[RE-wrenches] bad battery = system overvoltage = dead inverter

[Dan Fink]

This has been happening all too frequently here. We live in a big area
of off grid homes, dozens of systems.
Lost a customers Trace 2624 this morning; One L-16 in older 24v bank
opened internally. PV array/MPPT control zorched inverter as soon as
the sun came up. First indication of problems last nite when customer
hit microwave to warm up dinner and inverter went crazy. This morning
the bad battery showed 3.2v (yes, I would expect 2 or 4 also) the rest
the usual 6+v. Turned on PV array, bad battery immediately up to 11v
(yes, 6v L16).

Somebody needs to build a "battery condom" with big stacked diodes on
a big heat sink or some such solution. A voltage brick wall for system
charging inputs. MPPT PV controllers do NOT protect a inverter from
input overvoltage if all or part of the battery bank disappears! And
last year we saw a nice battery box fire and zorched inverters due to
similar -- dual 48v L16 strings, one cell failed and opened, other
string dumped everything into the bad one, smoke and flames. Parallel
fusing would have stopped that......but not stopped the loss of dual
stacked XW inverters from PV overvoltage.

Or am I missing something here?

Dan Fink,
Executive Director;
Otherpower
Buckville Energy Consulting
Buckville Publications LLC
NABCEP / IREC accredited Continuing Education Providers
970.672.4342