The background photo shows an art installation in Ottawa that looks heliostat-inspired.

Relevance:

“Residential energy use is responsible for about 20% of total greenhouse gas (GHG) emissions in the US.”

From

https://wcec.ucdavis.edu/analysis-of-greenhouse-gas-emissions-from-residential-heating-technologies-in-usa-2/

Last accessed 6 Nov 2022.

Figure not found in a peer reviewed source but probably partly based on

Dichter, N., & Aboud, A. (2020). Analysis of Greenhouse Gas Emissions from Residential Heating Technologies in the USA. UC Davis Western Cooling Efficiency Center. https://wcec.ucdavis.edu/wp-content/uploads/GHG-Emissions-from-Residential-

Comment:

The carbon emissions on these shores appear to be roughly evenly distributed across sectors. (See: “Overview of greenhouse gasses”, publisher: EPA, govt, USA) Therefore, meaningful reductions will require a combination of collective action and household-level action: neither will suffice by itself.

From Zig Ziglar, we have this: “Whatever you need to do, do a little every day.”

Safety: 

Do not use warped plywood for the reflector or it may focus sunlight and cause a fire. Replace or reverse it if it becomes warped. Waterproof it carefully before putting it into service. Inspect for foci periodically and after each rain and renew or reverse the reflector if any are found.

To put my safety note in perspective, products already on the market have the same issue, like this concave, magnifying shaving mirror. The combination of concave, reflector, and sunlight is to be avoided.

Linseed oil safety:

X

https://www.simplemost.com/linseed-oil-can-fire-hazard-need-know-stay-safe/

X

https://www.flinnsci.com/sds_450-linseed-oil/sds_450/

Build, miscellaneous: 
I use push-rods made of wooden dowels to set the angles. These can be marked with a pencil to show the daily series of settings that must be reproduced by a future computerized controller. The dowel can be rotated to get a fresh surface for marking the results for the following month. In future, each dowel will be replaced by some electric device such as a car's cable-type power window regulator, illustrated below. The system diagram shown in the gallery is proposed and not built.

A car window regulator
Dowel hardware
The manual clutch assemblies for the fixed ends, which are based on conduit clamps. The adjustable ends are very similar. In addition, each dowel passes through a guide assembly with a slip fit. The dowels have one-hole sections of mending plates on the ends to keep them from getting pulled out of the clutch by gusts of wind. 
Tools and raw materials. The long cuts were made in-store for free (a Home Depot service). Most of the other cuts used the miter box.

The finished, waterproofed project, shown as a kit reassembled on the reflector. The final step was re-drilling the bigger holes to remove gunk and fiber, because they need a slip fit with the fasteners.
Some of the hardware I used, showing the pieces that dictated the details of pilot hole placement. The hole data I give below in a spreadsheet will have to be adjusted if these specific parts are not used.


The above two pictures show how I braced the prototype to reduce wobble. In each picture, the point of interest is near the center. One brace is a bent mending plate. Results satisfactory.

Weather test:

After 4 months outdoors, Nov-Mar, the project remained mechanically sound with no rust. The reflector board was somewhat dusty but not noticeably warped. Some areas of end grain facing upwards were split or delaminated, so such surfaces need to be double-sealed. The second coat on these areas was outdoor spar urethane, oil based. Before applying, I wiped down with a Varsol-moistened rag in lieu of sanding, wearing "Mr. Clean" brand gloves, which did not pucker when a drop of Varsol was left on them for 7 min. A second coat of urethane was applied to upward end grain located below the snow line (shown below, before urethane application).

Six pavers of ballast were used to prevent the project from upsetting in gusty March winds; three did not suffice. Wind vibration seems to unlock some of the casters.

Water damage, worst spot

With three pavers of ballast, the casters locked, and the reflector vertical, the project blows over when the wind is gusting to 40 km/h (25 mph) or more.