What does a bad month actually look like?
An average tells you nothing about a risk. This page models what you would pay under deliberately adverse market conditions - and then models the same conditions again with a battery in the house. We publish it because a wholesale product without a worst case on the page is not honestly sold.
The risk, plainly
Wholesale electricity prices are set every 30 minutes, and price spikes are not capped. Most half-hours of the year the market price is well below a standard retail rate - that is the point of being a member. But in a shortage it can spike violently for hours, or sit uncomfortably high for months. If you are on wholesale pricing, that risk is yours - so here is what it actually looks like, and what we do about it.
The three scenarios
Normal market conditions. Ordinary supply and demand. Prices move through the day but stay within a familiar band - cheap overnight, dearer at the morning and evening peaks.
Sustained high prices - $400/MWh for three months. A generation shortage: a dry hydro year, a gas outage, a cold still winter, holding wholesale prices at 40 cents a kilowatt-hour for a sustained period. This is the scenario that hurts.
A short, violent spike - $10,000/MWh for eight hours. The classic wholesale event: an eight-hour window at $10 a kilowatt-hour caused by a sudden loss of generation or transmission on a high-demand evening. Short, brutal, and not capped.
The stress test
The figures below are monthly, energy plus the $0.02/kWh service fee, including GST. Network, metering and levy charges are on top and are unchanged between scenarios.
Using 900 kWh a month - normal conditions: $150 without a battery, $102 with a Fever-1. Sustained $400/MWh: $368 without, $316 with. An 8-hour spike at $10,000/MWh: $304 without, $122 with.
Using 1,300 kWh a month - normal conditions: $217 without, $147 with. Sustained: $532 without, $456 with. Spike: $439 without, $235 with.
Using 2,000 kWh a month - normal conditions: $334 without, $260 with. Sustained: $818 without, $738 with. Spike: $675 without, $468 with.
How PowerHub manages the risk - three simple steps
Step 1 - Buy at wholesale. Members pay the half-hourly market price plus our flat service fee. Most half-hours of the year that price is low - overnight and off-peak it is often a fraction of a standard retail rate. The saving is real, and so is the exposure at the peaks. The next two steps are how we manage it.
Step 2 - Store it in a battery. A subscribed Fever-1 battery in your home charges when power is cheapest and runs the house through the expensive peaks - and through a price spike. Because it sits at your place rather than in a distant grid facility, it is also your backup power in an outage: distributed storage that keeps the lights on when the network cannot.
Step 3 - Generate with solar. Solar PV on your roof produces power at zero marginal cost, whatever the market is doing - which is exactly what helps in a sustained high-price market, when there is no cheap half-hour for a battery to charge in. Paired with the battery, it is distributed generation that fills your own storage from your own roof.
Thousands of homes doing this together form a distributed power station: storage and generation spread across the network, managing wholesale price risk household by household - with resilience, backup power where you live, as the built-in bonus.
How much does a battery actually help?
In normal conditions, every day. The battery earns its keep by moving roughly a third of your consumption out of the two daily peaks and into the overnight trough.
In a short, violent spike, enormously. This is what the battery is for. A charged Fever-1 carries a typical household through most of an eight-hour event without drawing from the grid, and it charged the night before at single-digit cents.
In a sustained high-price market, much less - and we would rather be clear-eyed about that. When prices are high all day there is no cheap half-hour to charge in, so the battery narrows the gap between peak and off-peak but it does not remove the problem. In that scenario generation helps more than storage, which is why we also sell solar: a 7.2 kW set produces power at zero marginal cost regardless of what the market is doing.
What these numbers assume
Thirty percent of your consumption falls in peak periods and seventy percent outside them - conservative for a typical household; if you already shift load overnight, your real exposure is lower than shown. The battery is a 15 kWh Fever-1 cycling once a day at 90% round-trip efficiency, using 13.5 kWh of its capacity. It discharges into your most expensive half-hours and recharges in the cheapest, and the model charges you for the round-trip losses. It does not assume you export at peak, and it does not assume perfect foresight - both would improve the numbers, and we have left them out. Network delivery, metering and the Electricity Authority levy are excluded: they are real costs and they are on your bill, but they do not change between scenarios. Neither stress scenario is a forecast. Both are chosen because they are severe enough to be uncomfortable and plausible enough to have happened before in some form.
No price is guaranteed
Wholesale prices are set every 30 minutes and spikes are not capped. Any figure shown here is an illustration using the assumptions stated on this page; it is not a forecast and not a limit on what you could be charged. Wholesale pricing suits households that can absorb a bill that varies materially month to month, and it does not suit everyone.
The question to ask yourself
Could you absorb the worst figure in the row that matches your usage, without it causing real difficulty? If the honest answer is no, wholesale pricing is the wrong product for you and we would rather say so now than in July. Powerswitch, run by Consumer NZ, and Billy, run by the Electricity Authority, are both free and both independent, and for a lot of households one of their answers will be better than ours.
All figures on this page exclude GST.
See what this would cost you
These are our published numbers. What matters is what they do to your bill.
Send us a recent power bill and we will price that same usage against the actual half-hourly market, so you see the difference on your own consumption rather than an average. It is free, it takes a couple of days, and it commits you to nothing.
If it stacks up, choosing your term and seeing your first invoice is the step after that.