Already outgrowing my new solar system

[Greendream]

Or perhaps I didnt size it correctly. We are off grid and have 20pc 195w panels with 345AH of LFP batteries. Now that its summer and the rainy season is here, we cant keep up with AC use in the campers on hot days where it can be cloudy. I am thinking the solution is to get another 5 panels in series should at least start pushing some decent amps to the batteries even with our inverter load.

I thought about getting larger, more economical panels but that would require another SCC and wires.

We cant really drop our inverter load since we have pets in the RV on 95F days while we are building the house.

My question is, for $1.2k i can get 5pc 195w panels like I have and mounting hardware. Alternatively, for about $100/ea I can get 280w panels. I already have a NIB midnight classic 250. I would just need wire to run from the panels to the classic 250. Id rather sell the classic 250 to recoup some cash. Would I be better off in the long run with 2 SCC for the different brand panels or should stick with the brand I have and just keep building on it? My PT100 SCC has room for more amps. I haven't seen over 40 amps with my current setup.

The batteries suggested charge current us 50A with max charge current 100A.

Trying to make the best decision.

Redundancy is very appealing..

 

[pollenface]

That's a seriously small battery for 3.9kw of panels.

What is an estimated figure of your daily energy requirements?

 

[Greendream]

That's a seriously small battery for 3.9kw of panels.

What is an estimated figure of your daily energy requirements?

Sorry I forgot to mention it's 345AH @ 48V. I based the system from our finished off grid home, where we wont be using any AC. We did a rough calculation prior to ordering and figured we need 10-12000 watts/day.

 

[chrisski]

For sticking to panels, in my signature block there's a way to calculate mismatched panels if you want to go to the same SCC. I only have an RV build, but one of the reasons I went to multiple charge controllers was to have some redundancy if one ever gave out. Because of that, I'd go with the second SCC. That way I could limp buy for a few days until a replacement showed up.

Is your rough calculation correct of 10 - 12 kwh? Seems like 16kwh battery bank could cover your power if you did. I am building a lithium and hope not to dip past 50% the first day, so that I can have enough to make it through a cloudy day and run the generator to charge when I need to.

You talk about getting more panels, but with mine I get about 18 watts per 100 watt panels on a cloudy day. With buying 1000 watts of panels and I would expect you to only get only about 800 wh from all those panels, or 15 to 20 amp hours at a 48 volt battery.

To me since you already have the system installed, if you're done charging the batteries early on a sunny day, its time for more batteries, and if you are not getting enough charge, you need more panels.

 

[BenQ]

12 more panels at 280w on the midnite classic would be a way better route than 5 panels at 195w.

 

[Greendream]

We figured the usage calculations based on the house but with 2 AC units running in campers its sucking all the energy so the calculations are out the window for the next couple months. I am sure once the house is finished we'll have more power than we need but for now it seems like we gotta get more panels. Another battery may help but we'd be depending on a cooler sunny day to top off the charge.

I'm going to get 5pc more of these 195W panels. I can recoup the cost of the midnight classic and not have to invest in more wire.

 

[Hedges]

4kW of PV.
Are they all oriented the same direction? Is battery full middle of the day but draining later?
Consider two arrays oriented 10:00 AM and 4:00 PM sun. You can put 40% more PV wattage on the charge controller, and power will be spread out longer over the day.

"Overcast". How much power is being produced? Overpaneling can help with that, but only somewhat. At some point, you have to rely on stored power from when there was good sun.

Shade for the trailer.

 

[BenQ]

We figured the usage calculations based on the house but with 2 AC units running in campers its sucking all the energy so the calculations are out the window for the next couple months. I am sure once the house is finished we'll have more power than we need but for now it seems like we gotta get more panels. Another battery may help but we'd be depending on a cooler sunny day to top off the charge.

I'm going to get 5pc more of these 195W panels. I can recoup the cost of the midnight classic and not have to invest in more wire.

Good luck with that!

 

[12VoltInstalls]

It would seem at 48V you have “just enough” battery. For 10-12kW/24x7.

But it’s not doing it for you so…

First: what the heck is sucking the power?Is your onboard converter disabled? Fridge on propane or resistance electric? Or traditional electric? Electric hot water heater?

if the leaches are eliminated then you can figure out where you’re short elsewhere- and maybe know if you need more juice

 

[time2roll]

Yes if powering an RV make sure everything possible is running on propane. Move them under some shade would help.

