Inverter shows overload at only 30% Load

the_uglydog

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Hi Everyone! I have a 10kw Aims off grid inverter. When I first installed it May 2020 it wouldn't load over 40% and would shut off with an overload alarm, on it's control screen the AC voltages had been reading about 20-50 volts below what was actually coming in from the utility, tested at the input terminals, I posted about it here before. The problem went away by itself and it was working perfect since July 2020. It would carry it's normal load of 20-40% with short term loads as high as 90% with no problems. The breaker on the unit for solar/battery input is 120amps DC, the utility output is 80 amps AC. At 40% the DC tests at 45 amps DC and the AC load tests at about 25 amps AC, at 90% the the DC tests at about 80 amps DC and the AC tests at about 50 amps AC. It is set to wide range for AC input 173-260 volts AC, and acts the same even with the utility feed shut off. Well in May 2021 the problem came back after the 1st typhoon. It won't carry a load over 29% and the input voltage readings were low. I had it repaired (defective electronics) and it reads the correct voltage now, but it still won't load over 30% very often. I thought maybe there was a problem of the wiring getting wet so I tried turning off the utility input, each of the breakers in each combiner box one at a time and one box at a time and different output circuits but it doesn't matter, 29-30% it shows overload and shuts off. Has anyone run into anything like this on any brand? Any suggestions on which component could cause this on any brand unit? Could one of the relays cause this? Any thoughts would be appreciated. That's about it. the dog
 

MrAubin

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I read your other post and I'm no engineer but it sounds like the inverters own thermal sensor is haywire and is tripping early. Maybe a programmed safety if the temp sensor is damaged. Maybe an internal connection inside shrink tube no one has seen is corroded. Did you say of you had a flir or not ? My blackview BV9800Pro has one very handy for tracing hot spots. That's sh!try those are expensive inverters and no inverter company seems to have either big inverters or good maintenance warranty's. I'm currently looking for an inverter and am at a stand still finding a " good " one.
 

Hedges

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I'm currently looking for an inverter and am at a stand still finding a " good " one.

What is your budget?
There are definitely good inverters available.
"Good, pretty, and cheap ..."
 

MrAubin

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No budget as I'll buy it the following tax time most likely. 5k dollar Cad roughly. But need a 24 volt 2-3000watt. I really want a GFCI receptacle built in for extension cords. Also probably consider a 6000 watt split phase later. But I really like the look of the aims. Blue or white or green body. I know I can't choose and I can always wire wheel the body shiny later. But ya thanks for any insight. Cheers Steve.
 

Hedges

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Is that for mobile application, so automatic switching of neutral/ground bond depending on availability of shore power is desired?
24V is sufficient for that wattage. 48 allows higher power, less current and voltage drop at battery.
There are some interesting low-priced hybrids like GroWatt, don't know how good. I think one is $800 for 3kW 24V.

The ones of known quality include SMA, Outback, Midnight, Schneider, Victron, a few others.
I use SMA for a big heavy whole-house system. They used to have lower wattage lower battery voltage models in Europe, but I don't see those on their website anymore. Sunny Island is $5000 MSRP but $2500 street price (reseller liquidation in US) for 6kW 48VDC 120VAC (in US; 220V 50 Hz rest of world).

What you should get depends in part on what you need to power. Induction motors need 5x surge to start, other loads like inverter drive mini-split may have no surge at all.

You can always get a cord with GFCI. Those should be two-pole not one pole, because can never know when they'll be plugged into an outlet that is wired backwards. Or build your unit with a couple boxes wired together.
 

MrAubin

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Not a mobile system. Be at home but separate from grid. I know how to lightning protect, and earth, so I'm not worried there, I know about only tying in the neutral once, I want to start by seeing how many 500 watt things I can run through the summer and try to power an infrared heater inside in the winter my base boards are killing me in the winter. Also I have an amazing 8 hr window of direct sunlight in my back yard. Couple day break guess I'll dive into those inverters again. Just ordered 4 more roles of wire, hydraulic crimper. Lmfao, Every day I'm purchasing. Cheers
 

Hedges

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Consider hot water radiator baseboard heaters and a hot water tank. That may be a more cost effective way to store sunlight for nighttime heat. Depending on ambient daytime temperatures, a heatpump water heater might perform better.
100W electric blanket if you want to save power!

As a fixed installation, you can hang electrical boxes and GFCI off it.

Consider going 48V. That has greater potential for future expansion.
Could be GroWatt or Deye would be a decent economy choice.
Some of the others for premium brands.
If you are in the US or within reasonable shipping distance, the liquidation deals on SMA Sunny Island are arounds 50% of MSRP. Not cheap, but very capable. If you would want to expand into the 6kW to 24kW range, then a good choice.
 

