What We Talk About When We Talk About Solar

 In Design, Energy Systems, Solar, Verge Permaculture, Why Permaculture?
solar-array-denmark

A solar array at the Folke Centre For Renewable Energy in Denmark.

Through the Adaptive Habitat program, we regularly work with clients keen on investing in tangible assets for an uncertain future. Together, we design insurance safeguards for essentials like food, water, power, shelter, and heat. Solar is one of those assets we help people design and project manage on a regular basis. Surprisingly, it’s also something many misunderstand, especially when these systems are synonymous with notions of resilience and self-reliance.

Solar’s Common Misconception

Many solar arrays in the market today are grid-dependent. What that means is that surplus generated power feeds back into the wires when household demand is low and is “banked” for future drawdown. But because the grid considers these solar systems nano-generators, they are shut down during power outages. This is so that electricians who repair utility systems don’t get electrocuted by live systems powered by decentralized solar arrays.

This fact often comes as a shock to our clients (no pun intended!) who think of solar arrays as their primary backup power sources during outages.

A “Grid-Hybrid” Solar System

If you’re in the market for a solar array that can provide backup power in the event of an outage, you’ll need to make this clear to your solar service provider. The system you want if you’re planning on staying on the grid (versus going off-grid entirely) is called a “grid-hybrid” system. These systems have all the advantage of an on-grid system that can handle energy-intensive activities but also have the ability to function as an island when the grid goes down. The most significant change is that the inverter has a rapid shutdown functionality that can also function without external dependencies.

These systems are becoming more and more viable with the release of new battery technologies like the Tesla Power Wall. The last system we designed and managed that had the ability to work in both a grid-up or down scenario comprise the following pieces of equipment:

  • 12 kW solar array
  • 2 x 15kWhr Tesla Power Walls
  • SolarEdge Inverter
  • 10 kW Kohler generator
  • 2 x 1,000 gallon propane tanks

The SolarEdge inverter manages all the system components, including when to turn on and off the generator. The solar array produces the power, supplying it either to the house or charging the battery walls. Excess power is sent off to the grid once battery and household needs are met.

kohler-generator

In the event of a power outage, the array will provide the majority of the power needed to run household needs. If there’s an extended blackout or a prolonged period of low solar hours, the generator will kick in to meet household demand and charge the batteries. Once the system is set up, the propane tanks should only need to be filled up every 10-15 years. With this type of reliability, I think this is more inline with what people think when they think about a self-sufficient solar energy system.

Are you ready to design, create, and maintain a resilient property that you can depend on during uncertain times? Check out our Adaptive Habitat Program, available either in a FREE self-study package or an expert-guided and guaranteed program!

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Showing 2 comments
  • Rob Cooper

    That was great Rob. Thank you.

    I’ve been looking into this as our next step. What I’ve done here over the past year is install a second panel in our basement I’m calling our backup panel. It has new lines run to various elements of our basement power needs. A few lights, a few plugs, our sump pump, freezers and I re-routed our upstairs fridge into it.

    The next step is to add the panels on the roof, and install the rest of the guts to work the way you’ve described above.

    With the incentives provided by the province and the city now (in addition since Jan 2019), it just seems dumb not to.

    It might be good to add a small section on any stories you know of showing how much money can be made selling the power back to the grid. I’ve got a buddy in WA state that invested $15k US, had his power costs cut by 50% immediately and has gotten a $5k cheque each fall now for 3 years in a row. The system paid for itself already and his power costs have halved.

    • rob avis
      rob avis

      Rob, power is too cheap in Alberta to make any money at it. There is one power supplier that will allow you to flip your rates seasonally with them so that in winter you pay their cheap rate to import/export and in the summer you agree to pay their expensive rate to import/export. This gives you an advantage if you system is large enough as the majority of your power comes in the summer months so you can technically make money. Expense power is coming, it has too. It will either be LNG, peak gas or a wake as to how piss poor tight gas is as a resource.

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