About

Off-Grid Solar is a reference guide to designing and living with off-grid power systems, aimed at cabins, homesteads, and tiny houses, plus backup power for homes that do have utility service.

It is written and maintained by Matt.

How this site is put together

I am not a licensed electrician, and this site does not pretend otherwise. What it does is read the primary sources carefully and show its working.

That means:

• Electrical figures come from the code, not from other blogs. Wire sizing follows the NEC (NFPA 70): conductor resistance from Chapter 9 Table 8, ampacity from Table 310.16, small-conductor limits from 240.4(D). Where a number comes from a standard, the page says which one.
• Product specifications come from manufacturer datasheets, not from marketplace listings, which are frequently wrong about capacity and chemistry.
• Where something is an estimate, it is labeled as an estimate. System efficiency factors, cycle life ranges, and cost comparisons are all approximations, and pages say so rather than presenting a range as a precise figure.
• Where a calculation is simplified, the page says what it leaves out. The wire gauge tool, for example, does not model ambient temperature correction, conduit bundling, or terminal temperature limits. All three make the real answer thicker, so the result is a floor rather than a final answer, and the page states that.

If you want to know why a number on this site is what it is, the answer should be on the page. If it is not, that is a fault worth reporting.

Corrections

Getting this wrong has real consequences. Undersized wire starts fires, and a battery bank sized on optimistic numbers leaves someone without power in February.

If you find an error, tell me. Corrections are made promptly and the page’s updated date is changed so you can see it happened.

What this site is not

It is not a shop. Nothing is sold here, and there is no installation service.

It is not a substitute for a licensed electrician or for your local inspector. Anything permanently installed in a building is subject to code requirements that vary by jurisdiction. See the disclaimer.

About this domain

This site is published at thesolarshop.net. That domain previously belonged to The Solar Shop, an alternative energy business in Tonasket, Washington, which is not connected with this site in any way.

Off-Grid Solar is an independent, unaffiliated publication. It is not a continuation of that business, has no relationship with its former owner, and does not offer the sales, service, or installation that business provided. If you are looking for that company, this is not it.

Making money

Some pages carry affiliate links, and buying through them earns a commission at no extra cost to you. That is what pays for the site. It does not decide what gets recommended. The affiliate disclosure explains how this works in full.