Making our own electricity

The mounting frames are the Schüco MSE 210 ground mounting system.  I have got three sets of this; each set will take 8 of my panels, which makes the decision to have 17 panels look wildly eccentric – but there is a reason.

Each frame is held up by a single row of 3 vertical posts.  The picture below gives a good idea how this works.

One mounting frame

One mounting frame - seen from behind

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The instructions say that the posts should be rammed into the ground, using a hydraulic rammer.  Well our local first-class erector of fencing, Russel Norman, has suitable equipment – I happen to know because he’s had it here putting up fences.  But when we tried it we hit a problem; in fact we hit bedrock before the posts had gone far enough in.  Sandstone, frequently found underneath the local clay, and near the top of hill it will be quite shallowly buried, as Russell, who has learned all this through years of fence erection, pointed out.  So he had to come back again, with plan B – boring machinery.  A giant powered auger.  The posts then went in with spirit level accuracy and dead in line.

The next picture shows how the panes are daisy-chained together electrically.  Each one is plugged into the next in a single “string”.  So the 30 – 36 volts that each panel produces add together to give a total system voltage of 500 – 600 volts.

Daisy-chaining the panels' electrical connections

Daisy-chaining the panels' electrical connections

The final output comes from the first and last panels in the chain and it disappears underground down a conduit for which Russell Norman dug the trench.

Taking the power out

Taking the power out

The underground cable is 3-core 10mm SWA (steel wire armoured) copper cable.  The supplier had given us something which I didn’t think was suitable at all – not armoured and with a steel conductor and quite flimsy.  Probably intended for a roof-mounted system but not in my opinion safe for undergrounding – a spade or plough would have gone straight through it.  Fortunately we had the SWA cable surplus from an earlier project.

The DC is (will be) converted to AC by the Fronius solar inverter. The back-plate for the inverter can be seen at the right of the photo below.

PV and battery control equipment

PV and battery control equipment

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