Mike Rolls says we should think about the data that will be needed to understand energy consumption in a highly distributed, and partly off-grid, system

 

Energy efficiency and encouraging decentralised low-carbon energy sources for heat and electricity are rising on the policy agenda.  Distributed power generation reduces demand on central systems and avoids distribution losses, but how can we maintain a true picture of consumption as the number of small-scale generators grows?
Small scale renewables such as solar PV are metered for payment of feed-in tariffs, so production can be gleaned from the generation meters. Net and gross end-use consumption can be analysed for the metering period. Planners and policymakers need the former for network development and generation investment, but the latter is the real measure of energy consumption and efficiency.  Very few properties are currently completely off-grid and so they make little difference to the statistics for energy use.  Even then, they would normally have to buy fuel and so are counted in UK primary energy consumption.  Any renewables would be metered for FiTs or the RHI and are counted unless they claim no support, such as using local wood for heat.
At the moment small solar PV accounts for 2% of electricity demand and about 3% of installed capacity (without contributing to winter peaks). But if the price of small scale solar PV falls significantly – so that generation cost are below retail electricity prices  – then the volume should continue to grow apace, even without subsidy.  If it is then permitted to be unmetered, because there is no payment, we might be left only with net import/export kWh statistics from property meters.  The sole measure of capacity deployment might be panel sales volume or any installation reporting requirements to the local distribution network operator.
The likely overall effect on the power system as a whole can be modelled against volume assumptions. But I am concerned that we will simply not know how much power is being generated and used, unless all generation is metered and reported even if it is receiving no subsidy.
If metering and reporting costs are high then it is clearly not sensible to insist on it – we do not want to kill the low carbon investment we are trying to encourage. But without some form of reporting the data gap would grow with time.
Once decent smart meters are installed, one might hope that non-fiscal generation meters linked to the property’s smart meter could be used to satisfy the need for statistical and perhaps even real-time data at low cost.    But what about the impact of time-shifting with batteries under the control of the occupier or his computer, which cannot be modelled centrally in the same way as the natural output of solar cells?
If cheaper unsupported micro CHP becomes prevalent, we would know the metered gas consumption but would not know how much power is generated and consumed.  Should we care as long as carbon-intensive primary energy sources for both heat and power are measured and regulated? Would any mandatory non-fiscal reporting be accused of contravening basic freedoms?
We are clearly some way from having lots of unmeasured input to the system. But perhaps it is time to debate whether we needs to put something in place to avoid a data gap big enough to be significant in assessing our overall energy consumption – and undermining some of the potential benefits of a smarter network.

 

Mike Rolls was previously with Siemens and is now honorary vice president, Association for Distributed Energy and Energy Industries Council

 

Published in the March issue of New Power