In a new build, photovoltaics are generally cheaper: scaffolding and planning are there anyway, cables and meter box are dimensioned correctly right away, and in-roof solutions are a real option. Retrofitting is nevertheless the normal case and works economically – the common guideline values are retrofit prices. The most expensive is a third way: the new build that postpones the system to «later» and prepares nothing. (As of: July 2026)
Key points in brief
- A new build saves on everything that is necessary around the technology: scaffolding, roof access, cable routing, electrical planning – the modules themselves cost the same.
- With new builds, the question often no longer arises at all: the federal government requires a solar system on large new buildings, the Canton of Zurich requires own electricity generation for practically all of them.
- Retrofitting means: scaffolding as a separate item, meter box as a potential surprise, roof condition as a preliminary question – all solvable, all priceable.
- Whoever builds new and postpones the system pays twice later: for the scaffolding, for the subsequent routing of cables and for the missed in-roof opportunity.
- Preparation costs little during the structural work – empty conduits, reserves in the meter box and a solar-compatible roof are the cheapest insurance.
Why is the solar system cheaper in a new build?
Because the new build brings the most expensive secondary conditions with it free of charge. A solar system consists of technology – and of everything that is necessary to get it onto the roof and connected to the grid: scaffolding, roof access, cable routing, space in the house distribution, planning and paperwork. In a new build, the scaffolding is already in place anyway, the electrician is already in the house anyway, the cables are routed before the walls are plastered, and the meter box is correctly dimensioned from the start. When retrofitting, each of these points is a separate item.
Added to this is an option that only exists with an open roof: the in-roof system, where the modules replace the roof covering. In a new build, it is offset against the saved tiles; retrospectively, it only makes sense during roof renovation. And finally, the new build factors the system into the construction financing, instead of having to fund it separately later.
The technology itself, by the way, does not get any cheaper: modules, inverter and mounting system cost the same in a new build as in retrofitting. The difference lies entirely in the surrounding work – and that is exactly why it can be planned.
Does the question even arise with new builds anymore?
Increasingly rarely. Since 2025, the federal government requires a solar system on new buildings with more than 300 m² of chargeable building area; the Canton of Zurich goes further and requires own electricity generation for practically all new builds – as a guideline value, 10 W per m² of energy reference area, in practice almost always photovoltaics. The details and exceptions can be found in the article on the solar obligation in Switzerland.
For the question of cost, this means: for new builds in the region, the question is no longer «whether», but «how big». And here we repeat the recommendation from the obligation discussion: treat the requirement as a lower limit, not as a target size. The additional costs from the mandatory minimum to full roof coverage are smaller in a new build than they will ever be again – it is the same crane, the same scaffolding, the same electrician.
What makes retrofitting more expensive – and what does not?
Three items make the difference, and all three are quantifiable. Firstly, the scaffolding: when retrofitting, it is erected specifically for the system – a fixed cost that is proportionately very significant for small systems. Secondly, the house electrics: in older houses, the meter box is the hidden cost factor, because it has to be adapted for the system. Thirdly, the roof condition: if the roof covering needs to be renewed in the foreseeable future, the renovation comes before the system – otherwise you pay twice for dismantling and scaffolding.
Equally important is what does not make retrofitting more expensive: the system itself. The guideline values of CHF 2,000 to 2,800 per kWp describe turnkey systems on existing roofs – retrofitting is the normal case in the Swiss solar market, not the expensive exception. Incentives and tax deduction also tend to speak in favour of existing buildings: the one-off feed-in incentive (EIV) is available in both cases, the tax deduction for the investment, however, is only available for existing buildings in most cantons. Whether the system pays off is decided by consumption anyway – not the year of construction.
The most expensive way: saying «later» in a new build
There is a third variant, and it is the most costly: building new, postponing the system and preparing nothing. Then, a few years later, all the retrofitting items come together – new scaffolding, cables through finished walls, adaptations to a distribution board that was planned without reserves – and the in-roof opportunity is lost, because the new roof covering is already in place and is being drilled into again.
