It’s a bit early to do a case study on solar power for the Otaki Motel, because quite frankly, we haven’t received enough data yet to assess how much of an impact our 1.5 kWh solar power system has had on out energy use across all weather patterns and seasons. What we have had is our first electricity bill come in.
The motel has multiple ICPs and in order to gain maximum value from the system, we set up the panels to power the ICP that had the most amount of daytime energy consumption. So for the purpose of reviewing this bill against the corresponding month from last year, and from the previous month from this year, I’ll be looking at that ICP in isolation.
How This Month’s Bill (With Solar) Compared to Last Month’s Bill (Without Solar)
The comparison between the two months (this last month of October 2017 and the prior month of September 2017) show a marked drop in energy consumption and cost at the ICP, far in excess of what I was expecting.
Last month’s bill ran from 11th September to 10th October. Last month showed 612 kWh consumed during Day hours (from 7am to 11pm) and 334 kWh consumed during Night hours (11pm to 7am) on our Day/Night ICP. The total cost of this consumption, including the daily charge, EA Levy and GST, came to $225.76 for that month.
This month’s bill ran from 10th October to 9th November. This month showed just 316 kWh consumed during Day hours and 238 kWh consumed during Night hours on our ICP. The total cost of this consumption, including the daily charge, EA Levy and GST, came to just $132.85 for that month.
That’s a drop of $92.81 or a reduction of 41% for the period. My original forecasts contemplated a drop of around $28.52 per month.
How This Month’s Bill (With Solar) Compared to the Corresponding Bill From Last Year (Without Solar)
But comparing two different months isn’t exactly fair, because it doesn’t account for the change in energy use as we move away from winter, right? Which is why I was surprised to learn that the reduction in cost and energy consumed from the October bill from last year were even more pronounced than the results comparison above.
As per above, this month’s bill showed 316 kWh consumed during Day hours and 238 kWh consumed during Night hours, with a total cost of $132.85 for the month.
Last October, however, we consumed a total of 948 kWh across both Day and Night, with a monthly cost for our ICP of – get this – $284.89 for the corresponding month. (That’s inclusive of GST, and a prompt payment discount of 20% with the energy retailer we were with that year, but with no mention of the EA Levy.)
Not a bad result over one year! That’s a drop of $152.04 in monthly power expenses or alternatively a 53% reduction in cost over 12 months. To keep it in energy consumption terms, it’s also a reduction in 394 kWh of energy consumed from the grid, being a 42% drop in energy consumed.
The only problem with the above analysis is that we have since a) switched energy retailers and b)switched from an Anytime meter to a Day/NIght ICP. The reason this was done was to save money – and indeed it did – but the changes would not necessarily have had any impact on the gross amount of power consumed.
Conclusion
I am still scratching my head trying to make sense of the mysterious drop in power consumption. There are plenty of possible reasons for it, none entirely satisfactory, but I am pleased with the result. I will have to wait as more bills come in to see if I can attempt to fathom possible causes for such a significant reduction in our chargeable energy consumption. For the time being, however, I’m happy to accept that the above comparisons may be a blip on the graph and future energy consumption reductions may not be so fascinatingly significant.
