2015 03

2015-03-07

I wired up the transfer switch and the inverter today. I was running from the inverter for several hours today but I have a problem with the AC output being too low. I can't seem to get it to output more than 90VAC.

I need to call Tripplite support in a few days to find out what is going on. I don't like running my appliances from 90VAC.

I tested my espresso machine and the microwave oven which seems to work just fine but that seems much too low.

The specs say 120VAC output which means to me at least 115VAC. I checked it with no load as well and it was the same.

I should have purchased the APSRM remote panel (battery charge indicator and mode switch.) I need to keep going under the bed to change the mode from charge only to invert. I will try to get one soon.

I must admit between the remote panel for the Xantrex C60 and the Tripp Lite inverter there will be way too much light coming from these indicators. I am going to have to find a way to diminish their illumination during the night time.

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As you can see I wired up the 220VAC from the commercial power (electric company) but I don't use anything in the house that runs on 220VAC so the line ends at the breaker. I didn't wire it back into the load center.

I had to add a second conduit as I simply had too many cables. The commercial power feed was large romex cable

The leftmost circuit breakers switch commercial power and the rightmost switch the inverter. I wired up the inverter AC-IN from the output of the commercial power breaker so that when the house is running from commercial power the inverter/charger also charges the battery bank.

2015-03-08

I decided to switch to off-grid power (inverter) first thing this morning since it was so sunny. Right now the array is providing about 35A. I happened to look at the "kill a watt" meter which is still plugged into the Cubical Monolith. I see it displaying 117VAC. I didn't understand that at first but I realized my meter may be inaccurate. I know it's a true RMS meter so that can't explain it.

This makes me a lot happier. I just wish my APC "Back-UPS" CS500 UPS (I have 2 of them on 4 LED monitors) functioned on inverter power but they all failed to accept that as usable.

My (2) DC Power supply/chargers (one on the 19" rack and one in the Cubical Monolith) are functioning normally from the main house inverter power.

I suspected this would be the case since they were designed to run off poor quality power (RV generators.)

I am still very happy to know it actually works.

This means the second set of batteries in the rack and the 55AH battery backup in the Cubical Monolith are being maintained directly from the main house inverter.

This is not the most efficient method (battery to inverter to charger to battery to inverter) but it allows me to use these designs with both commercial power and full-time inverter power.

See the block diagram at the top of the page to see what I am discussing.

I checked around noon today and the panels were producing 58A so I am very pleased about that as well. That's simply great!

I checked around 1400 and I was seeing up to 70A output which is just about the maximum that the C60 can handle.

2015-03-09

I ran the house all night off the batteries but they aren't going to be sufficient. By 0630 the voltage was 11.9V at which point I transferred back to commercial power.

I used the microwave several times yesterday which may have been the issue but I am going to try another set of (8) 100AH batteries I have in reserve.

I was running everything from 6-100AH batteries (almost 10-years old) which evidently are not capable.

2015-03-11

Part of the drain was the second home made battery backup system it was running about once an hour to recharge the batteries in the equipment rack (see above.) I have disconnected all of that and I have about 12.1VDC remaining by dawn every day.

That really isn't going to work out either but it's a start.

Living off the grid you simply must have a generator and a way to charge your batteries if there is no sun during the day.

2015-03-14

The way my load center is wired each circuit has it's own "hot" and neutral on a breaker running out in what electricians call "home run" configuration. Since I disconnected one phase "red" leg I had to install a jumper between L1 and L2 on the load center backplane. I was reading today how this causes an issue that I had not considered.

If you read this whitepaper you may be surprised about this. I know I was. The original link is here but I have it archived locally in case it disappears.

Here is an excerpt from the above whitepaper. Please pay close attention to this, I wasn't even aware of the issue at first.

The Neutral wiring in a Multi-wire Branch Circuit may get overloaded when a single 120 VAC inverter is directly connected to both the Hot Legs L1 and L2 on the 120 / 240 VAC Service Entrance Panel / Load Center / Distribution Panel as in shown in Fig. 3. Please note that both the L1 and L2 Hot input terminals of the Main Breaker in the Service Entrance Panel / Load Center / Distribution Panel have been bonded (shorted) to energize both the Hot L1 and L2 legs together in parallel with the Hot output wire of the inverter. In this case, the two 120 VAC Hot Legs L1 and L2 are being delivered voltage from a single 120 VAC inverter and this voltage is in phase on both the Hot Legs L1 and L2 of the panel. Fig 3 shows two 15 A Branch Circuits feeding two 15 A receptacles that have been wired as Multi-wire Branch Circuits. Each Branch Circuit is delivering 15 A and the voltages / currents in the two branches are in phase. Hence, the return current in the common Neutral from the two Branch Circuits will add to 30 A and not subtract to 0 A. Thus, the 15 A rated Neutral conductor will be forced to carry 30 A which is double its rated Ampere capacity and hence, will get overheated resulting in a safety and fire hazard (see Fig 3).

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