Vancouver has a lot of housing stock from the 1940s, much of it built quickly for shipyard workers and much of it still standing because it was framed with old-growth lumber. These homes are better candidates for solar than people expect. But the surprises are real, and they are almost never on the roof. They are in the attic and at the electrical panel.
Here is what we actually find when we go up there, and what each finding means for your project and your budget.
The electrical panel is the first thing we look at
A solar array has to land somewhere electrically. On a house of this era the service panel has often been replaced once already, sometimes well and sometimes not. What we are checking is capacity, physical space for a breaker, the condition of the bus, and whether the panel is one of the brands that no longer has a listed breaker available.
A panel upgrade is common enough on homes of this age that you should budget for the possibility rather than be surprised by it, and rare enough that you should not assume it. What decides it is specific to your house:
- Service capacity. Many homes of this era were built with 60 or 100 amp service. Some were upgraded decades ago, some were not.
- Physical space for a breaker. A panel can have adequate capacity and still be full.
- Busbar rating versus the solar breaker. This is the calculation that most often forces the issue, and it is not something you can eyeball.
- The brand. A few panel makes no longer have listed breakers available, which effectively forces a replacement regardless of capacity.
The important thing is not the odds. It is that a competent installer identifies this during the site survey and puts it in the quote, rather than raising it as a change order once the permit is filed and you are committed.
If an upgrade is needed it is not a reason to abandon solar. It is a reason to know about it before you sign anything, because it belongs in the quote rather than appearing as a change order after the permit.
Knob and tube: what it does and does not mean
Original knob-and-tube wiring still exists in some homes of this age, usually in pockets rather than throughout, and usually in the circuits nobody has had a reason to touch. Its presence does not automatically block a solar project, because the solar circuit is new work in modern cable back to the panel. What it can affect is insurance, the scope of any panel work, and what an inspector wants to see while the electrical permit is open.
Knob-and-tube turns up in homes of this era, usually in pockets rather than throughout, and usually in the circuits nobody has had a reason to touch. It is far less common than it was twenty years ago, because most homes have had at least partial rewiring somewhere along the way.
Its presence does not automatically block a solar project. The solar circuit is new work in modern cable back to the panel, so it does not run through the old wiring. What it can affect is three things worth knowing about before you sign:
- Insurance. Some carriers have views about active knob-and-tube, and adding solar can prompt a policy conversation you were not expecting.
- Inspection scope. What an inspector wants to see while the electrical permit is open is at their discretion.
- Panel work. If the service panel is being replaced anyway, existing wiring becomes part of that conversation.
Ask your installer directly whether they found any, and what they think it means for your project. It is a fair question and the answer should be specific.
Insulation, and why the attic visit matters at all
People assume the attic inspection is about the roof structure. It is partly that. It is also about everything a solar installer will disturb: existing wiring runs, junction boxes that were never covered, bathroom fans venting into the attic instead of outside, and insulation that has been compressed, displaced or partly removed by decades of other trades working up there.
This matters for a practical reason. If your attic is under-insulated, the cheapest kilowatt-hour available to you is the one you never use. A system sized against a heating load you could have halved is a more expensive system than you needed.
The framing is usually the good news
Roof framing from this period is frequently better than modern equivalents in raw lumber terms: actual dimensional two-by-fours, tight grain, old-growth stock. What varies is spacing, span, the number of roofing layers that have accumulated, and whether previous work has cut or notched anything structural.
What we are looking for is straightforward. Sound rafters, no rot at the eaves, no more roofing layers than the structure should carry, and no surprises where the attachments will land.
Most homes of this era pass a structural check without needing reinforcement. Old-growth framing is genuinely robust, and a modern array adds roughly two and a half to three pounds per square foot — less than a second layer of shingles, which many of these roofs have already carried.
What causes a problem is rarely the original framing. It is what has happened since:
- Accumulated roofing layers, which eat into the available capacity.
- Previous work that cut or notched a rafter for a vent, a flue or a bathroom fan.
- Rot at the eaves, usually where a gutter has failed quietly for years.
- An addition framed to a different standard than the original house.
None of that is visible from a satellite image or from the street, which is the entire argument for someone physically going into the attic before you are given a price.
The roof itself, and the sequencing question
The one genuinely expensive mistake on a house of this age is installing an array onto a roof with a few years left in it. Removing and reinstalling an array to re-roof underneath is a real cost that buys you nothing. If the roof is within roughly five years of replacement, replace it first and treat that as part of the project rather than as a separate future problem.
What none of this changes
An older home is not a worse solar home. It is a home where more of the answer comes from an hour in the attic than from a satellite image. Any company that can quote your house without looking inside it is quoting a model of your house, not your house.
Can you put solar panels on a 1940s house?
Usually yes. Roof framing from that era is often structurally sound, and the more common constraints are the electrical panel, the remaining life of the roof covering, and shading from mature trees rather than the structure itself.
Does knob and tube wiring stop you getting solar?
Not by itself. The solar circuit is new work in modern cable back to the service panel. Existing knob-and-tube can still affect insurance, inspection scope and any panel work, so it needs to be identified before the quote is final rather than after.
Will I need an electrical panel upgrade for solar?
It depends on your panel’s capacity, available breaker space and condition. It is a common finding on older homes and a normal part of a solar project when needed. The important thing is that it is identified during the site survey and included in the quote.
Should I replace my roof before installing solar?
If the roof has roughly five years or less of life left, yes. Removing and reinstalling an array later to re-roof underneath costs real money and delivers nothing, so the sequencing is worth getting right the first time.
Do you need to go into the attic to quote solar?
For an accurate quote on an older home, yes. Rafter condition, existing wiring, insulation and vent runs are not visible from satellite imagery or from the street, and each of them can change the design.
Are older homes more expensive to install solar on?
Sometimes, and the difference is almost always electrical rather than structural. A panel upgrade is the most common added cost, which is why identifying it early matters more than the age of the house itself.
Own an older Vancouver home and want to know what is actually up there? Call us at 360-313-7190 or request a free quote.