 

[Greendream]

It's 2 AC units sucking all the power. We draw between 3-9 amps with our normal load, and over 55A with ACs running. There is no natural shade, available at the campsites so we are the mercy of cool weather or clouds.

One of the campers has a propane fridge the other has electric. Range and ovens are all propane. Everything else is fairly efficient. Seems like a waste just for AC. I'm hoping the extra panels will have other benefits.

 

[12VoltInstalls]

So without sun for 12+ hours/day my ‘just barely” comment above is at least 50% wrong considering 55A of load continuous for probable 10-12hrs per day.

Just a ball -cap thought on the KWh and if you have a full sun day I’d guess the battery goes dead 3 hours after dark or sooner.

5 more 195W panels aren’t going to fix this. That will make almost 5kW but you have 6.5kWh problem to solve if everything was going to be 100% of label. But you have to both make the power you’re using snd make enough on top of that to charge the batteries. So even at 1/3 load after dark you’ll need like 2.5kWh from batteries.

And the battery as stated above is “seriously” undersized.

 

[time2roll]

Probably need 2x solar and 3x battery. Or a generator.

 

[Wibla]

I'm going to get 5pc more of these 195W panels. I can recoup the cost of the midnight classic and not have to invest in more wire.

This won't solve your problem, you're trying to piss on a fire.

You need way more solar, and you need to orient some of that solar in such a way that you get more energy in the morning and afternoon. That means sub-arrays aligned towards south-east/west.

 

[2009Bounder2020]

Get a generator if you think your current setup is all you need once the house is done.
your battery is way to small, my rv with 2 ac units would not work with what you have, not even close. you need about 3 to 4x the battery capacity

 

[callsign4223]

I'm with the generator folks. This is a 2-3 month problem. Even if it takes another 6 months to build the house the summer will be over in that time frame and with it the huge a/c loads. If you truly did size the array properly for the house when it's done there is no reason to spend thousands on extra panels when you can spend $400 for a 4kw generator to supplement during the hottest parts of the day. The generator doesn't have to carry the entire load of the RV's, it just has to bridge the gap you currently have. And bonus, you have a generator for future use if something breaks and you're waiting on parts.

 

[Wibla]

If you truly did size the array properly for the house

I doubt that, to be honest.

 

[mesquito_creek]

If you are running rooftop coleman type RV AC units, make sure the airflow is maximized by checking all the duct work and cleaning the coils etc... There are lots of youtube videos on common problems with the installs from the manufactures of rooftop AC units. Make sure they are cycling on an off. If they never turn off you are over cooling or underperforming.

I have almost the same system. 412 ah @ 48V with 4000 watt PV array.

I have a large RV with 2 - 15000 btu coleman AC units. I can run both AC no problem during the peak PV production from 11am-4pm. With the units cycling on and off I can even put a little bit of energy into the battery bank. But after that I only run one unit at a time. I have a standard residential fridge on top of that.

I will add that I am in Southern Utah and make solar power from about 8 am until 5 pm with about 6 hours of near maximum production.

When I am not there i leave the fridge full and running and 1 AC unit set at 90 degrees F and for the most part my battery bank is able to reach full SOC daily and really doesn't drop below 50%

 

[callsign4223]

If you are running rooftop coleman type RV AC units, make sure the airflow is maximized by checking all the duct work and cleaning the coils etc...

I saw a video of something that seemed to address the airflow concern.
Turbo-Charge your RV AC with RV AirFlow! (40% Improvement on Average!) - YouTube

and a link to the product itself
RV Airflow Systems

 

[mesquito_creek]

I saw a video of something that seemed to address the airflow concern.
Turbo-Charge your RV AC with RV AirFlow! (40% Improvement on Average!) - YouTube

and a link to the product itself
RV Airflow Systems

I did not buy the product, but I did my best to correct all the poorly installed duct work, foil tape blocking the duct work and the mis-aligned separator between the output and intake etc... I noticed much better air flow and my unit started cycling more reasonably and reaching set temp faster!

P.S. I live in Arizona and I probably keep my temps higher than someone from different parts of the country. I set my t-stat at about 80 degrees during the day and 78 at night. My dogs also live a warmer lifestyle than most (OP mentioned all this was to keep his dogs cool)... LOL... I would have zero issues with my dogs roughing it at 85 or so in the RV or shade with plenty of water. My dogs are free to stay outside in the summer and they choose to regularly.