TLDR: They both have advantages or disadvantages, crucially though, the complexity of the decision-making means that without serious research and upskilling the homeowner will have to make a leap of faith and take a risk. Unless, of course, they consult an Independent Chartered Engineer to cut through the confusion and act as their personal champion.

My aim here is to share insights gleaned from my years in the field, underpinned by the findings of my doctoral research, to help you make a more informed decision. This is an in-depth read for people serious about installing solar and batteries (or an ASHP).

Hi, I'm Dr. John Rowlatt and I am a Chartered Building Services Engineer who is licenced by CIBSE, I am now in my third decade of working with homeowners and energy. I've spent more than a decade specifically designing, surveying, and advising on renewable energy systems for homes. Please visit Homeenergy.doctor for a copy of my qualifications, and you will see it's an area that I am both experienced in, and passionate about. Over the last several years I have studied for and completed an MSc and then a PhD in Energy & Sustainable Development at De Montfort University, where I have dived deeply into how homeowners engage with the prospect of energy efficiency retrofits. The journey to a solar-powered home, likely with battery storage, can certainly be an exciting one that promises lower bills and a smaller carbon footprint in addition to greater home comfort and an improved lifestyle. However, it's also a significant investment, and one of the very first, and most crucial, decisions you'll face is selecting the right installer to talk to. Will it be to choose a large national company or a local installer. So, which is better and who do you talk to?

What My Research Uncovered: The Homeowner's Reality

My PhD, titled "Engaging the Outright Owner-Occupier (Rotarian) towards a Net Zero future - attitudes, motivations, barriers and misconceptions of energy efficiency retrofit," resulted in a thesis (download here) which highlights data and results from hundreds of detailed surveys and interviews. It confirmed many of the anecdotal challenges I’ve seen homeowners grapple with and provided some stark data. Several findings are particularly pertinent when considering who to entrust with your renewable energy installation:

●     A Prevailing Distrust: A key takeaway was a significant lack of trust among homeowners towards both governmental advice and, crucially, local installers (SMEs) when it comes to energy efficiency information. The abstract of my thesis notes that "neither the government nor Small to Medium Enterprises (SMEs) were trusted messengers". This is a fundamental hurdle, as most local installers are SMEs. Significantly, however, National installers ranked even worse in terms of trust when this question was directly addressed with interview participants.

●     Low Technical Confidence: My research found that "only 23% of those surveyed felt they had the practical ability to enact a new energy efficiency project in their home". This isn't surprising given the technical nature of these systems, but it highlights a vulnerability when assessing complex quotes and designs. Effectively, the homeowner is not qualified to judge properly and they recognise this.

●     The "Value for Money" Conundrum: The "issue of getting value for money using loomed large in the home-owner's mind,". To be clear, this isn't just about the cheapest price, but about the overall worth and reliability of the investment. There have been recent programs such as Solar Together schemes and subsequent negative reports where this problem has been highlighted repeatedly – that a (supposedly) low price does not equate to value nor ensure quality. In fact these schemes have been described by some as “a race to the bottom in terms of quality”.

●     The Quest for Trusted Messengers: There's an undeniable demand for "better information provision" and "suitable trusted messengers" that homeowners feel they can genuinely connect with and rely upon. My work indicated that independent professionals who are not being paid to sell a product nor promote a company are seen as very influential and the most trusted option by homeowners.

●     Complex Decision Dynamics: Energy upgrade decisions are rarely made in isolation. My thesis found that "two thirds of energy efficiency upgrade decisions are either made jointly (63.3%) as a male and female couple, around one in ten (11.4%) by solely by women and only a quarter (25.3%) solely by men," this statement challenges traditional assumptions about who makes home renovation choices. Making sure that all sides are represented in terms of desires and system suitability really matters – is everyone getting what they want?

