Installation manual

that creates a voltage between items will create a large current in the earth bonding that will

blow a fuse and disable the system. Also connect this protective wiring to an earth

electrode so you are protected from electric shocks when you are also touching earth or

earthed objects.

This is very basic electrical safety. It is also the front line of protecting sensitive equipment

against lightning induced surges of voltage. Equipment grounding will help protect the

electrical system and appliances from lightning surges although the level of protection is less

than commonly believed. Some inverters and MPPT controllers may include lightning surge

protection.

6.2.3. System earthing

Earthing of the DC negative of your renewable energy generation system (known as

"system earthing") may be required for personal safety and protection of the system from

electrical faults. Not all 12/24/48 V DC systems are earthed and the rules vary from country

to country. Systems operating over 120V should almost always have a system earth

connection. Equipment should always be earthed as above, regardless.

Without system earthing you will need to use double-pole fuses and breakers. An "earthed

system" only needs protection in the "live" side (single pole fuses, etc).

6.2.4. AC side system earthing

This manual does not fully cover AC system earthing requirements, as this must be done by

a registered electrician. A battery based inverter provides an AC supply where neither side

of the circuit is earthed, and so this "system earth" connection must usually be made as part

of the installation if desired or required. The AC neutral should be bonded to earth in one

place only. The main distribution board is a good choice.

An electrician without good off-grid experience may be confused by the need to earth the AC

neutral and may need to be shown the directions in the inverter manual

regarding the earthing arrangements of the system. In some countries the

electricity company are responsible for earthing the neutral of the supply,

and hence some electricians have never done this work. In off grid

systems where there is no power company they have to do all the wiring

required to comply with regulatory requirements.

6.2.5. Earthing of the PowerSpout turbine bulkhead

We recommend the installation of an earth electrode at the

PowerSpout to minimize the possibility of there being an

electrical hazard and to minimize any electrical noise generated.

The main reason to earth the PowerSpout bulkhead is to stop

users touching metalwork which may have become live through

an electrical fault. This metal bulkhead is connected to the same

ground the user is standing on so the user is protected from

shocks. However this protection depends critically on the

impedance of the earth connection being low enough to make it

safe.

There is little global experience with small DC hydro turbines, however, DC solar PV

systems are very similar and hence we advise you to follow the same general rules as for

solar PV systems. The main difference is that hydro turbines are not installed on your home

and hence any fire risk is much lower.