Potatoes and Photovoltaic Performance

Spring 2020 (March-April-May) was the sunniest since records began in 1929 according to the Met Office. This immediately followed the wettest February since rainfall records began in 1862 and it is very likely to be the driest May in England since 1896 (it is 30th May as I write this). And let’s not forget that in Hereford we had 2 frost days in May (12th and 14th) which was a new experience for me in this part of the world.

Although these unusual weather patterns cannot be directly attributed to climate change, our understanding is that we can expect more of these weather extremes as the planet warms.

The Potato Patch

Weather extremes do present challenges to the gardener. My potato patch certainly suffered some frost damage (Figure 1) although the plants in potato bags seemed to escape (Figure 2). My Davis weather station recorded a temperature of 0 °C (measured six foot above ground) on both frost days so at ground level the temperature was probably just below freezing.

Potatoes during frost
Figure 1

Potato bags
Figure 2

Currently, the main issue in the garden is lack of rainfall. Our rainbutts (2000 litres) have run dry and we are having to use our metered water supply.

Photovoltaic Panels

The number of ‘clear blue sky’ days during Spring 2020 has been amazing. Has this been due, in part, to reduced air traffic during the Covid-19 lockdown? The record-breaking sunshine, as noted by the Met Office, has also delivered record-breaking electricity production from my PV roof panels (Table 1).

Table 1: PV Generation (kWh) for Spring 2020

374 383 515 1272 
 2013299 477 512 1288 
 2014344 443 510 1297 
 2015351 563 654 1568 
 2016343 497 573 1413 
 2017366 483 496 1345 
 2018303 409 550 1262 
 2019384 509 582 1475 
 2020439 582 700 *1721 

* Provisional value calculated from current value (519) on 30/5/20 and projected weather forecast up to 8/6/20. Note: monthly PV generation data reported from 9th of the month to 8th of following month (e.g. March data is from 9th March to 8th April inclusive).

2020 set records for highest ever PV generation for March, April and May. Spring (MAM) 2020 PV output was 10% more than the previous highest (2015) and 26% higher than the mean for the previous 8 years. In fact, the differences should be slightly larger because I estimate PV performance has, for example, dropped about 4% since 2015.

1 comment:

  1. The May 2020 generation figure was 713 kWh, a little higher than my estimate. This is the highest figure for any calendar month in the 15+ years these solar panels have been operating (December 2005). In a later post I will compare PV output with sunshine data.


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