As of August 1, every household with solar pays a facilities charge of $148.83 a month, up from $52.48, whether their system is two kilowatts or 20. Belco calls this solar users paying their “fair share”. The Regulatory Authority, which approved it, says the charge “more accurately reflects the grid access costs they continue to impose on the system”.

However, the Electricity Act requires a customer's bill to show what their own demand costs, and an identical flat charge for all solar customers doesn't achieve that. The Act also requires the authority to promote renewable energy, yet work the numbers on any Bermuda roof and this structure says the opposite: install as little as you can. Is the authority meeting its obligations under the Act?

That isn't to say solar imposes no cost on the grid. Cloud cover swings production minute to minute. Extended cloudy spells and seasonal change swing it over months. The sun doesn't shine at night. The grid has to hold capacity for all of that, and holding it costs money.

Under the old structure, solar customers paid a flat charge of $52.48, set near the middle of the residential range, while most of the grid's fixed costs were recovered through per-kWh rates. A household that draws little from the grid but relies on it being there does not contribute much to the cost of keeping it there, and as solar uptake grows, those costs shift onto the rest of us. I don't have solar. My concern is what this design does to our incentives, and the direction it points us on sustainability and energy independence.

Belco and the RA call this transparent, cost-reflective and fair by usage. Unbundling generation from distribution on our bills delivers the transparency. The facilities fee is where it stops adding up. Section 35(4)(b) of the Electricity Act 2016 requires tariffs to “include information that gives end users proper information regarding the costs that their demand imposes on the licensee's business”.

The RA's own Embedded Cost of Service Study puts 72 per cent of costs as demand-related, 24 per cent customer-related and 4 per cent energy-related. Yet a solar user pays the same $148.83 whether they draw a little or a lot, and cannot manage it down by using less or storing more. It tells us nothing about demand, which is the opposite of fair by usage.

The RA's own diagnosis doesn't lead to a flat rate. The authority’s consultant, Ricardo, noted that solar customers “face lower bills than they would if they were fully reliant on the grid”. With 72 per cent of costs deemed demand-related, the logical conclusion would be to place solar customers in the tier they would have been in, or tie their rates to demand.

Instead, every solar household has been placed in the top bracket, Tier 5. It is defined as 50+ kWh/day of consumption, not reliance. A small household that uses 8kWh/day and installs solar still needs the grid to be ready for 8kWh/day, not 50. Non-solar customers keep their graduated rates. The group the RA says is driving our costs gets one flat charge.

The odd thing is that the data to have made a different decision already exists. Solar customers must have an advanced net meter that reports hourly and Belco fits it at its own expense based on the Interconnection agreement. So precise imports and peaks are already measurable for every solar home, and what the meter records is what you draw from the grid, which is exactly the measure of reliance the RA says it cares about. Tier the charge by metered import or metered peak and the problem disappears. Where there are concerns about older installs, those households could be grandfathered into their pre-installation tier.

The RA says that to limit disruption to customers, it chose the most conservative of the four options its consultant modelled. That is true of every customer except the ones it disrupted. Residential facilities charges rose about 23 per cent across the board for non-solar customers. Solar households? 184 per cent. Is that what the authority considers non-disruptive? It took the gentlest option on the menu and bolted the harshest available treatment of solar onto it. The options that would actually measure demand, the ones Ricardo recommended for the long term and which Belco said it preferred, were postponed to a future review. The charge was not.

The RA's analysis is asserted but never shown. Ricardo writes that “we conducted analysis and assessed that an appropriate starting fixed rate for DG customers could be implemented by” placing them in Tier 5. That is their entire justification for putting solar customers into the same tier as the largest-demand customers. No figure is provided for what a solar household's grid access actually costs.

Commercial and demand equivalents are set at $200 and $250, round numbers of a kind no cost study produces. Ricardo records that the allocation factors were chosen to produce “a 0 per cent change across customer classes”, which suggests the revenue target came first and the rest was fitted to it. Perhaps there is a calculation behind $148.83 that we have not been shown, but it certainly doesn't suggest a decision based on demand.

The Act requires a bill to show customers what their own demand costs, and it requires the authority to promote cleaner energy. A flat charge does neither. The RA needs to scrap it, price by metered import or peak, grandfather existing installs where the data is thin, and publish the analysis behind whatever number replaces it.

I don’t have rooftop solar, I don't own any Bermuda solar businesses and outside of having considered installing solar, I have no stake in the rate outcomes. I do own commercial solar assets in Europe, outside Bermuda which are unaffected by this decision.

• Denis Pitcher is a technologist and former chief fintech adviser to the Government of Bermuda