●     Age and its influence: Finally, age often influences perception on payback periods, value and the willingness to accept perceived risks. There is not enough information provided showing that the installation of renewable technologies can significantly increase both the desirability and the value of the home. Often meaning this is and investment not a purchase. There are medically researched physical influences on the decision-making ability and the affect of age on risk perception. These often lead to a lack of good research by the homeowner and a reduction in the ability to process results in a useful manner. Furthermore, this often leads to misconceptions causing them to miss out on the personal and comfort benefits that would have accrued from the installation of a renewable energy system.

In combination it presents a complicated landscape where the homeowner can be under-informed and feel out of their depth, resulting in a cautious approach which leaves then searching for trusted guidance. Recognising this is important in order to ensure you are getting suitable support when considering installer options.

National Giants vs. Local Experts: A Closer Look

The decision isn't black and white. Both national companies and local installers come with a set of potential advantages and disadvantages, however, a key note is that many National Installer subcontract their work out to local regional installers in order to have the coverage they require. Effectively meaning that you may end up with the same installer no matter what, just with different pricing and design or support standards.

Local Installers (Often SMEs):

●     Potential Advantages:

○     Personalised Service & Accountability: Local firms often provide a more direct and personal point of contact, due to a smaller internal hierarchy you can often, if needed, talk to the key decision makers themselves like the Operations Director or the business owner. This can foster a stronger sense of accountability and build trust – a direct antidote to the general distrust my research highlighted. Reputable local installers understand that their business thrives on positive local sentiment.

○     Strong Local Reputation & Knowledge: Their success is intrinsically linked to their standing in the community. A good local reputation, built over years of quality work, is invaluable. They are also typically well-versed in local planning regulations and the specific requirements of your local Distribution Network Operator (DNO) regarding what can be connected without issue. Furthermore, they can often upon request provide local references from previous clients that you may reach out to. Talking to previous clients and homeowners who have gone before you on the installation journey is greatly valued by those just starting on a home energy upgrade.

○     Tailored and Flexible Solutions: Smaller, independent installers can often be more flexible in designing a system that is perfectly tailored to your home's unique characteristics and your specific energy needs, rather than a one-size-fits-all approach. This matters because when you are considering the vagaries of roof types, sizes and construction then a few inches difference in size makes all the difference as to what you can fit. Most National Installers have standardised larger tolerances that they adhere to as guidelines due to the fact they are often not in control of the survey and installer phase and have never actually seen the roof they are quoting you for. This often means that what a local installer can/will fit to a roof may be significantly larger than a National Installer. They should all conform to the MCS standards and installation guidelines – there is no worry there – in practice it is the difference in tolerances that a company chooses to specify which is a consequence of you talk to a salesperson on a phone or an experienced on-site surveyor.

○     Potential for Lower Costs: With generally lower overheads than national companies (e.g., smaller marketing budgets, less complex management structures, not having wider shareholders), local installers can sometimes offer more competitive pricing, directly addressing that "value for money" concern. It is very rare, and I mean very, to see a National Installer be cheaper or even the same price as a local installer.

○     Supporting the Local Economy: For many, this is a significant and positive factor, keeping investment within the community. Helping build skills, jobs and education for local people will help build long term resilience and the after sales skills you will need later in the life of the system to maintain and service it or any upgrades you may require.

●     Potential Disadvantages (Local SMEs):

○     Resource Limitations: Smaller businesses might face constraints in terms of manpower or equipment, which could impact project timelines, especially during busy periods. My thesis noted the construction sector, which includes these installers, is largely composed of micro-SMEs, effectively meaning that there can be a sub-contractor supply chain even with small companies.  It is important to check if the installation crews are actually employed by the installer or is there another link in the installation chain in case of complications.

○     Variability in Expertise and Quality: While many local installers are highly skilled and accredited (all will be MCS certified for example) this is no surety of delivered expertise. Yes, they should be competent but, for example, do they grind out the back of the tiles (as appropriate) to flush in the hooks to the roof to ensure it remains watertight? Are they specifying appropriate hardware based on the location they are recommending to install into? What about thermal management? What difference does this make to the homeowner? Without having industry technical knowledge, it's hard for a homeowner (like the 77% in my study who felt they lacked practical ability) to rigorously assess this or even understand there are nuances to know, nor what they should be checking for. The truth is that the installer will most likely know the answers and the best practice for all things but it can be hard for the consumer to ensure they get it. This comment certainly also applies to National Installers.

