Energy Matters Forums

[Andy4123]

Hi folks. New to the forum and hoping for some help.

I have an off grid property with a generator and a solar/battery setup running the fridge and satellite internet. There is a separate games room and shed which is wired to a caravan style inlet plug, and also a donga which is also wired to a caravan plug.

I have setup a small solar system to run the donga and (hopefully) the games room/shed. The system consists of 2 Aldi 170w panels connected to a pair of deep cycle batteries. I have a Zenot 600w pure sine wave invertor with a 10m lead to the caravan plug on the donga. I have replaced 3 (of the 4) fluoro tubes with LED tubes (the 4th one broke on the way).

The setup more or less works but it tends to trip the invertor at random times and I can't for the life of me work out why. The LED tubes are only 9w or thereabouts. Last night it ran all night with one tube on but then tripped early this morning. Other times it will trip after a short time, sometimes even with everything turned off. Same with the shed - will run the lights for a bit but then trips.

When its running the inverter is barely working - still shows standby, i.e. < 20% load. Battery voltage is stable at around 13.8 - 14.5 while charging and doesn't noticeably drop. I found that it had trouble with 2 old style 40w globes - light dimmed a couple of times when the second one was turned on then it tripped.

The inverter beeps when it trips and the book says what the beeps mean (2 and 3 for under voltage, 4 for over voltage, 5 for overload). When it trips it seems a random number of beeps, sometimes 2, 3, 5, 7 followed by 11 beeps.

On paper the inverter should be well up to the job but when connected to all the wiring in either the donga or the shed it can't even handle it when nothing is turned on. Maybe the inverter is faulty but trying to prove it is difficult. It seems to work ok with something just plugged directly into it.

I am hoping someone might have some ideas. I have tried so many different things to try and isolate it and really gotten nowhere. Fingers crossed.

[jaahn]

Hi Andy
I am no expert but perhaps your little system may have a safety problem. Small inverters are not designed to be supplying power to a fixed wiring system unless certified The wiring setup may not be suitable to give safe operation. You should be careful. You should really only operate items direct from a stand alone inverter and it has no earth.

Old style fluro tubes have very poor power factor operation and they kill inverters. The square wave inverters just die straight up. Due to the low power factor they draw lots more current than their wattage says. It is inherent in the crap design so just do not use them on a small system. Use LED bulbs, cheap to get online now.

Having no idea who did or how the wiring of the donga was done, my suggestion would be to get an electrician to check it out for your safety. You only die once. 240V from an inverter is as lethal as from the mains or a generator and has no safety features like a normal house system.

Sorry to be so negative.
Jaahn

[jules]

Hi Andy,

I'm not familiar with the inverter you're using but smaller devices like that one are generally best suited to basic functions where you might be running one small gadget with short and direct wiring.

If you're planning on running a small shed/donga with a fridge, a computer, modem, lights plus a few other small items you would probably be best off to work out a strategy to incrementally increase the size of your system by selecting components that can either be increased in number, like solar panels, or have the quality and capacity at the time you buy them to take extra power at a later date.

It's possible to pick up a lot of used solar equipment in good condition these days as people upgrade their old, smaller systems. Just as an example, I picked up several 250W solar panels in good, tested, used condition for $50 each over the weekend.

As far as analyzing the problem, you might need to tell us what you've tried so we know what not to suggest but maybe you can remove all the 240V out connections and gradually add them back to see which specific one causes the problem. The 10m of lead plus the other wiring could well be too much for the inverter.

Other than that, I agree wih Jaahn's comments about safety and risk.

Jules

[Andy4123]

Hi, thanks for the replies. Safety is certainly uppermost in my mind so starting to reach the limit of what I can try. I have done some more tests on the inverter in a more controlled environment and I'm fairly convinced the inverter is fine. Problem is I really only want to power a few lights so going to a bigger system is really not necessary and in fact even 600W is overkill for the usage.

I'm now back to thinking of converting it to 12v (or maybe 24v) but now I'm finding such a limited supply of components compared to AC. Lights, switches, breakers, etc. And so much more expensive. My thoughts are:

1. replace the ceiling lights with low power 12v LEDs
2. reuse the internal wiring and switches making sure total current draw is < 10A total as the lights are on a single circuit. Each switch would only be handling < 1-2A
3. Run a thicker guage wire from the battery to the power box to connect into the existing wiring.
4. Appropriate fuses/breakers.

Q. I'm thinking I would need some sort of voltage regulator to keep it close to 12v when it's charging, or are LED lights generally tollerant of going up to 14.5v? Also need some low voltage protection in case the battery runs down. Any suggestions?

[jules]

24V would be better from the perspective of wire thickness.

Your fridge can run 12/24V?

Plenty of reasonably priced 24V LED lights from places like:

https://www.12vmonster.com/

A regulator is definitely needed. I've used Fangpusun for smaller jobs and they've been very reliable over a number of years. I hadn't realized at the time I bought them that they are a knock off of a rather more expensive German brand but they seem to have done the imitation very well.

Use heavy gauge wire wherever you can.