Displays vital battery system data to help users provide better battery care, increase conservation awareness and aid system maintenance.

Bogart Engineering • (831) 338-0616

19020 Two Bar Rd. Boulder Creek, CA 95006 USA

Q with more capability

Data logging, five customizable buttons and displays, audible/visual alarms, three "amps" input channels, relay control, computer interface

Is data logging really useful in a system monitor?

When an offgrid system is first installed everything usually starts out working OK. But after awhile it may not work quite like it used to. Bad battery cell? Solar panel developed a problem? You can download the last few weeks of logged data to your computer and compare it to data recorded earlier when everything was working OK. Or email the file to some other "expert" who can analyze it without even coming to your home.

On our website download the document: " How to graph and analyze renewable energy system performance using the PentaMetric logged data".

The PentaMetric system with computer interface only is about $320. LCD Display unit (above) additional $199. See website for more information.

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Changing Codes

& Grid Connection by John Wiles

The final connection between a utility-interactive photovoltaic (PV) system and the electrical utility grid is an area of importance to PV system designers and installers. Due to the varying sizes of PV systems and configurations of existing service-entrance equipment, these connections vary significantly among PV systems. Differences in Section 690.64 of the 2005 and 2008 editions of the National Electrical Code (NEC) make these variations even more complex.

Load-Side Connections

Section 690.64(B) establishes the load side (of the main service disconnect) connection requirements for the utility-interactive inverter output. The key to understanding this section is to carefully read 690.64(B)(2) and note that the ratings of overcurrent devices supplying a bus bar or conductor must be added so that the sum of these ratings does not exceed the rating of the bus bar or conductor. The ratings of overcurrent devices supplying loads are not counted. Also note that the overcurrent device (normally a circuit breaker) rating is used in this calculation—not the current flowing through the circuit. Overcurrent devices to be counted are the main breaker and all breakers backfed from utility-interactive PV inverters. This equation expresses this ratings requirement:

PV + Main < Bus or Conductor

In the 2005 NEC, this requirement applies only to commercial (nonresidential) PV installations. Here's an example: Say the site has a 400 A main service panel with a 400 A main breaker. In this case, no PV can be added to the panel. In many commercial installations, this limitation forces the installer to use a supply-side connection (see "Supply-Side Connections" section).

For residential installations, a 120% allowance is included. This exception makes installations somewhat easier:

In this residential example, a 200 A mains panel with a 200 A main breaker could have up to 40 A of backfed PV breakers connected.

Section 690.64 was rewritten in the 2008 NEC to apply the 120% allowance to commercial installations—but only

Requirements for Commercial Grid-Tied PV Systems

Getting Started With Solar

Getting Started With Solar

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.

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