Solar Power

Chris0nllyn

Well-Known Member
Just an FYI for anyone using a 12VDC to 120VAC inverter. They all have a 3 prong outlet (hot, neutral, ground) but the ground is not connected to a real ground. If you use one in damp conditions where you'd normally use a GFI circuit breaker for protection, a GFI cannot work and there is no GFI protection.

I came across this out of curiosity, used a GFI tester on the 120VAC output, knowing it was going to be used outside in potentially damp/wet conditions. GFI tester showed no ground circuit. Tried 2 other inverters, same thing. There is no "earth" grounding. The inverter frame is "grounded", but only to the negative pole of the battery.

A ground isn't needed for a GFCI to work property. It senses current on the neutral and trips.

That's why old two-prong (ungrounded) outlets must be swapped with GFCI outlets or breakers.
 

Chris0nllyn

Well-Known Member
I have a spare full size fridge, top freezer, just sitting there. I got curious if the solar system could power it, so I hooked up the watt meter. Again, surprised. Initial turn-on surge was about 1500 watts, but quickly fell to 120 watts. In partial sun, the solar system can easily cover 120 watts. After it ran for a few hours, it fell to 95 watts. Barely more than the freezer/fridge I put together. But being bigger, it will run much much longer. During the day, not a problem, but it would need a much bigger battery than the 45Ah I have now to carry it thru the night.

So, in a pinch, the little, portable solar system could run a full size fridge. Interesting.

I came across this thing recently.

Dometic powered cooler with a fridge side, freezer side, and optional deep freeze. The biggest model only uses 0.85Ah/hr @ 12VDC (or 10.2Wh).
Looks neat, but probably more expensive than your whole set up (it's about $1,200).
https://www.dometic.com/en-us/us/products/food-and-beverage/coolers/electric-coolers/dometic-cfx-65w-_-152179#specifications
 
I've looked at many of the 12v fridges, and they are all very expensive for what you get, which is why I thought it was a great thing to build the one I did. Cheap, and works better.

Regarding the GFI, ok, I've been educated. Did a little research on GFIs and you're right, it senses a mis-match between hot and neutral output vs input, not ground. It's called "ground fault" not because the ground has faulted, but because the hot has most likely found a path to ground. Given that, I'm going to add a GFI breaker to my setup and re-test. I'd feel a lot better with an operational GFI when outside.
 
Well, contrary to the manufacturer of the inverter, a GFI breaker between their inverter and my 120VAC hardware works correctly, as intended.

Have to modify the case a bit to accommodate the GFI as it's bigger than the duplex outlet I have in there now.

Thanx for the heads up, Chris.
 
Replaced the outlet with a GFI, mounted up the solar charger display and remote on/off switch for the inverter.

Other than building a stand for the solar panel, this is pretty much a done deal.
136677 136678
 
Couple of updates... I have been using a 45Ah battery for this project, but it's really kind of small. After much looking and thinking, I ordered a 100Ah sealed AGM battery. This will give me more than double the capacity and still be able to be fully recharged during a normal day. I originally wanted a LiFePo4 battery, but they can be fussy, require periodic maintenance, and way expensive. I can replace the AGM if it fails and still be ahead on cost vs the LiFePo4. Just have to mindful of not draining a sealed battery beyond 50% or you can permanently damage it. The more capacity, the less likely that will happen, but too much capacity and they may not fully recharge during the day.

While waiting for the new battery, I'm making some minor fixes. The switches easily pulled apart, not very robust. Since they will (or never should) be opened, I decided to epoxy the switches shut where they come apart. No more worry there.

I had used some 4 gauge wire for interconnects, but it was THHN which is pretty inflexible. Upgrading all of that to a very flexible 4 gauge. Best price I could find on wire was to buy a set of 4 gauge jumper cables and use that wire. That will work out well. Started de-soldering all the original connectors, but have to use a blow torch to make these. I like soldering better than crimp for wire this size, and since the connectors are not cheap, I can re-use them. Once you crimp a connector, it cannot be re-used.

Also going to add a battery expansion port to easily add another battery if needed.
 
Finished all the changes except the battery expansion. Need a couple of feed-thru battery posts, didn't have any. All the stiff wire was replaced with flexible wire. Remounted the inverter making the wiring a bit easier, and also gave me access to the USB charge ports on the solar charger, so I added a USB charge port. It's all ready for the new battery, hopefully the end of the week. Free UPS shipping on Amazon for a 60 pound battery. Can't beat that.
Before:
137674

After:
137675
 

PeoplesElbow

Well-Known Member
Just have to mindful of not draining a sealed battery beyond 50% or you can permanently damage it. The more capacity, the less likely that will happen, but too much capacity and they may not fully recharge during the day.

One thing that has been discovered in the last 20 years or so is that if you don't use the full range of the battery (ie not charge to 100% and discharge past a certain point) that they last much much longer. So I wouldn't worry too much about your battery not getting a full charge.
 
Agree, having read all those tests and charts. If I'm drawing current overnight and there is a chance I'll deplete the battery, I'd like to start off the evening with a full battery. If it's not fully charged, it could deplete sooner than I would like.

But again, with the 45Ah battery, I was able to run the fridge for 24 hours. With the new battery, I might be able to go for 2 days with no recharge, so starting off with a full battery becomes moot.

The new battery will be here today. I'll set it up , peak the battery and see how long the fridge can actually run with no charge input.
 

Gilligan

#*! boat!
PREMO Member
If I'm drawing current overnight and there is a chance I'll deplete the battery, I'd like to start off the evening with a full battery. If it's not fully charged, it could deplete sooner than I would like.
Watch shorter porn movies. They all end the same way anyhow...
 
Top