do you think it would take to charge 2 batteries with a 100W panel in good sunny conditions?

You say you have two marine batteries, nominally 100Ah each.

Solar isn't like shore power, just because you have a given wattage panel doesn't mean you get that power whenever the sun hits it. The only time it will even come close to that is "solar noon" in the middle of summer. Different times of the day, the month of the year and where you live (latitude) will all (negatively) affect output. Throw in some clouds, dust or pollution/smoke and it gets even lower. Just pointing out that there's a lot of margin to solar panel output and at best all you get is an estimate of the power. But you have to start somewhere using "nominal" conditions. Half the rated power times 6 hours is one that I use, so a 100W panel * .5 * 6 is 300Wh.

Your two marine batteries you say are 100Ah, so total 200Ah. There's subtleties to charging batteries which makes this number somewhat fluid but we'll keep it first order calculations for now. 300Wh per day is 25Ah, so from "dead" it would take your 100W panel 8 sunny days to recharge these.


50Wh each as I was told you shouldn't run them much lower than 50%

This doesn't apply to what you're doing. Your 200Ah batteries are 200Ah for your purposes.


I can run a generator at the campground for 2 hours.

That won't get you 100%. Depends of course just how discharged they are, and the size of your converter but even a 55A one would only restore about half the total charge in 2 hours. In order to get 100% there's a period where the batteries won't be receiving 100% of the converter output, and will take literally hours to complete. That's one situation where solar is nice, they can just sit there and "soak" the needed Ah to restore the charge. If 2 hours is your only generator window then you have to budget the aggregate of your generator, solar, storage capacity and anticipated usage. You can get that to work, but requires a more specific system configuration.


I am thinking of installing a 1000-2000W Pure Sine Wave inverter. Would I also need a shutoff switch between the battery and the inverter?

The inverter you pick may not need a mechanical cutoff. But the elephant in the room here is the size of the inverter. Do you know you need this amount of power or is it just a WAG? Because this amount of power can't be supplied with a pair of marine batteries, at least not for long.


We will only been needing to run a small fan, the LED lights, phone chargers, and the water pump.

For those devices specifically, you don't need an inverter at all. Those functions can all be done directly from 12VDC.


Is there some LED screen or something I could install to see the volts and wattage I am drawing from the batteries

It's called a battery monitor and you can get very simple, to very complex ones depending on what data you want to observe and how. You can get as simple or as fancy as you can afford.


The thing I do not know about it fuses and all that.

Once you know your desired system configuration, circuit protection and control can be determined from there. So that's your homework assignment - figure out what you want it to do when it's done, and work backwards from there to determine the functional units that will meet that requirement. Based on your initial post I don't think it's as big or complex as you're envisioning now. Measure or estimate the power you will be drawing and for how long, and from there the equipment and configuration can be mapped out.

Mark B.
Albuquerque, NM

 

[Ohiosnowbird]

Our farm is off grid so we’ve learned some things about solar. Electric fences, remote controlled gates are some of the applications we’ve tinkered with. With our RV, it came with the solar system we would have installed. It charges the batteries while cruising down the highway.

Our RV system uses lithium batteries. At the farm we learned some lessons with lead acid, so it’s lithium batteries all the way. Here are some links to articles dealing specifically with RV solar systems:

RV Solar Panels: A Guide For Beginners

What are RV solar panels? How do they work, what can they do for you, and are they worth the investment? Lets take a closer look.

battlebornbatteries.com

The Truth About Lead-Acid Vs. Lithium-Ion Batteries In RVs

Is there much of a difference between lead-acid vs. lithium-ion batteries? Learn the pros and cons of these two main RV battery types.

battlebornbatteries.com

The Unfortunate Truth About RV Solar Power

There are both advantages & disadvantages to setting up an RV solar power system. These are some of the downsides that you'll want to consider.

camperreport.com

Good luck with your project!