MrAubin

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Would be awesome if I didn't rent a townhouse sorry. The most I can do integrally is switch off the breakers in my units sub panel and lock off each switch with a breaker lock and plug an inverter into a recepticle to back feed. That's why I want recepticle outs on my inverter. And the glory of multiple systems is yes again my second system would probly be a 48 volt as I don't own my own home yet I am not trying that hard yet. This is my first build. And I'm not happy with the wall I have to mount it all on, damn window..... Cheers.
 

Hedges

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I don't recommend using a suicide cord as you're considering. Risk of blowing up your inverter or electrocuting utility workers.

If you want to backfeed house wiring, get an interlock for the breakers. But then you would be trying to power the whole house.
There are units specific to each model. One example:


Grid-tie zero export could be another option. Inverter synchronizes to the grid and backfeeds, but not more than what house consumes. This doesn't provide backup in case of power failure, but would shave consumption from grid when operating.

Or a transfer switch. A non-kosher way would be to cut an extension cord in half, wire the female to breaker in panel and male to the wires going to a circuit. Plugged together, it is grid powered. Plugged into an inverter, it is off-grid. A 12 awg cord should be used for a 20A breaker.
 

MrAubin

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No if I sent power to my wall and turn that circuit off it will only back feed that circuit. And someone would need my key to turn the breaker back on. But that's not my plan I just want to be able to plug one thing at a time then maybe 2 depending on what I pull then I'll determine the next system. Everything I use that draws is in my kitchen dining area so it's easy to plug something in use it and put the cord away I stay home with my autistic son so I need these things to keep busy.
 

Hedges

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The padlocked breaker (LOTO) would be pretty effective in keeping that circuit disconnected from the grid.

A suicide cord to backfeed an outlet from inverter means electrically hot exposed pins, which is a hazard especially if with a vulnerable individual present. GFCI may or may not provide any protection - the hot and neutral pins can shock and wouldn't trip GFCI.

It is better to have a female socket with power available, and male plug to receive power. Generator inputs do that with a transfer switch. If you disconnected the branch circuit either at the breaker panel or at one of the circuit outlet boxes, you could have a male plug available to plug into inverter and no hazard of exposed live pins.
 

MrAubin

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Yes I wouldn't want exposed hot prongs either I'll make heavy cords that reach the devices I want to run while I want to run them. Currently I'm concerned about my planned bus bars as I don't need my son connecting them..... Soo much to think about. But I've got till next march to complete that's my make believe deadline. Hahaha.
 

the_uglydog

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I read your other post and I'm no engineer but it sounds like the inverters own thermal sensor is haywire and is tripping early. Maybe a programmed safety if the temp sensor is damaged. Maybe an internal connection inside shrink tube no one has seen is corroded. Did you say of you had a flir or not ? My blackview BV9800Pro has one very handy for tracing hot spots. That's sh!try those are expensive inverters and no inverter company seems to have either big inverters or good maintenance warranty's. I'm currently looking for an inverter and am at a stand still finding a " good " one.
I have 2 Musts, very cheep, one made by New Green Tech, that I haven't hooked up yet and one Growatt plus that POS Aims. Of all of them I like the Growatt the best. It is by far the easiest to connect the wiring to and it's totally sealed, weatherproof, doesn't seem to be effected by the heat here and with the connections in a large sealed box on the bottom. I had some problems setting it for the wide voltage ranges we get from the utility here, and one of their engineers set it for me, they answered EVERY question I asked right away and helped with any issues right away! Their Shinelink connects the inverter to the internet so you can monitor it from anywhere in the world. If I can't get the Aims to work once the repair guy here replaces the last couple of parts he says is the problem I'll try to get a Growatt that doesn't have built in charge controllers as I like to use about 50% more panels so we have full power longer during the day and when it's cloudy. I'll check on the Flir. We have mostly all our own infrastructure here, electric, water, cell, so it would probably be a big asset to have it. I use a cheep temp gun now, it helps a lot, but Flir would be better.
 

the_uglydog

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No budget as I'll buy it the following tax time most likely. 5k dollar Cad roughly. But need a 24 volt 2-3000watt. I really want a GFCI receptacle built in for extension cords. Also probably consider a 6000 watt split phase later. But I really like the look of the aims. Blue or white or green body. I know I can't choose and I can always wire wheel the body shiny later. But ya thanks for any insight. Cheers Steve.
Based on my experience with Aims all I can say is "I will NEVER" buy another! I don't criticize things very often nor recommend NEVER to buy something, but I have to make an exception with Aims, they totally deserve to never have another sale.
 
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