Just a quick question - if one wanted to add extra solar panels to a
shed roof which is about 30 metres away from the main array of panels,
how does one connect them up to the existing system? I'm thinking if
left as DC current then the voltage drop would be significant over
30m, so does this mean another inverter to convert to AC, and if so,
how would you connect that to the existing AC supply?
Thanks for any answers...
**DC or AC is irrelevant. It is the Voltage that matters. Low Voltages
means high currents and thus, thick (expensive) conductors are required.
High Voltage means lower currents and thinner conductors (but more
(inexpensive) insulation is required.
There are several methods of connecting PV panels.
Series: This is the most common method and Voltages of around 300 Volts
DC are common in such arrangements.
Parallel: Panels are usually rated at 12 Volts or 24 Volts, so the total
Voltage will be either 12 Volts or 24 Volts depending on the panels
used. (In reality, the Voltages will be somewhat higher under no-load
conditions.
Series/parallel: Voltages can be anything convenient with such an
arrangement.
There are advantages and disadvantages to all systems. A series
arrangement is usually the cheapest and is, therefore, the most common
one employed by installers. It is also the dumbest system for several
reasons:
* Lethal Voltages are present on the system during daylight hours.
* If just one panel is obscured by shading, the whole system shuts down.
Personally, I prefer a straight 24 Volt system, as it uses reasonable
sized conductors, is relatively immune to partial shade and is safe to
work on.
Check with Solar installers (who REALLY know their stuff) before you
begin. 30 Metres of heavy duty cable is expensive, but not ridiculously so.