 

[Mark_K5LXP]

I'm throwing the BS flag on the Lead acid vs Lithium "truth". There is no question lithium performance beats lead in most respects but they paint an unrealistically bad picture of lead. Their examples are decidedly skewed in their favor and conveniently glosses over some realities of deploying a lithium system. Funny thing, coming from a purveyor of lithium batteries. Their solution guarantees a high initial investment which one may never realize a decided advantage of, so it wouldn't be a reference I would base any system decision on unless money is not a factor.

Mark B.
Albuquerque, NM

 

[Ohiosnowbird]

I'm throwing the BS flag on the Lead acid vs Lithium "truth". There is no question lithium performance beats lead in most respects but they paint an unrealistically bad picture of lead. Their examples are decidedly skewed in their favor and conveniently glosses over some realities of deploying a lithium system. Funny thing, coming from a purveyor of lithium batteries. Their solution guarantees a high initial investment which one may never realize a decided advantage of, so it wouldn't be a reference I would base any system decision on unless money is not a factor.

Mark B.
Albuquerque, NM

I agree with you, but it had most of the bad stuff we’ve encountered on the farm. We have remote controlled gates so we don’t have to leave a vehicle to open a gate, lithium there, it’s where we’ve seen the best advantage. With solar electric fences, we use lead. It’s not systems you’d have with some of the applications on an RV but our farm applications have tested the lithium vs lead theory for us. What we have found is that though lithium initial costs are almost triple, the number of charge cycles you get eventually covers the cost. When I wrote our RV came with a solar system we’d install, I didn’t mention, because I wasn’t aware then, it is lead based. We are going to eventually upgrade to lithium based on our experiences at the farm.

The other part of the lead vs lithium is the weight issue in the RV.

 

[WME]

What do you need to run off 120v outlets.?
My second solar setup was 225AH LA batteries and 300w of solar. After a week of off grid, with no efforts to conserve and sorta good solar, my batteries would be around 90%

 

[Strangebird00]

First off, Thanks for all the reply's! So let me start off and say I understand lithium is the way to go but as little as I will be needing to utilize this setup, I can't currently justify the cost of the batteries. Most of the time we go camping, there is power hookups. Its only a couple times a year that I would need this and it would be no more than 3-4 days before I would be back to some sort of power hookup.

So I went out today and doublechecked everything in the camper. The only outlet that will run without power being hooked up is the USB outlets. None of the plug outlets will work, which is why I initially said I think I would want to have an inverter in case I came across something that I needed to run. The inverter is more of a "O crap, I need somewhere to charge this" kind of situation and I understand that I really cant do anything large with it like a fridge or oven or something. Well, I guess you could but it would deplete the batteries rather quickly.

Here is what I KNOW that I want to run via the batteries. If I am utilizing these devices, I can't imagine it will be that big of a draw. In most average circumstances, would a two 100Ah battery bank suffice for this?


As for the solar portion, again I currently only have a 100W panel in my possession and I can always upgrade that. If each day, I am only depleting a small portion of the battery bank, I would imagine that between the solar or my generator, it should would out ok right?

As for the inverter, the size is all a guess. I just figured if I had a 1000W Pure Sine Wave inverter, it would give me an option if I ran into a situation where I had to run something small (with the understanding that it would deplete faster of course depending on the draw).

For the Battery Monitor, I just want to be able to see what power I am inputting back into the system from the solar/generator while also showing its current percentage and what's being used live.

Maybe this post kind of simplifies what I am looking to do. I think most things will run fine though 12v. I am just curious if this is a small enough draw that I can get through 3-4 nights with trying to top off the batteries with solar/generator.

 

[WME]

The 12v stuff you listed will run a LONG time off of 200ah batteries and 100w of solar.
The fly in the ointment is the inverter. A 5 amp 120v AC, something will draw 50 amps+ from your battery. Your 200ah of batteries would last 2 hr safely. But your 100w panel would take 3-4 days of good sun and no power use to pump things back up.
400w of solar would get it done in about 1 day. 400w of solar is about $350, a 30 amp semi decent mppt controller is $125-$150

 

[Ex-Calif]

Looking at your power consumption I agree that 2 AGMS will provide plenty of power.