○     Product Range and Financing Options: They may have access to a more limited range of product brands compared to national players, and perhaps fewer established partnerships for financing options. In practice the business owner will most likely have a preferred product brand and range that they like working with for varying reasons. They should, however, be able to offer different products that may be more suited to certain types of installations or locations for hardware layout. If they do not then this may be a red flag. In terms of finance, any finance that is offered has to be paid for by someone and that will be the end user – you. Yes, they may not offer finance compared to say a National Installer, however 5 minutes with a calculator and the comparative quotes may allow you to judge whether installer finance seems sensible compared to just going to regular loans companies if so desired.

○     Business Longevity and Warranty Support: The long-term viability of a smaller business can be a concern for warranties. In practice, however, the company is often only providing a limited term warranty for their installation quality – typically maybe 5 years. The products themselves come with their own warranties. It is important to read the product warranties as they often only cover the replacement of the parts but not the cost to re-install the new parts – you may be liable for that cost if it is not specifically covered by the installer in their terms.  Insurance Backed Guarantees (IBGs) have previously long been touted as beneficial and indeed crucial, however, recent research shows they rarely pay our, with one of the largest providers having not paid out one claim in over a year as noted in the PhD thesis. As such the MCS have removed the requirement for installers to issue the insurance. Consumer advice bodies like Which? often highlight the importance of checking warranty terms and installer stability and liability.

○     Overcoming the Trust Deficit: Given the general scepticism towards SMEs found in my research, even the best local installers may need to work harder to build that initial trust.

National Installers:

●     Potential Advantages:

○     Brand Recognition and Perceived Stability: A well-known national brand can offer an initial sense of security and the perception of long-term stability. In reality, this may not actually be an advantage to the consumer but rather to the National Installer. However, it can bring some sense of comfort at the initial stage of interest.

○     Standardised Processes: Often have well-defined sales, installation, and customer service protocols, which can lead to a consistent (though not necessarily superior) experience. This clearer governance process should mean that there is absolute clarity of what is being offered and what benefits should be received. It does not, however, mean that they will be able to act flexibly in a tailored and bespoke manner to you as you are one of thousands that they service each month.

○     Comprehensive Financing Options: Typically, have established relationships with finance providers, offering a broader array of payment plans, leases and terms. Please note that all finance options have a cost and you will bear them somewhere in the final price paid.

○     Extensive Product Choice & Availability: Their larger purchasing power can mean access to a wider variety of products and potentially better stock availability. In reality this is often the very opposite, trying to leverage bulk buying and procurement strategies for their best margin means they will often only offer a very limited range. Maybe one panel brand, one inverter and battery brand with any outliers such as a Tesla Powerwall as an option. They will often have stock as standard but don’t expect a good choice – standardisation is the key principle for large companies.

●     Potential Disadvantages:

○     Higher Overall Costs: Significant marketing budgets, extensive management structures, and shareholder expectations can translate into higher prices for the homeowner. This, combined with longer installer sub-contractor chains in many cases will add to costs. They may be competitive on one aspect, e.g. battery pricing but the core product (solar) may be where their overheads are buried – comparison is needed. Often accessories, add-ons and optional extras are where they make a margin – be aware.

○     The Subcontractor Layer: This is a critical point. National companies very frequently subcontract the actual installation work to local SMEs. If this is the case, you may be paying a premium for the national brand, yet the hands-on work is done by a local SME, potentially reintroducing all the variables and trust concerns associated with them. In many cases, when you are talking to one of the larger local SME installers already, they may actually be one and the same in practice as they act as a local installer for the National Installer as well. This is genuinely common. Understanding this relationship and who is ultimately responsible for the quality of the installation and aftercare is vital.

