As you may know from our earlier posts, we’re generating electricity for mod 302 using eighteen 275W solar panels. After noticing significant production dips in our solar panels we did some investigation and learned some interesting information about maintaining solar panels, when they’re ideal for electricity generation, and where they stand in regards to other resources. This is the report on these production dips.
Abstract:
The Solar panels on Mod 302 were experiencing dips in production every day from around 10:45am to 11:30am and 12:45pm to 2:00pm. We believe these production dips were being caused by two tall trees to the south of the building. At the before mentioned times, the sun was hiding behind these trees, thus shading the solar panels and reducing their electricity production.
Analysis:
These dips in production were caused by two different trees. One of these trees was almost directly south of the solar panels and the other tree is generally south east of the solar panels. The sun dips behind the southeastern tree at 10:45am and is fully visible again by 11:45am, the sun then dipped behind the southern tree at about 12:45pm and was fully visible again by 2:00pm. In January of 2014 the 302 solar panels showed an average energy production level of 1.28 kWh. During the dips in production we saw power production decrease to as low as .003 kWh (3 Wh) with a high of about .133 kWh (133 Wh). In February, the 302 solar panels showed an average production level of 1.29 kWh. During the dips in February, we saw a low of about .013 kWh (13 Wh) and a high of about .116 kWh (116 Wh). In February the lowest dip is not as drastic as the lowest dip in January, with a small difference of .01 kWh (10 Wh).
Something important to note about this is the fact that the sun’s altitude angle changes drastically as the seasons change. In the winter you may find the sun at an angle of 20 degrees, but during the spring and summer the sun can reach a maximum of 90. So these production dips are only taking affect in the fall and winter, but during the spring and summer the sun rises high above both trees.
Relevance:
With the growing threats that are being caused by climate change, there is an also growing need for renewable resources that emit low amounts of carbon. Solar panels are one of many ways to attempt to satisfy this need for renewables. Solar panels emit significantly less carbon per kWh than electricity pulled from the grid, exactly how much depends on where you are and the systems used to generate grid electricity. When planning urban environments, if you’re going to use solar radiation as a primary resource, you need to design the urban system to have access to this radiation. This may mean slanted roofs facing the incoming solar radiation, placing windows specifically to capture passive solar heat, or removing trees to make way for incoming solar radiation. Planning urban environments, or altering established ones, to be geared towards using solar radiation is known as “solar zoning.” If we want to build communities that are environmentally friendly and sustainable, we need to plan these communities and their locations to have maximum access to the sun’s incoming energy.
I will make another blog post soon explaining how we dealt with this problem.
This is the link to access the data being collected on the PV solar panels on Mod 302:
https://enlighten.enphaseenergy.com/pv/public_systems/ggfa523388?preview=1
TL;DR
Our solar panels were producing little to no electricity at certain times while the sun was out, we realized it was due to two different trees shading them.
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