For those who work in the industry - how do you shield against this sort of thing when you are designing/building a spacecraft, and what's the knock-on effect? Presumably there's a payload hit if you're using heavier materials...
The Universe is not only stranger than we imagine, it's stranger than we can imagine.
How spacecraft engineering copes with solar events varies greatly with mission requirements and constraints.
Statistically we plan on an average of about six significant events per year, with additional statistical modeling to estimate the likelihood that any one event will be aimed so as to affect some particular mission.
The most elementary design policy is simply to say your spacecraft will work until the Sun cooks it. That is, we don't design anything specifically to accommodate solar particle loads.
The mechanical and electrical design of spacecraft is a highly demanding art that incorporates requirements for rigidity, structural efficiency, mass distribution, thermal loading, pointing, duty cycle, and so forth. Often things like thermal properties and mass distribution will drive the design, competing almost overwhelmingly against the arrangement of components such that sufficient mass is placed between the particle front and delicate components.
Some components such as computers can be obtained these days as COTS items incorporating enclosures that satisfy reasonable thermal, mechanical, and radiation tolerance.
Where the other mechanical design constraints allow, radiation sensitive components can be placed behind sufficient mass, whether it be explicit shielding such as high-density polyethylene or dual-purpose components, such as RCS fuel tanks. Even sufficiently robust elements of the spacecraft chassis can be pressed into service as shielding.
Even the most radiation-agnostic design will have some vector in the spacecraft coordinate system that is the least susceptible to radiation damage overall, and a rudimentary safe mode can be implemented by commanding the spacecraft to the attitude that aligns that most-survivable direction to the highest particle flux vector for the duration of the exposure. This is the method used by Apollo -- the stack would have been oriented so that the bulk of the Service Module stood between the Command Module cabin and the particle front.
Any engineered safe mode involves stowing sensitive components and/or rotating the spacecraft to minimize the exposure of sensitive components to the particle flux. Since solar panels are sensitive to particle radiation, there is often also a power-management component to spacecraft safing. In that instance, the spacecraft operates on reduced power from batteries while the solar arrays are stowed. Then after a predetermined interval, the arrays are redeployed and the spacecraft is returned to its nominal attitude and power profile.
Keep in mind that safing a spacecraft is not always safe. Solar panel stowage and deployment is considered a mechanically risky operation due to the delicacy of the assembly and the tendency of mechanical interfaces to become unreliable following a prolonged space soak.
There are obviously several design and operation tradeoffs that arise from radiation management. There is no one policy that applies to the whole industry; there is merely a vocabulary of predictive models and design and operational patterns that can be drawn upon for each particular mission.