Newbie

Floffgridfarm · April 2023

Good morning everyone, ive been somewhat of a lurker hoping to gain more knowledge about being fully off grid. I purchased an off grid system from someone who designed and built it himself. Very smart guy and hes been more than helpful in helping me along the way even after purchase. I ran this system on a travel trailer for roughly 2 years and didnt have any major issues. Recently power was moved to the house. Initially i did not notice any issues but i wasnt staying there. only working on house in day time.

one cloudy day i had the led lights on and noticed it was occasionally flickering like a surge. Couple days later it was still happening and noticed with a tv plugged in it was enough of a surge to turn tv off but only for a second. 100 percent off grid, 48v nissan leaf battery pack, aims 120v 6000 watt inverter. Tristar MPPT, midnite solar combiner box. roughly 2.3kw of panels. Has anyone else experienced this? any ideas on what could be causing it? it doesnt appear to be affected by load. meaning fridge will cycle on and off and that doesnt cause the flicker. It is just random, sometimes 5 min apart sometimes over hours. with voltmeter in house i notice sometimes it drops to 110 but ive seen a few dip into the high 90s for voltage.

any help would be greatly appreciated.

thank you

Dave Angelini · April 2023

I would load test it with a 1500 watt heater, maybe 2 of them. Monitor dc voltage. Any additional info you add will be useful.
Florida is the lightning capital ! Tell me it is not in Tampa/St Pete...
You should have surge protection on solar and your AC loads. Probably also on your DC input to the Inverter.

What does the person who sold it to you say?

Floffgridfarm · April 2023

I am further south and inland of St pete but not by much, closer to the punta gorda/arcadia area. I will try and put a decent load on it and see what happens. thank you! The gentleman i purchased it from thinks it may have something to do with the inverter internally.

Floffgridfarm · April 2023

And as far as surge protection, i dont have anything really. I finally am getting the house finished so i recently finished moving all of the solar over to the house. I would like to hear everyones suggestions on what they use and recommend.

Floffgridfarm · April 2023

Okay update for anyone interested

I put a toaster and an air compressor on and AC side dropped from 120 to 117V. In my opinion, acceptable. On the DC side same test, dropped from 55.3 to 55.2. Still acceptable. So I hooked volt meter into outlet inside battery bank cabinet and noticed it is when the inverter kicks on its internal fans that the voltage sags like that. I have contacted aims and they said to test like you had said to verify. They seem to think it could be internal components going bad inside inverter. I have since put a box fan on the ground with cabinet door open, still inside a shed with that door closed and it has not surged since. I have a feeling it is being caused by heat and possibly it overheated one time. I never had the inverter shut down from heat and ive never seen an error for it but thats where i am leaning towards. I will try to add some fans to the cooling vents on the inverter to see if that fixes the issue. if it does then obviously the internals do have SOMETHING wrong. Could it just be one fan drawing too many amps becuse its on its way out?

BB. · April 2023

I have had many computers with DC fans in them... And of the hundreds (thousands?) I have run across--I have seen them in three states: Running, Dead, and one generating so much electrical hash it degraded the analog/digital communications circuits... Other than using a scope+wire loop antenna, that fan seemed to also have a "browned" label on the back of the fan from running hot.

Regarding your system... It certainly sounds like your inverter may have issues running warm/hot. In general, power electronics need to be kept cool for a long life--The engineering rule of thumb is for every 10C (18F) over room temperature, the "device" will age 2x faster... So keeping the electronics cool is a good idea in any case--And is certainly possible that if your inverter is now running cooler, it may be running "better" too. Conversely, running 10C cooler, 2x longer aging life...

Checking for "real bugs" (i.e., insects) and dust inside the inverter. These can cause issues inside the control circuits--especially if you have any condensation (creating variable short circuits). In general, there is little owner serviceable components inside an AC inverter (outside of DC Input fuses in some inverters.

Screens and filtered air can help in open environments.

Regarding surge suppressors, our host sells these from Midnite Solar. They are actual MOV (metal oxide varistors) vs sand filled spark gaps (in many other types). Much more reliable in surge suppression:

https://www.solar-electric.com/search/?q=midnite+surge

https://midnitesolar.com/products.php?menuItem=products&productCat_ID=23
https://midnitesolar.com/documents.php?productCat_ID=23&model=MNSPD-115&product_ID=283&act=info (documents)

SPD (Surge Protection Devices)

-Bill

Floffgridfarm · April 2023

Thanks Bill,

after some tinkering around today trying to test best method for cooling, i have not defeated the box fan yet. My issue im having is that the county wants everything to be nice and tidy in terms of engineering and up to code snuff. I have no problem with that as i dont want to hurt me or anyone else either but with that being said, i have all of my components inside of a traffic cabinet, roughly 4' tall. 2.5' deep 3' wide. It did great in this when it was outiside with a roof over it in terms of heat.

I had to either pay to have that engineered or just put it in an engineered shed, it was cheaper for an 8x8 engineered shed than it was to pay an engineer...

So now i have the cabinet inside of the shed and that must be making it work that much harder to vent off excess heat.

Ever since yesterday having left the box fan on it, i dont hear the inverter whirring like it used to and i havent had a single surge so I would definitely conclude it is an overheating issue. I am going to try and come up with another way to use vents and fans if i can as i do not want to have to put an AC in the shed as my battery bank barely handles the house right now. I will definitely be looking into the the links you posted. Thank you both for the help! I hope this helps other people as well.

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