Volcanic eruption to reduce solar output?

CALLD

Is it true that large volcanic eruptions (like the one that just happened in Chile) could perhaps chop up to 10% of my solar production for several years?

BB.

It can... But will it, not very common unless a very large eruption or you are down wind of the ash cloud:

http://rredc.nrel.gov/solar/pubs/shining/chap3.html

Both man-made and naturally occurring events can limit the amount of solar radiation at the earth's surface. Urban air pollution, smoke from forest fires, and airborne ash resulting from volcanic activity reduce the solar resource by increasing the scattering and absorption of solar radiation. This has a larger impact on radiation coming in a direct line from the sun (direct beam) than on the total (global) solar radiation. Some of the direct beam radiation is scattered toward earth and is called diffuse (sky) radiation (global = direct + diffuse). Consequently, concentrators that use only direct beam solar radiation are more adversely affected than collectors that use global solar radiation. On a day with severely polluted air (smog alert), the direct beam solar radiation can be reduced by 40%, whereas the global solar radiation is reduced by 15% to 25%. A large volcanic eruption may decrease, over a large portion of the earth, the direct beam solar radiation by 20% and the global solar radiation by nearly 10% for 6 months to 2 years. As the volcanic ash falls out of the atmosphere, the effect is diminished, but complete removal of the ash may take several years.

https://www.ipcc.ch/publications_and_data/ar4/wg1/en/tssts-2-4.html

Explosive volcanic eruptions greatly increase the concentration of stratospheric sulphate aerosols. A single eruption can thereby cool global mean climate for a few years. Volcanic aerosols perturb both the stratosphere and surface/troposphere radiative energy budgets and climate in an episodic manner, and many past events are evident in ice core observations of sulphate as well as temperature records. There have been no explosive volcanic events since the 1991 Mt. Pinatubo eruption capable of injecting significant material to the stratosphere. However, the potential exists for volcanic eruptions much larger than the 1991 Mt. Pinatubo eruption, which could produce larger radiative forcing and longer-term cooling of the climate system. {2.7, 6.4, 6.6, 9.2}

Year Without a Summer

The year 1816 is known as the Year Without a Summer (also the Poverty Year, the Summer that Never Was, Year There Was No Summer, and Eighteen Hundred and Froze to Death^[1]), because of severe climate abnormalities that caused average global temperatures to decrease by 0.4–0.7 °C (0.7–1.3 °F).^[2] This resulted in major food shortages across the Northern Hemisphere.^[3] Evidence suggests the anomaly was predominantly a volcanic winter event caused by the massive 1815 eruption of Mount Tambora in the Dutch East Indies (Indonesia), the largest eruption in at least 1,300 years. The Earth had already been in a centuries-long period, since the 14th century, of global cooling known today as the Little Ice Age, which itself caused considerable agricultural distress in Europe as a whole during its onset; the Little Ice Age's existing cooling was solely as a potentially aggravating factor, as the eruption of Tambora occurred during the Little Ice Age's concluding decades.^[4]

-Bill