As a corollary to my previous post on Mega Watt Design, where I illucidated the 7 steps to designing and implementing a mega watt site, here is the next step in the process, namely, Site Engineering. This is a very critical part of the whole process where the site is engineered according to the survey report and equipment chosen to reflect the basis of the engineering process. Here, listed below are the two critical components of site engineering :
Site Engineering Basics
1. Identify constraints with setting up foundations for the PV racks.
2. Identify Differential setting of the landscape or the slope, whether it would change
once the racks are fitted onto the foundation.
Though the above may sound complicated, it is easy as a daisy for a Site Engineer to figure this one out, and here is how we overcome the constraints :
1. Proper PV Selection.
2. Proper System Design.
Selecting the proper PV process and Proper System Design require that we start with the Site Preparation Engineering Process, the report of which has been seen in the site survey which analysed and deduced the soil composition and the lay of the land, the Site Preparation Engineering Process consists of the following parts :
Site Engineering Process
1. Clearing up the site.
2. Filling and Grading.
3. Compaction.
4. Tree roots of retrofit sites hold the soil together and will require a strategy to pull them out, for instance the tree trunk will need to be cut at the cap level.
4. Site will have to be graded and filled with top soil to even out the slope in places to achieve uniform cap depth.
5. It may not always be necessary to get a zero slope.
6. After it has been graded it may be necessary to be compacted to provide a solid base for the solar array.
Once the necessary Site Engineering has happened comes the interesting part, the PV Equipment and Drawing board design :
Listed below are the PV system configurations available at low cost in the market today :
PV System Configurations
1. Fixed Tilt (rack mounted with the panels installed to a fixed angle)
Lighter in weight/less expensive/produce less energy per KW
2. Single Axis Tracking Mounting Systems
Track the sun around one axis.
Use an actuator system that rotates an axle.
Are Heavier/more expensive/produce more energy per kW.
Two other criterion for determining PV System Configuration is Pier Depth and differential settlement.
Installing a fixed tilt system
1. Pier and Footing Configuration
Holes drilled in the soil concrete footings poured into the bottom of the hole
then piers attached to the concrete footings and racks attached to the piers.
The depth of the pier is determined by the dead weight point loads supported by the piers and footings. Typically the pier depth can be as less as 3 feet particularly if light
weight panels are used.
As an alternative a concrete slab could be poured to the entire length and width of the of the solar array and then mounting the array on it. This would increase the cost of the project as also weight to the surface.
2. The Type of PV panel
Mono/Poly Silicon
higher efficiency/weigh more/cost more per watt
Thin Films
lower efficiency/weigh less/cost less per watt
3. Wind Loading
Industry standard is 120 mph winds.
Piers and racks of significant gauge steel to withstand high wind.
Designing the mounting structures so that the panels are mounted
closed to ground can help mitigate the damage from high winds.
These factors, if taken into consideration and evolved well enough will give a long lasting PV System that will have the benefits accruing to the customer. In my next post I will go more specifically into the actual design of the components for the Megawatt park.
I am but a novice in the field and the purpose is to write a book on Solar Sales, any information with regards that you might want to pass along, as well any mention of what you intend this book to look like will be deeply appreciated. I am available at info@freshenergy.co or maninder.s.kumar@gmail.com
Site Engineering Basics
1. Identify constraints with setting up foundations for the PV racks.
2. Identify Differential setting of the landscape or the slope, whether it would change
once the racks are fitted onto the foundation.
Though the above may sound complicated, it is easy as a daisy for a Site Engineer to figure this one out, and here is how we overcome the constraints :
1. Proper PV Selection.
2. Proper System Design.
Selecting the proper PV process and Proper System Design require that we start with the Site Preparation Engineering Process, the report of which has been seen in the site survey which analysed and deduced the soil composition and the lay of the land, the Site Preparation Engineering Process consists of the following parts :
Site Engineering Process
1. Clearing up the site.
2. Filling and Grading.
3. Compaction.
4. Tree roots of retrofit sites hold the soil together and will require a strategy to pull them out, for instance the tree trunk will need to be cut at the cap level.
4. Site will have to be graded and filled with top soil to even out the slope in places to achieve uniform cap depth.
5. It may not always be necessary to get a zero slope.
6. After it has been graded it may be necessary to be compacted to provide a solid base for the solar array.
Once the necessary Site Engineering has happened comes the interesting part, the PV Equipment and Drawing board design :
Listed below are the PV system configurations available at low cost in the market today :
PV System Configurations
1. Fixed Tilt (rack mounted with the panels installed to a fixed angle)
Lighter in weight/less expensive/produce less energy per KW
2. Single Axis Tracking Mounting Systems
Track the sun around one axis.
Use an actuator system that rotates an axle.
Are Heavier/more expensive/produce more energy per kW.
Two other criterion for determining PV System Configuration is Pier Depth and differential settlement.
Installing a fixed tilt system
1. Pier and Footing Configuration
Holes drilled in the soil concrete footings poured into the bottom of the hole
then piers attached to the concrete footings and racks attached to the piers.
The depth of the pier is determined by the dead weight point loads supported by the piers and footings. Typically the pier depth can be as less as 3 feet particularly if light
weight panels are used.
As an alternative a concrete slab could be poured to the entire length and width of the of the solar array and then mounting the array on it. This would increase the cost of the project as also weight to the surface.
2. The Type of PV panel
Mono/Poly Silicon
higher efficiency/weigh more/cost more per watt
Thin Films
lower efficiency/weigh less/cost less per watt
3. Wind Loading
Industry standard is 120 mph winds.
Piers and racks of significant gauge steel to withstand high wind.
Designing the mounting structures so that the panels are mounted
closed to ground can help mitigate the damage from high winds.
These factors, if taken into consideration and evolved well enough will give a long lasting PV System that will have the benefits accruing to the customer. In my next post I will go more specifically into the actual design of the components for the Megawatt park.
I am but a novice in the field and the purpose is to write a book on Solar Sales, any information with regards that you might want to pass along, as well any mention of what you intend this book to look like will be deeply appreciated. I am available at info@freshenergy.co or maninder.s.kumar@gmail.com
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