Like others my concern is the 2000W inverter - that is a ton of power draw, if used, off the batteries.

I have a 400W inverter that I run the TV and WiFi off of when I am off grid.

If you attempt to run anything with heating elements (coffee makers, waffle irons, kettles etc.) or the microwave or heaven forbid A/C I think you will be really disappointed.

On the boat we used to run the generator in the mornings to make breakfast, make drinking water and heat up the water tank. We'd also run it in the evenings for the same purpose as well as running the A/C for an hour or so to cool the cabin for the evening.

 

[Mark_K5LXP]

For an O Crap scenario I don't see myself doing a whole-house inverter installation. A portable/temporary setup you just haul around is more than adequate to fill in any gaps. I carry one around in my pickup and it's the same one I used to run my popup camper back when I had it. I recall it's 400W, square wave, I think I got for $10 at a fleamarket. Perfectly good for charging power tools, laptops, running some 120V lights. If you're particular and believe you want or need modified or pure sine then just get one of those. For DC input I use some anderson power pole connectors on the inverter, and at the house batteries. From there I can run a standard 120V extension cord to wherever. Add a basic outlet strip to provide some breathing room for cords and wall warts and check the box. The whole mess fits in a shoebox size storage box along with other electrical bric-a-brac I keep in my tools and spares compartment. Most often I use this inverter to run some 120V party lights we string up on the awning sometimes, and to charge cordless tools. Just to plant the idea in your mind, I'd run the inverter off my truck battery and charge the house battery in my trailer with it. Since you have a generator that's probably superfluous but it exemplifies the utility of a portable inverter you can plug into whatever, and use wherever.

Per above, all your other loads are easily handled by the storage you have, and should already be powered by the OEM wiring. You want to get some kind of battery monitor no matter what. You need to have some idea how much gas is in the tank so to speak, takes some of the wonder out of whether you can run stuff or not, when to run the genset, or if you're set for the moment. At face value it looks like even your 100W panel would be enough keep up with your setup there. At a minimum it would reduce the deficit and it wouldn't surprise me if you could go a couple weeks without a generator.

Mark B.
Albuquerque, NM

 

[Ex-Calif]

You want to get some kind of battery monitor no matter what. You need to have some idea how much gas is in the tank so to speak, takes some of the wonder out of whether you can run stuff or not, when to run the genset, or if you're set for the moment.

In terms of monitoring I am a bit of a snob. Poor monitoring is almost as bad as no monitoring - But on a simple system I could never justify a high end monitoring system.

I have gotten by for 4 years using only the voltage read out on the 400W inverter. If voltage drops below 12V I start troubleshooting as steady state is almost always 13V+ unless my loads are high for some reason. At 11.5 I am starting to panic - LOL...

 

[Mark_K5LXP]

Last year I upgraded mine from a cheapie to a hall sensor unit (just cheap) that counts Ah but I don't like how it self resets, and I end up just watching volts and amps manually like with the cheapie anyway. Since all I care about is how close to empty I am I'm resisting the urge to buy a "real" monitor because I don't really care about the area from 20% to 100%. Volts and amps tells me enough, just like your inverter meter. I correlated the OEM 4-LED batt level gauge to voltage and it's pretty much worthless since you need to know current to get any useful information from that, so the takeaway is even with my battery knowledge, there's no way that gauge can be used with any degree of confidence. "E" could be anywhere from 30% to dead. But the $20 monitors can get you there from here with some basic observation. Or just get the victron and be done with it.

Mark B.
Albuquerque, NM

 

[Strangebird00]

I think I understand how I need to handle the solar now since it sounds like everything is going to work since I am drawing only very small loads from the battery.