Those who really do not want the system immediately when building a new house – due to budget or priorities – have a smart middle way: prepare instead of postpone. In concrete terms, this means: empty conduits from the roof to the plant room, space reserves in the meter box, structural statics that can support the system, and a roof without small details on the best surface. We recommend the same logic within the system for battery-ready building and for wallbox preparation: the empty conduit during the structural work costs little, the separate construction site later significantly more.
New build and retrofitting in direct comparison
| Item | New build | Retrofitting |
|---|---|---|
| Scaffolding & roof access | already available anyway | separate item |
| Cable routing | laid during structural work | retrospective, complex depending on the house |
| meter box | correctly dimensioned from the start | adaptation possible, site visit clarifies |
| Roof covering | new – in-roof as a real option | condition is a preliminary question; in-roof only during renovation |
| Technology (modules, inverter, mounting) | same | same |
| Incentives | One-off feed-in incentive (EIV); mandatory share depending on canton | One-off feed-in incentive (EIV); tax deduction mostly only for existing buildings |
| Planning & administration | integrated into the construction project | separate, well-established procedure |
Qualitative overview, As of: July 2026. The individual quote and the respective current regulations of the federal government, canton and municipality are decisive.
The conclusion is unspectacular, and that is the actual message: the new build has the more favourable prerequisites, retrofitting the well-established procedure. It only becomes expensive when decisions are halved – the roof renovated without a system, the new build without empty conduits, the system «sometime».
The cheapest systems we build are on new buildings – the construction site provides scaffolding and electrician right away. The most complex ones are also on new buildings: on those that were handed over a few years ago without preparation. Then we look for cable routes through a finished house, and in the plant room, the one space that would have been needed is already occupied. For our projects in the region, the most valuable sentence to builders is therefore not «build the system immediately», but: make a decision – and if it is to be «later», prepare for it.
Frequently asked questions
Is retrofitting still worthwhile at all?
In most cases, yes – the guideline values of the market are retrofitting prices, and the one-off feed-in incentive (EIV) as well as tax deduction help out. Consumption, roof and tariff area are decisive, not the year of construction; you can find the classification under Is a solar system worthwhile?
Do I have to build more than the mandatory minimum in a new build?
You do not have to – but the requirement is intended as a lower limit. The step from the minimum to a sensible size is cheaper in a new build than it will ever be again, because scaffolding, crane and electrician are already factored in. Dimension according to roof and consumption, not according to paragraphs.
Is in-roof only possible in a new build?
No – in-roof is also a real option during roof renovation, because the roof covering is replaced anyway. Only as a pure retrofit on an intact roof does the change of construction method rarely pay off.
What does solar preparation cost in a new build?
Little in relation to the benefit: empty conduits, space reserves in the distribution board and load-bearing roof planning are small items during the structural work. Explicitly demand the preparation in the construction project – retrospectively, each of these points becomes a separate construction site.
I already have a system – do the new build arguments also apply to an expansion?
Partially: even with the expansion of an existing system, fixed costs dominate – scaffolding, travel, electrical work. Therefore, the same rule of thumb applies: expand properly or not at all, and take advantage of opportunities such as an inverter replacement.
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Both are our everyday business. We will tell you what your situation costs – and for new builds, also which preparation is worthwhile if the system comes later. Without obligation and concrete.
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Swissolar-certified specialist company · ESTI installation authorisation (Art. 14 NIV) · in Zurich since 2017 · over 150 systems completed · a personal answer from the specialist company, no call centre
Sources: Swiss Federal Office of Energy SFOE (Electricity Act/Mantelerlass), Canton of Zurich (Energy Act), Pronovo AG, Swissolar.
Last updated: 9 July 2026 · Author: ecoEn editorial team
