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Old 01-03-11, 05:59 PM   #6
Lex Parsimoniae
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Join Date: Feb 2009
Location: Woburn, MA
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One of the main goals of this back-up system is to provide 2 to 3 hours of power for four sump pumps.
Since the 4 pumps (each using about 300 watts) would start up and run at random times,
with about 30 seconds to 1 minute of run time, per 3 to 5 minutes of Off time.

It's very likely that normal flooding will cause the use of less power,
than would be used by running 400 watts continuously.

My guesstimate is 0.3 to 1.0 kWh being used during each hour of flooding,
depending on the height of the flood-water table.
(Unless we get another 100 year flood, ahead of schedule).

The main load is these three new pumps and one old Ace Hardware 1/3 HP pump.

The Gray box is a SumpJet water powered sump pump.
(In case everything else fails)..

The run time of the battery bank during a flood will depend on SOC and if the sun comes out.
Most of our flooding occurs 1 to 3 days after heavy rain has stopped.
So, there is a possibility that battery life could be greatly extended by the PV.
Which, at 300 to 500 watts could drive the pumps while simultaneously recharging the bank.

The reason for the 2 to 3 hours of power as my goal is simple.
In 90% of power failures during flooding, the power is quickly restored.
In any kind of weather, 90% of the time, NStar has restored power in less than 3 hours.

Two or three hours of a dead grid, should be plenty of time to roll the
5KW gas generator out of the garage and get it running.
(Which is something that I would like to avoid if possible).
But it might be unavoidable if the flooding is heavy and the battery bank falling low too fast..

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