Left With Solar Set-Up Not Completed, Help Me Understand What I Have and What I Need to Do

[RVs2solar]

Hi Everyone-warning this is a lot to digest LOL
I am new to this forum and have read many posts-I am impressed with the amount of knowledge out there and the people using it to help others. On that note, here is our story:
Moved from city and now live in the high desert-4 corners area. We bought 2 RV's to live in for a year while we build our cabin, they were used but well maintained and 40 acres of land on the side of a volcano/mountain. We installed our septic (we are GC's) (it is permitted) and then hired a local to design and install a small system for the 2 RV's to run off of. We like to keep our dollars local and also we like to support our vets. Well, needless to say no good deed go unpunished. We bought what he asked us to-ran around the state picking up merchandise etc. This is what we have purchased:
-4, 350w solar panels
-we built custom racks with fasteners from the local solar company.
-a Sungold 4000w, 24v inverter
-we paid another local to make cables, they are highly rated
-Victon controller
-8, 29dc Walmart marine batteries

Other sundry items the tech said he needed. We have 2 generators, CAT 7500, Generac 8000 for back up.
The tech was supposed to make a proper electric connection from the large RV and we have the electric hd cord running from the large RV to the small one.
Ugh, well he did half of it. We have the cord running from the large RV to the small RV to provide AC, that is all we have. We cannot use the electric in the small RV because he started working on the inverter in the small RV, tore it open and left it. The system we have will not allow us to use the large RV AC so we have a small one in there another in the small rV. The large RV seems to run fine on the sun and sometimes the small one too, once we get a cloud though its over. The batteries seem to hold a charge for about 45 minutes with the AC's on and it will keep above 24.6v at night when nothing is on but phone chargers and fans. We were told to use the generators until the batteries go to float (29v) then turn them off, if the batteries go below 24.7 then turn the generator back on.
I cannot even begin how crazy this system is-we are constantly having to pull up the app on the phone to check the power, turn on and off generators, AC's not working, the list goes on and on. Its nuts. Basically we are left not knowing what this guy did, he hasn't returned, we paid him for not only the solar but for the generators to work properly (not happening), install proper plugs, install a alarm to tell us when the system is running low, install a switch to auto turn on the generator, etc.
I know we need to find another tech, but before we do I'd like some opinions on what to save, what to junk, and what is a realistic overhaul on the system.
Ideas are appreciated! Thank you for any suggestions!
We literally run only 2 AC's and charge our phones and laptops, no TV, etc.

 

[Samsonite801]

Those AC units on RVs are power hogs... I have 2 Dometic 13k BTU roof AC units on my motorhome, and with a 12v 2800w Magnum inverter I can only run one at a time (AC units even have soft starters in them).

My system has 22 KWh of battery, two Victron 250|100 charge controllers, and 8x 405w solar panels and here's the problem I have. I have plenty of battery and inverter to run one AC unit which is ok for now, have to alternate later on to run the back one more to cool down the bedroom before bedtime.

The issue I have is even with 8x solar panels it works great at full Sun, will keep the battery at 100% all day until about 4pm or 5pm when the Sun gets too far side angle toward West, then it starts dipping into battery. Clouds rolling over does the same thing, starts dipping into battery with AC on.

This isn't bad for the battery as I have plenty of KWh, the problem comes the next day. If I draw the battery down to even like 59%, then the next day it will never charge up if I am running the AC at same time. So I have to turn off the AC and wait til battery gets back to 100%, but is 12:00-1:00pm by that time, so it is very hot again while waiting.

Literally, without AC I have 5-10 days of battery life, and with AC I have 7-8 hours of battery life.

So for now I am building another set of solar arrays, to add in 8x more solar panels (total of 16x 405w panels, 8x per bank), to be able to charge the batteries faster and run AC at same time. I am also looking into switching out the AC units for inverter type roof units, or mini-split type units as they are much lower power consumption.

So unless you want to run on generator power a lot, you may want to size your solar system a lot bigger, and also look into just switching to a 48v All-In-One inverter setup, and have maybe 32 solar panels, and get gobs of battery. Or look into mini-split / inverter type AC conversion.

An energy audit would be helpful for you, to calculate exactly what your needs are and what you want out of solar, and what you want out of generator.

And you don't really need a new tech guy, just hang out here a lot and learn how to build it yourself, you can do it!

 

[12VoltInstalls]

we are left not knowing what this guy did, he hasn't returned, we paid him for not only the solar but for the generators to work properly (not happening), install proper plugs, install a alarm to tell us when the system is running low, install a switch to auto turn on the generator, etc.

Excellent job describing the basics of your equipment.

Observations: I didn’t do any math but from a somewhat educated totally wildhat guess perspective you have roughly 1/4 of the battery storage capacity you need at a minimum based on assuming 1400W of solar is sufficient for your purposes. I like lead acid batteries for a lot of reasons but that doesn’t mean they’re always the best choice.
In your case that’s only 200Ah of usable storage at 24V nominal. Unless you like spending lots of money repeatedly you don’t use them as 800Ah/12V 400Ah/24V capacity.

