Month: July 2017

Our new off-grid solar goes in

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One of the things we liked about our farm when we bought it was that it was truly off-grid. That means managing our own power, water and sewage. Truly living the eco dream!

What we weren’t so excited about was the terrible state of the solar generation system. It hadn’t been serviced in the last decade, meaning the lead-acid batteries had been allowed to go dry, the generator was failing, and the lights dimmed every time the water pump when on.

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The old batteries, hugely heavy (50kg+), which had been allowed to go dry

So a brand new PV system was required. Our immediate challenge was finding someone who could sell and install a solar solution.

Our farm is located in a rural setting surrounded by rainforest and fields. But it’s also just 10 minutes away from the nearest town, making it semi-urban.

The net effect is that very few of the local PV systems are off-grid, and few of the local installers had experience with off-grid setups. We wanted someone nearby to do the work, so we could get good post-installation support.

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Installing the new panels on the roof

It’s worth  highlighting at this point that there are power lines that run across a corner of our property. Connecting to the grid, however, would cost $20-30k, and then we’d have to pay electricity bills.

We ended up getting one good quote for a new system, for a total cost of $30k. So the same up-front cost, but with a lifetime of free power. That was an easy decision.

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The heart of the new system, a Sunny Island controller, and a Sunny Boy inverter

The key components of the system are as follows:

  • SMA 6Kw Sunny Island, which is a beautiful bit of kit that charges the battery and manages the local grid
  • 5Kw of solar panels, on the north-facing roof of the house
  • Sunny Boy inverter for the panels
  • 17Kwh of battery storage, utilising lead-carbon gel batteries
  • 7Kw Honda petrol generator, with auto-start
  • web-based interface for monitoring the system

It took the team three days to strip out the old system and to install the new one. Right from the beginning it’s been working well, and getting enough sun even in mid-winter (where the sun hits the panels at 11am, until 3pm when the sun dips behind the mountain).

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The new lead-carbon batteries, quite a difference from the old monster batteries!

A few notes:

  • The general rule of thumb for off-grid is to have 3 days of usage in the batteries, to cover off the occasional rainy week.
  • The generator has been configured to kick in if the batteries reach 30% of capacity, and to then take them back up to 70%.
  • We didn’t use lithium-ion batteries (like the Tesla Powerwall) because they’re not yet designed for off-grid, and the price is still too high.
  • The system operates as a “local grid”, allowing me to re-install the old PV panels on the new shed, connect them to a small inverter, and then just to wire that into the grid. T’he Sunny Island then manages the load across the system as a whole, which is a very elegant solution.

It’s early days for our solar setup, and we’ll report back as the months unfold.

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The new panels in place, three rows for a total of 5Kw

 

 

Home-made wax fire lighters

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When browsing Pinterest I came across instructions on how to create home-made wax fire lighters.

With a fair bit of unprocessed wax on hand at the end of the beekeeping season, I was very interested. Particularly for the wood fire down at the farm, in these colder winter months.

I started by melting down a big lump of wax, which you can see contains a fair bit of gunk.

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The messy pile of left-over wax at the end of the beekeeping season

A good friend of ours provides us with big bags of free wood shavings, to use in the chicken coop. I used these to fill up a number of paper muffin cups.

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Muffin cups filled with wood shavings

The hot wax then went into the paper cups, the result being (once cooled), a set of unusual-looking fire lighters.

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One of the final products — and it works!

Now I won’t claim that these are as quick and easy as the fire lighting blocks that you can buy. They take a bit of convincing to light, but once they’re going they work well.

They’re particularly effective at restarting the fire each morning, as the coals are still warm from the night before. This primes the wax to light more easily.

If nothing else, these are a great way to make use of available materials that we get for free, namely: wax and wood shavings. Happy days.