Wednesday 4 October 2023

Is Solar the Only Answer?

Why is solar important?

Under the feed-in tariff scheme which ended in 2020, 79.3% of all the installed capacity was solar, accounting for 98.8% of all installations (source: Central FIT Register, Ofgem).

The period since the pandemic has been turbulent with much greater uncertainty around the availability of kit and its associated cost to the extent that the average installed solar cost/kW has increased by 43% from pre-pandemic levels (source: MCS).

However, combined with excruciatingly high wholesale power and gas prices the business case for solar has never been stronger.

Combining multiple technologies: Solar and battery

Personally, I’m a big fan of solar PV. I installed it in 2015 at home (Edinburgh) and it has already paid back that initial investment and continues to generate free electricity, most of which is stored for when it’s needed (not withstanding a rather damp squib of a summer).

But is solar the only answer, what about when the sun isn’t shining, and we need heat from renewable low-carbon sources?

Combining solar with a battery is an obvious option. Excess generation is stored during the day and used at night. But determining what size of battery should be considered to maximise the return on investment isn't straightforward, particularly if the capital is constrained. The main electricity cost savings are from "load shifting" but capacity costs can also be reduced through "peak shaving". The Targeted Charging Review threw up some new challenges. Prima facie removing some of the benefit from load shifting whilst presenting a tantalising capacity related step reduction in DUoS rates.

Perceived wisdom for the last few years is that batteries only really stack up when they are also used to provide National Grid with ancillary services to help ensure grid frequency at 50Hz (frequency response) and to provide sufficient spare capacity when needed (capacity market).

Combining multiple technologies: Solar, heat pumps and wind

But what about other combinations of technologies?

The most common technology combinations we see customers model are solar PV with a heat pump, usually air source due to the relative ease of installation.

Along with transport, decarbonisation of heat is a tough challenge, particularly when high-grade heat is needed. Heat pumps will play a significant role in meeting the UK’s net zero targets; the ideal scenario being heat pumps powered by renewable electricity. Whilst high temperature heat pumps are being developed to meet domestic hot water needs and even for industrial processes, their efficiency falls dramatically.

Solar water heaters are an option to sit alongside a heat pump but a backup system is still recommended for particularly cold days in the darker winter months.

And it’s in the winter months that self-generated renewable electricity from solar is very limited. A great option is co-located wind which generally produces more power in the winter months and doesn’t depend on sunlight.

However, wind in the built environment is not a sensible option due to the turbulent air currents that buildings create.

How can OnGen Expert help?

With so many variables, it’s easy to see why people focus on a single technology but it’s also the reason OnGen Expert has been developed, to consider multiple technology options quickly and accurately at the feasibility stage to determine the appropriate size of a system and identify potential constraints before wasting time and resources at the development phase.