As for the inverter. One thing I wanted to run by you guys. Say I installed a 1000W Inverter into the camper. It's only going to utilize the batteries if something is plugged in correct? For instance, If i plug in a small dehumidifier that draws maybe 50Watts, It's only going to pull 50 Watts off my battery correct? I guess what I am getting at is having a 1000W inverter is not necessarily a bad thing right? It is probably overkill for what I need, but If I am using small stuff on it like the dehumidifier at 50Watts, it would be fine?

 

[WME]

I think I understand how I need to handle the solar now since it sounds like everything is going to work since I am drawing only very small loads from the battery.

As for the inverter. One thing I wanted to run by you guys. Say I installed a 1000W Inverter into the camper. It's only going to utilize the batteries if something is plugged in correct? For instance, If i plug in a small dehumidifier that draws maybe 50Watts, It's only going to pull 50 Watts off my battery correct?

NOPE, an inverter that is on but has no load has an idle current and over a 24 hr day that can be a lot.
Most inverters have an on/off switch that shuts things completely off
Nope again. A general rule of a 12v DC to 120v AC inverter is there is a 10:1 ratio.. So 50w is about .5 amps from the inverter, that equals about 5 amps from your battery

 

[Strangebird00]

NOPE, an inverter that is on but has no load has an idle current and over a 24 hr day that can be a lot.
Most inverters have an on/off switch that shuts things completely off
Nope again. A general rule of a 12v DC to 120v AC inverter is there is a 10:1 ratio.. So 50w is about .5 amps from the inverter, that equals about 5 amps from your battery

is that 10:1 ratio the same between a Pure Sine Wave and a Modified?

 

[John From Detroit]

As for the inverter. One thing I wanted to run by you guys. Say I installed a 1000W Inverter into the camper. It's only going to utilize the batteries if something is plugged in correct? For instance, If i plug in a small dehumidifier that draws maybe 50Watts,

Closer to 60 watts from the batteries. But basically you have the right idea.

 

[Mark_K5LXP]

Just to have an inverter "on" draws power, and generally the larger the inverter the greater this idle power. Even the "smart" inverter I had that would sense a load before turning on drew a bit of current for the monitoring, like 250mA. But then when it woke up it didn't matter if it was even a small load, the idle current "overhead" is the same. If you were powering a large load the impact of this idle current is lower because it's a smaller percentage of the overall power drawn vs delivered. But at light loads, it's a greater percentage of delivered power so overall efficiency is lower. Ideally you size the inverter to the load to keep efficiency up. For the example "50W dehumidifier" you wouldn't need a 1kW inverter, a 100W one would be more than enough. I get that you want to cover all the bases because you don't know what you want to power but just be aware of the idle power of larger inverters. At a minimum you'd keep the thing unplugged or turned off so at least you're not burning power just waiting for you to plug something in once in a while.

Mark B.
Albuquerque, NM

 

[WME]

A pure sine inverter is about 10% more efficient in converting DC to AC. AND the equipment runs more efficiently on pure sine.
Depending on what you're actually running there may be a 25% total difference.

 

[Strangebird00]

I think I am going to focus on making the solar part of it work initially and worry with the inverter a little bit down the road.

For the Solar Controller, If I plan to run 100W solar panel currently and possibly upgrade two 200-300W down the road, what controller would you go with? Would a 30Amp controller suffice?
Just a random one I was looking at on Amazon, Beleeb Bluetooth Solar Controller. If you have any recommendations on others, I am all ears as well.

Also, I've seen a few videos that recommends this for connecting to the controller. Have any of you utilized these?
Fused SAE/Battery Cable

Last thing, I am trying to decide if I should install a small SAE port on the side of the camper or just leave a lead coming from the battery to connect it there. What have you guys used for connecting? I feel like putting in a SAE port would look nice aesthetically but I don't know.

Thanks again for all the information. You guys are greatly helping me out and it means a lot. Hope you are sick of all the questions yet LOL.