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Off grid with solar and batteriesTime to go off grid? Enough of paying high prices for ridiculous connection fees to your energy retailer. Enough of getting 6c for feeding power back to the grid. It’s time to go off grid with solar and batteries. I feel your pain. But allow me to be the voice of reason, assuming your motivation is either economic or environmental. Let me show you what this may involve. Now, let’s assume best-case scenario: you don’t use much power.


Off Grid Grandma style!

  • You are paying $100 for a connection fee per quarter.
  • You only use 10kWh a day of power. 5kW at day and 5kW at night.
  • Your power bill is about $300 a quarter.

What solar capacity would you need?

  • Enough storage to last an absolute minimum of 2 rainy winter days.
  • Enough panels to produce enough power for three days (the two rainy days plus the sunny day before).

What size system would you need?

  • 25kWh of usable battery capacity (1 Night beforehand and two rainy days & nights).
  • 30kWh of solar production on an average winter’s day.

What will that cost?

  • If you get batteries installed for $1500 per kW, you are doing well: $30 000.
  • You’ll want 9kW of Tier 1 panels (installed) to produce 30kWh a day on a winters day in Brisbane: $7 000.
  •  Yo may go for an economical stand-alone or “off grid” inverter that will handle 9kw of panels. Installed: $5000.

So we are starting to look at a price over $42 000.  Considering your bill was $300 a quarter, or $1200 a year. Assume inflation in electricity matches degradation of your panels and your battery capacity. It will take you 35 years to pay the system off. The batteries will be warranted for ten years at best. Hmm indeed.

The $42 000 problem

The problem with the above off-grid equation is the excess storage you need for a rainy day. The problem only exacerbated if you exceed Grandma’s 10kW a day usage. But … If you could only eliminate the $30000 in battery storage, we would be well on our way. The most economical and environmentally sustainable way to do this currently, for better or worse, is to have an alternate source of supply for rainy days. Yep, pay your connection fee of $100 per quarter to the grid.

The solution – hybrid ready

While its not feasible to go off grid, Hybrid solar is here. Hybrid combines a standard grid connected solar system with batteries storage technology. You will still have to pay your connection fee, but you won’t have to give away power for 8 Cents. In most situations, batteries are still too expensive to make it viable, but give it a few years, and we will be there. Until then, get panels up on your roof making hay while the sun shines, and have your inverter “battery ready” for the imminent battery revolution.

The Exception

If you just want to go off grid because you have a spare $40 -50k, and you like the idea of being a pioneer – then please ignore this blog and give me a call!

If you know someone who has gone off grid, how did they go? Leave a comment
Mark Cavanagh

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