I’ll first outline the funding and future research requirements for each technology to be viable in the long-term future:

Energy resource Production costs Research requirements
Solar The manufacture of solar cells, and installing them on land - this could include subsidies to encourage generation at above cost price. Increasing the efficiency of solar cells: current cells have a maximum efficiency of 35% due to their design, however China’s factories only produce cells 19% efficient. Both improvements in manufacturing and new designs with high theoretical efficiency are needed. Storage of generated electricity is also a problem, as solar panels generate only during the day, and produce most output during summer. A means of storing summer production for use in winter is needed.
Nuclear The building of new nuclear power stations is the main new cost. The new Hinkley Point power station is now projected to cost ~£25Bn to build. Fusion technology promises clean electricity, with far less harmful by-products, which are industrially useful. Thorium power generation is also seeing increased attention as a post-uranium fuel source - until now very little research has been performed so the technology is where current nuclear technology was in the 50s.

The problem we now face globally, and more acutely in the UK, is that our current power stations are nearing the end of the operating lives. The UK the government has committed to closing all coal-burning station by 2025, and nuclear stations are in some cases operating beyond their designed lifespans and will start to go off-grid over the next decade. These two sources provided a base capacity to meet the base load on the grid. Whilst gas powered stations can take over this to some extent, we do not have the capacity currently installed for a full transition.

Renewables like solar and wind provide a variable output that does not necessarily match energy demands. Solar in the UK exemplifies this, we want lights/cooking/heating in the evenings when it’s dark. In places such as the US, solar is more useful as it can counterbalance the load caused by air conditioning during the day. We currently do not have storage technologies that can smooth out the fluctuations in generation from wind and solar for them to be able to be used more widely. Already solar farm operators in the UK are finding out the hard way that the grid doesn’t have to buy power from them if it can’t be used (you can’t suddenly lower the output of large power stations if it suddenly becomes sunny).

Solar power also suffers from another shortcoming: we simply don’t have enough land to cover to get enough generating capacity. A 100kmx100km area in Utah (which is mostly desert and very sunny) could power the whole USA, but in cloudy and crowded Europe this is not practical. In urban areas solar panels could be fitted to the exteriors of buildings instead of roofs or glass walls - if we can’t go 100% solar we surely can use wasted space in urban design.

Nuclear power offers a source of base-load power and also does not produce CO2. It also has been proven to work commercially in power stations which are currently operating. The contention comes with the cost of decommissioning and the consequences of an accident. The design that will/may be used at Hinkley is a new French/German design that should be fail-safe (the designs used in Fukushima and Chernobyl were fail-dangerous), however it is one of the first being built, so a lot of things need to get resolved on site during construction that may look fine on paper - this is one thing that contributes to the huge cost.

With the right development solar can be a useful component of our energy supply, but it will need money and time to get there; time of which we are rapidly running out. Current nuclear technology can provide the power that we need in the time that we have. I think that a dash to nuclear to act as a stop-gap until we can deploy reliable and efficient renewable sources is a realistic solution. It should also be pointed out that other power generation schemes such as tidal and geothermal offer the same long-term reliability and base-load generating capacity that we need, and we already have the technology to realize them efficiently. These could be a third path instead of solar or nuclear.