I'm working on building a prototype heliostat for the initial goal of shining light (and heat) into the living room.
So far, my concept seems like it's going to work, with some minor modifications.
This first prototype is using nema 17 stepper motors and electronics very similar to what's in 3d printers. These little motors seem to have plenty of torque to push around a square meter of $7 walmart mirrors through a 1:100 worm gear setup. However, it's readily apparent that rigidity is going to be a main concern. You can see how flexible the azimuth joint (1/2in bolt) is compared to the altitude joint (60mm diameter bushing around a wood 2x2). I'm currently rebuilding this using 1.5in pvc pipe and large joints that rotate around the outside of it. The printed parts are made with PLA plus, which has proven to be far better than standard PLA in every way. I don't expect it to be the weak point, but I can always redesign it or CNC some of the joint parts out of metal.
It's hard to find much information about heliostats online. In fact, the website I got the original control software from is gone and must be accessed through the wayback machine. Obviously with the cost of pv panels in freefall, anything commercially made is super expensive in comparison. However thanks to the rise of makers and 3d printing, the cost of the motors and control electronics needed to build a small heliostat has also never been lower. Ordering from china in small quantities of 5-10x, I should be able to get the electronics and motors for under $40 per heliostat. All the motors and electronics in my current prototype I had laying around. One square meter is a good target, as that seems like it's going to be within the capabilities of cheap mass produced nema 17 motors and drivers. Going bigger means a big jump in the cost of the motors and drivers, not to mention the hardware.
I intend this first heliostat to be a prototype for testing viability and longevity. If it works well, and proves to be reliable, I want to build a real solar thermal system with more of them. My eventual dream is to build a solar thermal system to offset the cost of heating my house with propane. I want to build a solar collector that is able to handle concentrated solar power, to heat water in insulated storage tanks that I can pump to heat my house. I figure the chances of me actually getting that far are probably around 20%, but all the steps are fun projects in their own sense and should keep me entertained for a while.
Running the numbers, if I can build heliostats for $100 per square meter, my payback period is somewhere around one year. Based on my smart thermostat heating history from last January, I averaged 150kWh per day of propane heating, at a cost of $23, eww. This means I won't start to hit diminishing returns until around 20 square meters, which is a lot of heliostats. Every little step in this direction can make a difference.
The thermal collector will have to be custom built, as there really aren't any off the shelf products that can handle concentrated solar power. That's fine, as I have a good bit of experience with steam engines that should translate well in this area. For storage, a 330 gallon ibc tote (those big white tanks in steel cages) should hold about 40kWh of heat between 100 and 150F. They're super cheap around here in farm country. Controls and such are no problem, as I have a strong background in industrial automation. I have a nice big ~1/2 acre field at the edge of my yard that I don't do anything with to put this stuff. The whole concept is big but very feasible within my skillset as long as I can build cheap relatively reliable heliostats. My biggest hurdle besides money is just not moving on to some other project.
Speaking of money, I'm sure it would be more cost effective to improve my house. However, my house is a cheap manufactured home from 1990. The walls are thin and it's made of swiss cheese, so I want to put a new house in sometime in the next 3-5 years anyways. So most improvements are either not worth doing with the new house timeline, or even less practical to attempt than my crazy solar idea. At least the previous owners put in a 95% efficient furnace. It's also much easier for me to dink around on this project $20 at a time than it would be to go get a loan and put solar panels in. Besides, this is also mostly for fun.
Future project dreams aside, I'm excited to test my heliostat out. I've got the software working great, and the rotary mechanism design is looking feasible.
So far, my concept seems like it's going to work, with some minor modifications.
This first prototype is using nema 17 stepper motors and electronics very similar to what's in 3d printers. These little motors seem to have plenty of torque to push around a square meter of $7 walmart mirrors through a 1:100 worm gear setup. However, it's readily apparent that rigidity is going to be a main concern. You can see how flexible the azimuth joint (1/2in bolt) is compared to the altitude joint (60mm diameter bushing around a wood 2x2). I'm currently rebuilding this using 1.5in pvc pipe and large joints that rotate around the outside of it. The printed parts are made with PLA plus, which has proven to be far better than standard PLA in every way. I don't expect it to be the weak point, but I can always redesign it or CNC some of the joint parts out of metal.
It's hard to find much information about heliostats online. In fact, the website I got the original control software from is gone and must be accessed through the wayback machine. Obviously with the cost of pv panels in freefall, anything commercially made is super expensive in comparison. However thanks to the rise of makers and 3d printing, the cost of the motors and control electronics needed to build a small heliostat has also never been lower. Ordering from china in small quantities of 5-10x, I should be able to get the electronics and motors for under $40 per heliostat. All the motors and electronics in my current prototype I had laying around. One square meter is a good target, as that seems like it's going to be within the capabilities of cheap mass produced nema 17 motors and drivers. Going bigger means a big jump in the cost of the motors and drivers, not to mention the hardware.
I intend this first heliostat to be a prototype for testing viability and longevity. If it works well, and proves to be reliable, I want to build a real solar thermal system with more of them. My eventual dream is to build a solar thermal system to offset the cost of heating my house with propane. I want to build a solar collector that is able to handle concentrated solar power, to heat water in insulated storage tanks that I can pump to heat my house. I figure the chances of me actually getting that far are probably around 20%, but all the steps are fun projects in their own sense and should keep me entertained for a while.
Running the numbers, if I can build heliostats for $100 per square meter, my payback period is somewhere around one year. Based on my smart thermostat heating history from last January, I averaged 150kWh per day of propane heating, at a cost of $23, eww. This means I won't start to hit diminishing returns until around 20 square meters, which is a lot of heliostats. Every little step in this direction can make a difference.
The thermal collector will have to be custom built, as there really aren't any off the shelf products that can handle concentrated solar power. That's fine, as I have a good bit of experience with steam engines that should translate well in this area. For storage, a 330 gallon ibc tote (those big white tanks in steel cages) should hold about 40kWh of heat between 100 and 150F. They're super cheap around here in farm country. Controls and such are no problem, as I have a strong background in industrial automation. I have a nice big ~1/2 acre field at the edge of my yard that I don't do anything with to put this stuff. The whole concept is big but very feasible within my skillset as long as I can build cheap relatively reliable heliostats. My biggest hurdle besides money is just not moving on to some other project.
Speaking of money, I'm sure it would be more cost effective to improve my house. However, my house is a cheap manufactured home from 1990. The walls are thin and it's made of swiss cheese, so I want to put a new house in sometime in the next 3-5 years anyways. So most improvements are either not worth doing with the new house timeline, or even less practical to attempt than my crazy solar idea. At least the previous owners put in a 95% efficient furnace. It's also much easier for me to dink around on this project $20 at a time than it would be to go get a loan and put solar panels in. Besides, this is also mostly for fun.
Future project dreams aside, I'm excited to test my heliostat out. I've got the software working great, and the rotary mechanism design is looking feasible.
