Difficulties Upgrading PV
Systems
- New batteries
cannot be added
to an old battery array to upgrade capacity. Mixing old batteries and new
ones reduces the new batteries to the performance of the old batteries.
...that is IF they are identically rated batteries. There are
considerably deeper
problems if you mix battery capacity.
- The solar
charge controller may is not large enough to accept more or larger panels.
- Most people start with small
solar panels. Many smaller, older PV panels can not accept the higher
voltages or current. They may have different voltage characteristics
than the panels available today.
- Older inverters were usually
designed for smaller battery storage systems within boats and RV's and were
adapted to off-grid . Their battery charging may not be up to the task
of adequately handle today's larger battery banks within off grid systems.
In Summary
In many cases mixing smaller, older PV panels with new ones and old batteries
with new may be inefficient.
Your alternatives may be to
sell the old equipment, dispose of it or relegate it to a sub set within your
electrical requirements. Just because your needs have grown doesn't
mean your older components which are still serviceable can't be usefully
re-deployed. If you just need more capacity consider reusing the what
you have for a sub system such as water pressure and outdoor lighting or maybe
the old system can be used to power the Bunkie.
Adding to Old Batteries
If you're in an area where with other off grid systems you may be able to
purchase batteries, old batteries of similar age and exactly the same make and
model to expand your system. If you purchased the system yourself, the
vendor who sold you the batteries may have contacts for you. Place an add or
call the store and see what turns up!
Adding more PV panels
PV panels of similar electrical characteristics can be added added
together in a parallel wiring configuration to provide more power. If the older
panels cannot handle more current (amps) they can be joined in a parallel
configuration at the combiner box which then leads the power to the solar charge
controller. If you're not sure of the older panels' charge characteristics, a diode can be imposed to protect the output from other panels from
being consumed by the older panels.
Older panels with differing
voltage can be combined if joined in a series wiring configuration as long as
the voltage and current rating of the panels isn't exceeded. Not many
solar charge controllers can handle and convert higher voltages without power
loss, however, the many MPPTwill.
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