Might have blown fuses

hillside · September 2022

...on the Samlex PST 3000-24..I turned it off a couple of nights ago as it had been 2-3 cloudy days in succession, after disconnecting the full size refrigerator (the only thing we'd been using it for)..I had done that a couple of days prior and had no problem.
(This install has been operating for 7 months perfectly.)

Next morning, with no load on (frig connected to municipal power) I turned the inverter back on and...nothing. Voltage from the panels to the batts. is there but inverter has no power.
Then today I was checking the breaker in the red pos. cable to the inverter and it is open at either setting, that is, power feeds to the inverter in either position. It is like this:
https://www.ebay.com/itm/281449588568
Someone here had recommended a quick blow fuse but I couldn't find one anywhere. Out of stock here as well. So I went with the circuit breaker, which takes 2-10 seconds to trip according to the company.

So I just ordered a new Cotek 2500W inverter from the store here in case this Samlex cannot be fixed.

In our downstairs room we have had a Cotek 3000 W operating for a few years and the installer at the time used a 300A car stereo type fuse/breaker and with the same batteries, etc. and it has never had a problem.

What should I use for a fuse? Is 200 Amps enough? (4- 370AH L16's)

hillside · October 2022

First time I've never gotten a reply...
It appears there are as many as 8 or 9 20 amp automotive type fuses inside this inverter, and they're soldered to the board.
How difficult would it be to open it up and replace them?

BB. · October 2022

The first question is why did the fuses blow... Typically, there is an internal fault in the control hardware for the H bridge transistors. A typical failure is the drive electronics turn on the "wrong pair" of transistors at the same time and create a dead short across the battery bus--blowing the fuses.

Just changing DC bus fuses won't fix that.

-Bill

littleharbor2 · October 2022

Not saying the breaker is the problem but are you sure you want to trust all your equipment as well as the structure it is housed in to an $8.00, 200 amp breaker? Get a T-class fuse or heavy duty DC rated breaker.

hillside · October 2022

I couldn't find the T class 200A fast blow fuse anywhere, even here.
Finally located one at Platt Electric and will put it in today. A friend has a similar setup with no fuse at all and has no problems, go figure.

hillside · December 2022

UPDATED,
It was not a fuse internally and it wasn't the 200 amp circuit breaker. It was humidity that killed the inverter. I mounted it outside the house so as not to hear the internal cooling fans which are on 70-80% of the time. We still hear them with the new Cotek 2500W replacement but that one is doomed also since it's in the same location.
Turns out, living in a high humidity area like the Caribbean turns the insides to iron oxide in as little as 6-7 months. So, I'll move it inside where it will make our house a noisy factory and will rust out in short order.
We are 9 miles from the ocean and 700' altitude but salt air permeates everything on an island. And relocating it inside won't help other than helping it live a bit longer as the humidity/salt air travel everywhere. No AC, so doors and windows are open always and remote as we are, screen doors are open at night even.
I refuse to go to the next level with a giant array and power wall batteries that some friends have. I could have paid for our grid electric monthly bills for years to come for what we've spent on solar equipment so far.

Image: https://us.v-cdn.net/6024911/uploads/editor/22/7vtrax4mazu7.jpg

Should I put sound deadening material around the next one for noise reduction? Maybe a Coleman cooler cut open at each end?
Not sure if it'll help much.

BB. · December 2022

Working on a house is on the (wet/cold/foggy) coast near me... The owner avoided heating and ventilation. Besides a terrible case of mold on the walls and ceilings, the condensation was so bad it shorted out the breaker panel in the home (arcs to the 120/240 VAC buses) and even took out the local pole transformer (with probably had its own wet/salt issues). Temperature cycling, high humidity, etc. are always killers of electrical equipment.

In my very limited shipboard electronics experience... Sealed enclosures with a drilled small weep hole at the low point/base of the enclosure--Because humidity always get in somehow and needs to get rid of any condensation buildup.

A friend of mine goes to auctions sometimes and finds weather/water resistant enclosures (heavy steel, gaskets, etc.)... If you could find a largish metal enclosure, it could help keep your electronics dry without overheating... May also help reduce fan noise (again, watch internal temperatures, need for heat sinks, etc.).

