30 Volts. PV Examples
Most folks will probably buy LCBs for low-loss, long-distance PV power transmission. Wiring panels in series wastes less power to resistance wiring. See "Long Distance Power Transmission" by Paul Cunningham in HP #28. How many panels in series? This is limited by the open circuit voltage of the string. Multiply the open circuit voltage (Voc) printed on the back of each panel by the number of panels in series. This must not exceed the voltage rating of the LCB. LCB40s come in 50 Volt, 100 Volt, and 250 Volt models. A number of series strings may be wired in parallel as long as the final output from the LCB does not exceed 80 Amperes. Set the voltage threshold on the LCB to your best estimate of the maximum power voltage (Vpmax). For PVs, multiply Vpmax (printed on the back of each panel) times the number of panels in series to get Vpmax for the series string. If it's hot out, subtract 10% to 20%. See "Home Power Measures PV Performance" for Vpmax at 50°C for various panels, HP #24, page 26. A properly adjusted LCB will help reduce line losses, and will cajole more power from your PVs. However, you probably won't see the 50% increase we see out of our wind generator. Our wind generator was originally operating far from its maximum power point, while your solar panels probably aren't.
The LCB40 can be outfitted with a battery charge controller, making it the LCB40CC. The charge controller has a toggle switch for 12 or 24 Volt mode to match the nominal voltage of your battery pack. You can order a lead acid regulator (13 Volts - 15 Volts in 12 Volt mode, 26 Volts - 30 Volts, 24 Volt mode) or an alkaline regulator (extended to 18 Volts in 12 Volt mode, 36 Volts in 24 mode). You can also choose three different regulator types. The ECM1 ($99) is a switching series regulator, which gives pulsed charges to the battery. The OVL regulator ($50) is a constant voltage regulator. Both the ECM1 and the OVL are for PVs only. For wind or hydro turbines, a charge diversion (shunt) regulator option will soon be available for around $100.
Packaging, Documentation, and Installation
The LCB40 arrived well packaged in nasty styrofoam peanuts. The documentation for the LCB40 is short but adequate. It tells you what the LCB40 does and what you need to know to install and operate the unit within its operating range. Installation is very straight-forward. The LCB40 is 10" x 11" x 3" and mounts on a wall with two screws. There are four wires to hook up, positive and negative to the battery, and positive and negative from the charging source. We commend Sun Selector for providing large electrical terminals. These terminals, however, are exposed from the front, and present an electrical shock danger. To conform to the NEC®, the LCB would need to be encased in an additional metal enclosure.
We now have a pronounced increase power. During the windy winter months the Survivor put out a maximum 38.8 Amperes at 14.8 Volts = 574 Watts. In two months since we've installed the LCB40, we've seen a maximum current of 67.6 Amperes at 13.8 Volts (919.4 Watts). On a windy day, we regularly see currents over 55 Amperes. In our situation, the LCB40 delivers 60 to 90% more current out than is put into it, as shown below in the graph. Input and output currents were measured simultaneously with
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Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.