monitoring equipment--oh say have you seen? [RE-wrenches]

[Doug Pratt]

Okay then, lemme display my ignorance...what's this multi-channel Brand meter, and
where do I find one? Sounds like just the ticket for battery-based intertie systems.

-Doug Pratt

Joel Davidson wrote:

> I use Ethan Brand's 4 channel unit (3 AC and 1 DC) on my own 2kW net metered PV
> system. With more meters than necessary I read:
> a) electric service panel for net kWh (grid and SW4048 AC1)
> b) 120VAC kWh meter on the standby loads subpanel (SW4048 AC2)
> c) C40 controller meter for DC volts, amps, watts, amp hours
> d) TM500 monitor for DC volts, amps, amp hours and % battery full
> e) SW4048 for its various readings (I leave it on AC load for production amps)
> f) Brand DC shunt for cumulative amp hours into battery bank
> g) Brand on AC1 from service panel to inverter
> h) Brand on AC1 from inverter to service panel
> i) Brand on AC2 from inverter to subpanel.
>
> I started monitoring my system daily 11/19/00 through 12/30/00. Then I switched
> to monthly to match the utility bill period starting around the 20th of the
> month. Some time between 2/20/01 and 3/20/01 the Brand meter reset itself. There
> was no utility or PV system power outage during the period so the cause for the
> reset is unknown. Lesson re-learned the umpteenth time is if you use volatile
> memory and collect long-term data, then make daily readings to catch problems
> and only lose one day of data. Since the one and only "hiccup," Ethan,s meter
> has been working fine. All measurements confirm what we already know, that PV
> performs as predicted.
>
> 1. Has anyone else has had a Brand meter hiccup? What was the cause?
>
> 2. Has anyone come up with a way to keep standby batteries on line but shut the
> SW4048 float charge off?
>
> Commentary. PV is wonderful. That said, two continuing disappointments are Trace
> line-tie PV systems with batteries not having MPPT and the SW4048 consuming 7 to
> 8 kWh per month to float charge batteries that are just standing by not being
> used. On the other hand, it is nice to have a net metered PV system that
> requires virtually no attention and batteries on line when a utility blackout
> occurs. Our neighborhood is 5 miles north of LAX in Southern California Edison
> territory. In the past month we had a 1.5 hours stage three rolling blackout and
> a 16 hour outage due to wire and transformer failure. Both times our system
> performed flawlessly with no interruption or interference to computers, modems
> and phones. This very urban SCE circuit we are on was only black for 20 minutes
> during the 1994 earthquake and has been down only a few times for short periods
> since 1984. But if recent events are a forewarning and not an anomaly, then this
> summer should be very interesting and an great time for California PV installers
> to sell PV UPS to commercial customers.
>
> Go to Tom Hoff's excellent Clean Power Estimator at
> http://www.energy.ca.gov/cleanpower/
> and play with the numbers. Your commercial customers should be pleasantly
> surprised at the economics of a PV UPS when you factor in the buydown rebate,
> 10% investment tax credits and accelerated depreciation. Any business that puts
> in a UPS without PV is throwing away money.
>
> Brightly,
> Joel Davidson

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