The type of inverter you pick is another prime consideration. Inverters convert DC, or direct current (e.g., the energy source we typically use in batteries), to AC, or alternating current, which powers everything in our homes, from lights and appliances to electronics.
Andre Oelmann, a commercial electrician in Crystal Beach, Ont., who built an off-grid home a few years back, is a big proponent of using microinverters—with one unit assigned to each solar cell—versus string inverters, which tie one inverter to a block of solar cells (e.g., a block of eight or 16 cells, depending on the string inverter).
Oelmann chose to go with microinverters for his system despite their significantly higher cost (average of $1.25 per watt) compared to string inverters ($0.75 per watt). As he explains, “For me it has to do with such problems as shadows. If you have a tree that’s blocking the sun for one panel in a string of eight or 16 (panels), the rest of the string will shut down to the lowest amount (of energy being produced).”
Conversely, he says, if your system is composed of microinverters, the shadowing effect only affects the performance of the individual panels being shadowed while the remaining panels continue to operate at full capacity.
But getting back to cost: a string inverter tied to anywhere from eight to 16 panels might cost $3,000, and the equivalent microinverters could cost $5,000 to $6,000. However—and this potentially makes things confusing for buyers—Oelmann says there are smart solar panel optimizers that work in tandem with string inverters and essentially do the job of a microinverter. But then, not unlike microinverters, you need optimizers for every panel… so at the end of the day, cost-wise, the overall cost could be the same, and the solution you go with could ultimately come down to what your solar provider recommends.
Mind you, Oelmann isn’t your average solar PV consumer. In addition to the 20.1-kW system on his roof, he has four Tesla Powerwalls, each with a storage capacity of 13.5 kW, whereas the average home owner might be happy with just one. He also lives in a highly energy-efficient home that’s close to qualifying as a Passive House (an international building standard for energy-efficient architecture). Oelmann strongly feels that the government should mandate Passive House as a standard, “if it’s really serious about reducing Canada’s carbon footprint and fighting climate change.”
Should you get backup batteries?
Yes, if you can afford it. In terms of backup battery solutions, not surprisingly, Tesla Powerwalls don’t come cheap. To have a single Powerwall installed in our home, I was given a ballpark price of $15,000 to $20,000—an amount that could easily double the cost of a solar system.
But, thankfully, there are lower-cost solutions out there. For instance, earlier this year, EcoFlow offered 3.6-kW batteries, enough to meet the daily energy needs of most homes, for $3,999, as well as a 7.2-kW version for $6,999. And you can continue to add batteries—the system is scalable up to 21.6 kW. However, regardless of the size of your system, you will need to get a transfer switch installed (approximately $465) to connect the batteries to your electrical panel, allowing you to choose what to power during an outage. (Note that solar system pricing is a moving target.)
Mark Douglas Wessel
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