○     Impersonal Service: Dealing with a large organisation can sometimes mean a less personal experience, navigating call centres, and dealing with multiple points of contact. Often your ability to actually speak to your system designer or surveyor may be challenging.

○     Standardised, Less Flexible Solutions: There can be a tendency to promote standardised system packages that may not be perfectly optimised for the specific needs of your property or your energy consumption patterns. This contrasts with the need for solutions tailored to the UK's diverse housing stock, an issue touched upon in my research concerning retrofit challenges.

○     Sales-Driven Approach: Some national companies are known for employing more assertive sales tactics, which can be off-putting and may not align with a careful, considered decision-making process, especially for those who are naturally risk-averse. Consumer forums and review sites often feature discussions about such negative experiences.

My research strongly suggests that outright owner-occupiers, often being older, are generally more cautious, may feel disengaged from highly technical projects, and are understandably keen to ensure they receive good value and can trust the information they're given. This implies that regardless of choosing a local or national installer, the homeowner requires a robust way to verify credentials, objectively compare often complex quotations, and be confident that the proposed system is genuinely the right one for their needs and not just what the installer prefers to sell.

The Indispensable Role of an Independent Chartered Engineer Consultant

This is precisely where the expertise of an independent Chartered Energy Consultant becomes not just beneficial, but, in my view, essential for many homeowners. The challenges and needs identified in my doctoral research – the trust deficit, the information overload, the lack of technical confidence – are all areas where a qualified and truly independent advisor can provide profound value.

1.    Bridging the Trust Deficit – Your True Advocate:
My PhD clearly identified a lack of trust in SMEs and a corresponding need for "suitable trusted messengers". An independent consultant is uniquely positioned to be that messenger. As a Chartered Engineer, I am bound by a strict professional code of ethics and conduct set by the Engineering Council and my professional institution (CIBSE). My advice is impartial; my sole focus is your best interest, not a sales commission or promoting a specific brand. This independence is the bedrock of trust.

2.    Providing Clarity and Unbiased Information:
The call for "better information provision" was a strong theme in my research. Renewable energy systems are complex. A consultant demystifies the technical jargon, explains the differences between panel types, inverter technologies, battery chemistries, and how these translate into real-world performance in carrying locations and your ultimate savings. We can help you understand the often-confusing array of information and filter out the marketing noise. This directly counters the "information and ignorance" theme that emerged as a barrier in my research.

3.    Empowering You with Technical Expertise:
My research showed that only 23% of homeowners felt they had the practical ability to manage such projects. A Chartered Engineer consultant brings the necessary high-level technical expertise to the table. With suitable data we can:

a.    Conduct a thorough assessment of your property's suitability (roof orientation, shading, structural considerations, electrical systems).

b.    Accurately calculate your energy needs and design an optimally sized system.

c.     Critically evaluate the technical specifications and designs proposed by installers.

d.    Not ready for 3 quotes from installers yet? We can help you bridge that gap by supporting you to feel confident enough to go to the open market for quotes.

4.    Ensuring Genuine Value for Money:
The concern about "value for money using an SME" is a primary anxiety for homeowners. A consultant champions your financial interests by:

a.    Helping you understand what constitutes a fair and competitive price for the proposed system and installation.

b.    Scrutinising quotes in detail, ensuring you are comparing like-for-like and identifying any hidden costs or over-specifications.

c.     Advising on the long-term financial viability, including realistic payback periods and return on investment, taking into account your specific circumstances and energy usage. This addresses the concerns about age and investment horizons that my research highlighted.

d.    Helping you understand potential "rebound effects" where changes in behaviour post-installation might affect actual savings (therefore recommended system sizes) – an issue often overlooked but noted in government and academic literature on energy efficiency.

