Part I: Start HereChapter 1. Reading Your Site
Picking Your First Project: A Decision Flowchart
A short path from your site and your bills to a first project that matches your tools.
- Difficulty
- Beginner
- Cost
- Free
The first project should be the one that attacks the largest loss you can actually reach, with a failure that stays small. That is usually not the project that looks most like solar. A leaky attic hatch moves more heat than a window heater, and a west window without shade makes an air conditioner work harder than a missing collector does.
Use this page after you have a site sketch, a sense of true south, and a look at the bills or at least a winter of memory. The why-build page is the accounting if you are arguing with yourself about payback.
Difficulty
- Level
- Beginner
- Time
- Half an hour once the sketch exists
- Skills
- Being willing to skip a project that is exciting and wrong
Cost estimate
Free
The flowchart spends nothing. The branches point at projects whose costs are written on their own pages.
Materials
| Item | Qty | Notes |
|---|---|---|
| Site sketch | 1 | South surfaces, shade, and which rooms are behind them. |
| A heating or electric bill, even a rough one | 1 | So you know whether the prize is heat, hot water, or kilowatt-hours. |
| A freeze answer | 1 | Has a hose bib frozen here? That answer deletes some water projects. |
Walk the questions in order
Does the house leak, and have you never sealed the ceiling? If the heat-loss sketch shows the ceiling or the air leaks near the top, or if you can feel a draft at the attic hatch, do the air sealing weekend before you build a collector. You may still build the collector afterward. You will understand it better, and the house will need less of it.
Do the west windows overheat in summer? Shade them. Exterior shade is the cooling project with the least machinery. The shade guide is the geometry. Do not solve a west window with a collector on the south wall. That is a different season.
Do you want to build something solar, and is there a sunny south window? Build the window air heater. It is small, it teaches glazing, absorber, and a damper, and you can feel the result the same day. A shop with a sunny south wall can take the wall collector instead, if you are ready for a fan and two holes.
Is hot water a large share of the bill, and does the site never freeze? A batch preheater is the simple water project. If the site freezes, do not build it. Read the layout choice and treat a pumped system as a later project, not a first one. Glycol, drainback pitch, and a roof are a poor place to learn.
Is the electric bill the target, after the obvious waste is gone? Size the array with the PV guide, then stop and take the number to an electrician and the utility. Do not buy modules as the first step, and do not land conductors in a panel as a practice run.
Projects to postpone on purpose
Postpone anything that needs a new electrical service, a roof penetration, a pressurized glycol loop, or a foundation. Postpone a sunspace until you have written whether it is a heater or a greenhouse. Postpone a battery system until the house has a measured load. They are in this book, but they are not first projects.
Also postpone a project whose sunny surface failed the shade map.
Answer the leak question
If you have not looked at the attic hatch, go look. Settle that before you open a catalog.
Answer the summer question
Name the room that is miserable in July. If it has west glass, shade is allowed to be the whole first project.
Pick one solar build only if the first two are handled or honestly small
Window heater, or a batch box where it never freezes, or a plan for PV that stops at the paperwork.
Write the project you are not doing
The rejected branch keeps the next sale flyer from restarting the decision.
Further reading
These links go to outside sources. This book cites them by link and does not copy their words or pictures.
- https://www.builditsolar.com/SiteSurvey/site_survey.htm
- https://www.builditsolar.com/SiteSurvey/FindingSouth.htm
- https://www.builditsolar.com/SiteSurvey/MagDecl.htm
- https://www.builditsolar.com/SiteSurvey/StepByStep.htm
- https://www.builditsolar.com/SiteSurvey/challenges.htm
- https://www.builditsolar.com/GettingStarted/GettingStarted.htm
- https://www.builditsolar.com/GettingStarted/ChoosingProjects.htm
- https://www.builditsolar.com/References/SunChartRS.htm
General education, not a permit or a stamped design. Follow the safety note in the guide, read the safety disclaimer, and hire a licensed trade when the work requires one.