Phase Shift To An Alternate State

The system

This connected inverter is not yet grounded

Doesn't work. Looking for a fuse

Found two fuses - and they are blown

Replaced the fuses
All you really need are a battery and an inverter. Just keep the battery charged and you are in business. All the other components (PV module, combiner, controller) are just to keep the battery bank charged. You could replace all of them with a stationary bicicle and a transformer.

Oh yes, the ground; you need a ground. It is so easy to forget that one essential component. I went through hell installing the grounding system - and then I forgot to use it. I set up the battery bank, making very sure I got all those cables just right, especially the cables of equal length to the inverter. I connected those cables, first one, then the other - which threw a spark, but only once. I tightened them down.

The batteries had come fully charged from Autozone. I was excited; I wanted to see it work - I plugged a lamp into the inverter and turned it on ... nothing happened. I flicked the switch a few times and looked things over, trying to see if I had missed something though I knew I hadn't. This was quietly disheartening.

I sent an email to Exeltech and they responded that I had done everything right, a spark is normal and it probably blew a fuse. What! Is it going to zap a fuse every time I connect the cables? That doesn't seem quite right. Then something came from the back of my mind - maybe the inverter should be grounded first. If that were so then it could indeed have blown a fuse. I opened the inverter and I found two fuses. My volt-ohm meter showed that they were dead so I took them to Radio Shack and got new ones. I ran a green wire from the inverter's 'GRD' to a clamp on the main ground wire.

Again I turned the inverter on --- it worked! The LED came on and my lamp lit. Wow! So simple.

This time it is grounded

This time the LED works

It definitely works
On March 1 I moved the power strip and the various charging cubes from the van to the new inverter and turned it on. This began my first real use of the new system even though nothing was connected on the charging side. The panels were not on the roof yet because I was waiting for more grounding lugs - and I was in no real hurry because the general wiring inside the little house was not yet done.

That single charge on the battery bank kept all of my rechargeables going for two weeks including my notebook computer, cell phone, cordless tools, three lamps, and etc.. The inverter shut down when the battery voltage got too low. At that point the readout on the charge controller showed the battery bank at 36.7 volts DC. Down from 51.2 volts, that is only a 28% depletion. Deep cycle batteries in general are supposed to handle 60 or 70% depletion and the Optima even better, so I'm not sure why the inverter cut off so soon.

On March 17th at 2:30 the lugs arrived. By 7:00 PM the PV modules were installed. First thing the next morning, the MC-3 cables were brought through the wall and connected to the breakers inside the combiner box. On March 18th at 8:09 AM the breakers were switched on and the solar system became active. At 4:02 PM the batteries were fully charged and the inverter was switched on. Been that way ever since.

One odd note: the small bolts that held this lid on were unusual, a square hole or maybe a star, I don't recall. All other screws are phillips. I had to go buy a bit to fit them. On my next trip to Home Depot I found 4 matching brass bolts with a standard slotted head to replace them. I guess somebody at Exeltech decided to make it difficult for novices to penetrate the guts of the machine, not realizing that we might just need to replace a fuse.

Tapping 120 volts AC

One additional note: you would not want this system installed where you sleep or otherwise need perfect silence. Not only does the charge controller have a slight ring to it, the inverter proceeds with a heavy buzz whenever a heavy load puts it to work such as when the microwave is running or the refrigerator kicks on. On the other hand it can be useful. Like becoming familiar with the sighs and quiet grumbles of your dog you begin to know by the sounds what is going on in and around the place, electrically.

Another significant point I have often come across: when the inverter is on it consumes power all by itself. That is why it was designed to shut down entirely when there is no demand. If you have anything with a 'keep-alive' feature plugged in such as a TV or a clock that is constantly drawing power, they will tend to keep the inverter running and drawing unnecessary power. Switch the TV off with a wall switch or power strip. Buy special devices designed to conserve power and use battery powered equipment. Only charge your rechargeables in the daytime when the inverter is probably already on for other purposes.

1. General info: EXELTECH true sine wave inverter
2. Specifications: XP Series Inverters (1100 Watt, 48Vdc)

Copyright © 2008, Van Blakeman