5.    Navigating the Complex Decision-Making Journey:
My thesis pointed out that decisions are often made jointly and that age can affect risk perception. A consultant acts as a neutral facilitator, providing clear, objective information to all decision-makers in the household. We can also help you understand contracts, warranty terms, and the responsibilities of each party, reducing the perceived risk. Finally providing a step-by-step guide of actions to take

6.    Removing the need for a Salesman:

At initial contact stage many companies will initially push you to a Salesman (person) whose job is effectively always to attempt to close the sale at some point. Many homeowners just do not want that perceived hassle. Almost all homes can be (and usually are) remotely surveyed by the salesperson or company before they send someone to site as that act incurs a cost to them. The Independent Chartered Engineer can do this same service remotely and design a system with a significant level of detail fully offsite. You will always need a pre-installation site survey and roof inspection which the company should do as a matter of course. However, you can remove the Salesman and their related commission as a cost incurred. In many cases in the renewables industry this can be up to a standard flat 10% of the total quote i.e. many £100s of pounds if not over £1,000. The Independent Chartered Engineer is very unlikely to cost you anywhere near in terms of cost. Allowing you to ask the company to provide you a quote minus its normal Salesman’s commission as you already know what you want and simply want a fitting price.   

7.    Overseeing Quality and Compliance:
While not typically managing the project day-to-day (unless specifically engaged to do so), a consultant can help you to ensure the installation adheres to the agreed design, relevant industry standards (like MCS, which is crucial for quality and consumer protection), and best practices.

The Significance of "Chartered Engineer" Status:

Achieving Chartered Engineer status is a rigorous process. It signifies that an engineer has demonstrated a high level of technical and professional competence, including a commitment to ethical practice, safety, and ongoing learning, as assessed by a licensed professional engineering institution. For you, the homeowner, this designation provides a significant mark of assurance that the individual advising you is a credible, accountable, and highly qualified expert in their field. The Engineering Council in the UK, for instance, sets and maintains the standards for the engineering profession. This status is arguably of much greater importance to you than an installer having a TrustMark or MCS accreditation as the licensing is much more rigorous.

Making Your Informed Choice: The Path Forward

The decision between a national or local installer for your solar and battery installation is multifaceted, with no single answer fitting every situation. Both avenues can lead to excellent outcomes if approached with due diligence and the right support. However, my research into the lived experiences, attitudes, and anxieties of homeowners strongly indicates that embarking on this journey without expert, impartial guidance can be fraught with uncertainty and potential pitfalls most likely leading to inaction. The prevalent distrust in direct sales channels, the acknowledged lack of technical confidence within the homeowner, and their deep-seated desire for genuine value are not to be underestimated.

Therefore, based on my extensive experience in the renewable energy sector and the compelling findings of my doctoral research, my recommendation is to consider engaging an Independent Chartered Engineer such as Homeenergy.doctor from the outset. Independent Engineers act as your advocate, your technical interpreter, and your trusted advisor. We are here to demystify the process, empower you with knowledge, ensure you are treated fairly, and guide you towards an optimal solution that truly meets your energy ambitions and financial realities. Do not forget that a truly integrated home energy system will, over time, likely include and air source heat pump.

Therefore, designing a system that takes this likelihood into account means a holistic approach – not just selling you something now... As such, since the Independent Chartered Engineer is not actively selling you hardware nor promoting a company directly, they should take this into account and provide best practice on being future proof and potentially modular in their design recommendations to allow for future expansion as indicated. This aligns perfectly with the required principles of trusted, professional guidance that my academic work has so clearly identified.

Investing in a renewable energy system for your home is a significant and commendable decision – well done you even for reading this. Ensuring that decision is built on a foundation of independent, expert advice is the surest way to guarantee it's a successful and rewarding one for many years to come.

Dr. John Rowlatt - Chartered Building Services Engineer, is a renewable energy systems designer, surveyor, and researcher with over a decade of experience in the field. His PhD from De Montfort University, "Engaging the Outright Owner-Occupier (Rotarian) towards a Net Zero future - attitudes, motivations, barriers and misconceptions of energy efficiency retrofit", provides key insights into homeowner decision-making.

If you are serious about buying solar - and I suspect you are otherwise why would you have read this far - the next sensible step is to book an appointment - ask questions about YOUR situation and get the benefit of a nuanced and bespoke response leveraging decades of knowledge.