Victron has some SCCs that can integrate auto-start of generators. I’m not familiar with their products but I know people do that. Epever (a quality mid-shelf product line) can do that as well. Maybe if you post the model and specs of the victron SCC folks that know can comment.

You can use what you have but I’d be inclined to acquire an MPPSolar AIO and add some panels. That will simplify some things if adding gen-support from victron is costly. But victron multiplus is also an option that will integrate well with an RV’s systems.

It sucks you were ripped off but it sounds like the right electrician could get what you have functional since it is working to some extent now.

 

[Mattb4]

Sorry you ended up with a system that does not meet your demands. All too often that is the case with the alternative energy field. The problem is one of education and most people just wanting to sell you something do not want to take the time or effort to explain all the details.

The difference between on grid and off is really quite staggering for most folks to envision. Take for instance the average US home with its 200amp 240vAC supply from the utility company. What this means is you have available 24/7 (other than times of loss or utility overload such as the recent heatwave is causing) 48,000 watts of power to draw (Watts=V*A). To try to build a off grid power supply that equals that you need a generator that is minimum rated at 48kw continuous duty. However most households have considerably less load needs than running full power all the time.

If you look at your electrical bill (can be found online even if you no longer get one mailed to you) it will give you the monthly kwh amount that you used. Some even will give a daily average. Keep in mind that is average and some days can be less or more. 1 kwh is 1000 watt hours. A watt hour is simply a load that draws a continuous watt for 1 hours time. Take a led light bulb rated at 9 watts (60 watt equivalent). If you have it on for 5.5 hours it will have drawn 49.5wh. Every thing you run has a watt requirement and as they start and run will add up to your loading total for the day.

So you add up all your loading needs and now want to supply it with something other that the grid. If you buy a standby generator you must needs to have sufficient ratings to supply that power for the day as well as supply starting surge power for anything you wish to run. So often that means a fairly large generator if you do not monitor what loads are being used. Large generators consume more fuel and cost more. By watching the loads you start and run at one time you can get by with a smaller generator.

About batteries. They are a fixed amount of power stored. Once you use that power they need to be recharged. By the nature of a fixed source you can not think of them like a generator or your utility power. Understanding batteries is hard for most people. Take the time to learn all you can.

Now we get to solar power. Solar power is from the sun. Obvious you say. So what does this mean? It means you need to have the sun shining and it also means that the power you get varies from the time of sunup to sundown. Unlike a generator that can develop rated power continuously. But the power they generate, if it is more than is being used by you, can be sent to storage, either a battery or to the grid as a reciprocal agreement to offset grid supply.

So armed with knowledge you must than make up your load needs and and figure a way to supply them. A whole lot more things will now have to be taken into consideration (such as the crappy Chinese components on the market) in order to build your system. But with basic knowledge you can at least know where you are heading to.

To sum up:
Grid power: Near infinite at a home level
Generator: Limited by size and fuel requirements.
Battery: Fixed amount
Solar: Sun dependent and limited by size of total array plus the need to store power.

 

[Samsonite801]

Excellent job describing the basics of your equipment.

Observations: I didn’t do any math but from a somewhat educated totally wildhat guess perspective you have roughly 1/4 of the battery storage capacity you need at a minimum based on assuming 1400W of solar is sufficient for your purposes.

In my humble farm mechanic background, I would take whatever I thought I needed on solar requirement and easily double it. Even at 2800w, that is only 2800w at best case, when the clouds roll in it may drop to 500w and kill all aspirations you had about it ever collecting 2800w. I'd rather try to size the solar side for a worse case scenario to give extra buffer.

Even on my 8x 405w panels, the best I've seen out of it is around 2700w in full Sun (at good angle and clear skies), but is more often than not, less than that in real life. So far my experience is that the 405w STC spec they publish for my panel is a dream... Especially when they get a little dust coating on them when it's time to clean them.

 

[Hedges]

You need way more than 4x 350w solar panels.
Panels are fairly inexpensive, especially used. Shipping cost dominates unless you buy by the pallet full.
You'll need enough charge controller to make use of them.

Best if you can understand how and do the work of mounting panels, wiring them in one or more series/parallel arrays to get voltage and current within limits of charge controller, connect batteries and inverter.
A basic PV system isn't very complicated, but need correct wire gauge for amperage and open circuit voltage of PV panels must never exceed spec of charge controller. Assume Voc of panel increases 16% for a first estimate.

Initially, you can use generator manually by unplugging a load from PV system and plugging into generator when needed. If a charger is available (possibly as part of inverter) the battery can be recharged at same time. Automatic generator starting and switching of AC between sources can come later, if ever. Using a generator should be infrequent with enough PV.