-Bill

Dave Angelini · December 2022

It does not look like the electronics are conformal coated. I really can't tell but if you live near the Ocean it is a requirement if you want it to last.

Ocean cruisers often have this problem. The electronics I use from Schneider and Outback have the coating BTW. They also offer closed cooling to keep the dust off the electronics.

hillside · December 2022

Scrolling through the Schneider items in the store here I don't see anything that would fit my system. Keeping it basic, 2 pairs of 450W panels with each pair using a 40A controller to a 3000W Samlex pure sine inverter (currently using a 2500W Cotek) and 4 L16 370AH batts. Only using it to power a full size fridge and a propane gas oven (with electronic controls).
I'm surprised they don't weather proof these things better.

Photowhit · December 2022

FWIW - I used a Prosine stored outside in sonly slightly protected areas. They are popular on boats and do have a conformal coated, as does the Magnum I replaced it with.

In theory it lasts a very long time, but can make it a pain to work on.

Conformal coating - Wikipedia

hillside · December 2022

Photo, reading the link makes we wonder if that's a DIY project?
It mentions silicones or urethanes as possible coatings.
I have a new, in the box 3000W inverter and is that possible?

BB. · December 2022

A nice website about Conformal Coating materials and processes:

https://www.chemtronics.com/the-ultimate-guide-to-conformal-coating

Is this DIY? I would tend to avoid this for more complex things like AC inverters...

You have cooling issues, and possible changing of capacitor values in FET Driver circuits, etc... The coatings may alter the capacitor values enough to cause issues (just a concern, I don't know).

I would be looking for old "outdoor rated" used metal electrical cabinets as my first choice. I am not sure what is available in your area, but it would be a start.

You can find some at Amazon too:

https://www.amazon.com/s?k=outdoor+electrical+enclosure+nema+steel+or+metal

With larger inverters... There is still the issue of heat. A 3 kWatt inverter with 5% losses generates 150 Watts of heat. A smaller enclosure may run too hot if you are heavily loading the inverter (have a filtered fan run when hot, use extra aluminum heat sinks inside/outside of box for more heat transfer area, etc.)...

-Bill

hillside · December 2022

Thanks, Bill, at this point I'll wait until the new Cotek 2500W I bought at the store here fails.
That will give me some time to figure the next step. Heat, and humidity with salt in it are the issues...inside the house is the likely place but there's no stopping the humidity without AC. Luckily in these winter months humidity is much less.
Anywhere in the southeastern states near the coast must deal with the same thing in the summer.
Or, Galveston, anyone?

BB. · December 2022

Born and raised on the coast below San Francisco... Keeping phone service was always hit and miss (talk for a bit, hang up, dial again--For some subscribers).

1970's American vehicles (especially GM)--Those things would turn into rust buckets in a handful of years (rust right through the body panels).

-Bill

hillside · December 2022

So I've decided to move the current (pun) inverter inside the house to prolong what life it has left. It's about 3 months old.
Now, do I need to bring both controllers in also? Both are Renogy MPPT 40 A and have been outside since this array went up about 7 months ago.
It's a bit time consuming since the house is concrete block with 3/8"-1/2" coating so drilling holes through it takes some time. Then drilling holes inside to mount everything.

Happy New Year!

Dave Angelini · December 2022

You have to protect the gear either by bringing it in, or building a space that is protected.
I think Bill linked you NEMA rated outdoor enclosures. Problem then is the fan bringing dust in. Dust and moisture are as bad as salt alone.

All three are a disaster or whatever you call losing power offgrid. Some people just say they will light a candle. I call it a disaster😉

hillside · January 2023

After talking to a couple friends that have solar arrays here, I've decided not to move the stuff indoors.
Humidity in the air here goes indoors as much as outdoors as it seeks a balance. It won't make a difference in this tropical environment.
If I put the inverter into a protected space I have to allow for air flow to the fans, and then summer heat becomes an issue.
Everyone has lost electronics here and it doesn't matter where they are. Mine are in the shade, under a weatherproof canopy out of the wind, etc. Their lifespan won't be prolonged by moving them indoors, where the moisture levels will be the same. One concrete wall won't make a difference with windows and doors open 90% of the time.
I will look instead for conformal coated inverters but so far there are none available. Must be supply chain stuff.
Thanks for the replies, they're all appreciated.

Might have blown fuses

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