When you’re investing £8,000–£30,000 in a solar PV and battery storage system, it’s natural to compare prices.
The problem?
Many homeowners compare only the bottom line, not what they’re actually getting.
Many installers can produce a quote that looks remarkably similar on paper, but the specification, workmanship and long-term performance can be worlds apart.
At Bright Spark Energy, we’ve been called in to rectify numerous poorly installed systems across Sussex, Hampshire, Surrey and Kent. Almost every customer says the same thing:
“We wish we’d known this before choosing the cheapest quote.”
As the old saying goes:
Buy cheap. Buy twice.
When it comes to solar PV, battery storage and renewable energy, it couldn’t be more true.
Why can solar quotes vary by thousands of pounds?
Two quotations may both include:
- 16 solar PV panels
- 10kWh battery
- 5kW inverter
- MCS certification
- DNO application
Yet one quote could be £3,000–£5,000 cheaper.
How?
Because there are dozens of ways to reduce costs that most homeowners never see.
The cheapest quote isn’t always dishonest – it may simply omit features or use lower-cost products – but understanding those differences is essential before making a decision.
1. Undersized battery storage
One of the biggest ways installers reduce costs is by fitting the smallest battery possible.
It looks attractive on paper.
Unfortunately, it rarely delivers the savings customers expect.
A battery that is too small will:
- Fill by lunchtime in summer
- Export excess electricity for a low payment
- Empty quickly overnight
- Force you to buy expensive electricity back from the grid
A correctly designed battery should be based on:
- Household electricity consumption
- Overnight usage
- Heat pumps
- Electric vehicles
- Air conditioning
- Swimming pools
- Future energy demands
- Off-peak charging opportunities
A quality installer designs around your lifestyle, not a standard package.
2. Cheap batteries can become expensive
Battery technology is advancing rapidly.
While many low-cost batteries appear similar, there can be significant differences in:
- Cycle life
- Power output
- Software
- Warranty support
- Expandability
- Backup capability
- Intelligent energy management
Premium systems such as Sigenergy and Tesla Powerwall 3 provide:
- Whole home backup
- Fast changeover during power cuts
- Modular expansion
- AI energy optimisation
- Smart tariff integration
- EV charger integration
- Heat pump integration
- Continuous firmware improvements
Many cheaper batteries cannot.
3. Cheap solar panels often cost more over time
Not all solar panels are manufactured to the same standard.
While efficiency differences may appear small, quality differences become significant over 25 to 30 years.
Premium manufacturers invest heavily in:
- Quality control
- Long-term testing
- Financial stability
- Product development
- UK technical support
Unknown manufacturers may disappear completely.
If they leave the market, warranty claims can become extremely difficult.
Saving £500 today may cost thousands later.
4. Unknown brands mean unknown risks
One growing concern in the UK solar market is orphan products.
We’ve already seen manufacturers withdraw from the UK, leaving customers without:
- Spare parts
- Technical support
- Firmware updates
- Monitoring apps
- Warranty assistance
Before accepting a quotation, ask:
- Is this a recognised manufacturer?
- Do they have UK support?
- How long have they been operating?
- Will replacement parts still be available in ten years?
5. No panel optimisers
Optimisers are often removed to reduce costs.
Unfortunately, removing them can reduce long-term system performance.
Systems using SolarEdge optimisers or Enphase microinverters provide:
- Individual panel monitoring
- Better performance during partial shading
- Greater energy generation
- Easier fault finding
- Enhanced fire safety
- Future expansion flexibility
Even a small amount of shade from:
- Chimneys
- Trees
- Satellite dishes
- Roof windows
can significantly affect a conventional string system.
Optimisation protects your investment. We’ve written more about this in can you install solar panels on a shaded roof?
6. Poor cable routing
Good cable management takes time.
Time costs money.
Budget installations often include:
- Surface-mounted conduit
- Exposed trunking
- Untidy external cables
- Visible roof cabling
- Poorly planned inverter locations
Professional installers carefully plan cable routes before installation begins.
The difference is immediately obvious.
7. Poor roof workmanship
Solar should protect your roof – not damage it.
Unfortunately we regularly inspect systems suffering from:
- Broken roof tiles
- Incorrect flashing
- Poorly fitted mounting hooks
- Damaged membranes
- Water ingress
- Loose roof fixings
Roof repairs frequently cost more than the original saving achieved by accepting the cheapest quotation.
8. Inferior mounting systems
The mounting system supports your entire investment.
Quality systems undergo extensive testing for:
- Wind loading
- Snow loading
- Corrosion resistance
- Structural performance
- Long-term durability
Choosing recognised manufacturers ensures long-term reliability.
9. Little or no system design
Many low-cost installers produce quotations using satellite imagery alone.
Professional system design should include:
- Roof measurements
- Shading analysis
- String calculations
- Electrical design
- Voltage drop calculations
- Structural assessment where appropriate
- DNO compliance
- Fire safety considerations
- Future expansion planning
Design is one of the most valuable parts of your investment.
10. No structural assessment
Not every roof requires a structural survey.
However many do.
Especially:
- Older properties
- Listed buildings
- Slate roofs
- Clay tile roofs
- Large installations
- Commercial buildings
Ignoring structural considerations may save money initially but create significant problems later.
11. Poor electrical workmanship
A professional solar PV installation should comply with:
- BS7671
- MCS standards
- Building Regulations
- DNO requirements
- Manufacturer instructions
We regularly encounter installations with:
- Poor cable management
- Incorrect protective devices
- Missing surge protection
- Incorrect earthing
- Poor labelling
- Inadequate isolation
- Untidy consumer units
These are not simply cosmetic issues.
They affect safety, reliability and future maintenance.
12. Fire safety isn’t optional
Modern solar PV design should include fire safety from the outset.
Quality installers consider:
- Safe cable routing
- DC voltage reduction
- Rapid shutdown
- Optimisers or microinverters
- Emergency isolation
- Fire service access
- RC62 guidance
- RC67 recommendations
These measures protect homeowners, occupants and emergency services.
13. Disappearing solar companies
Perhaps the biggest hidden cost is choosing an installer that no longer exists.
The renewable energy industry has seen hundreds of companies disappear over the past decade.
When they do, customers are often left without:
- Workmanship warranty
- Technical support
- Annual servicing
- System monitoring
- Future upgrades
Always ask:
- How long has the business been trading?
- Do they employ their own engineers?
- Do they provide ongoing servicing?
- Are they financially stable?
- Can they provide recent references?
Buying from a company that intends to support you for decades is invaluable.
14. The cheapest quote rarely delivers the best value
The best solar PV systems are:
- Correctly designed
- Properly installed
- Built using premium components
- Supported by experienced engineers
- Expandable in the future
- Installed by companies that will still be here years later
That combination almost always produces the lowest cost of ownership.
Questions every homeowner should ask before choosing a solar installer
Before accepting any quotation ask:
- Is the battery correctly sized?
- What happens during a power cut?
- Are optimisers included?
- Which mounting system will be used?
- How will the cables be routed?
- Which panels are being installed?
- What fire safety measures are included?
- Can I expand the system later?
- Do you provide servicing?
- Who do I call in five years?
If the answers are unclear, think carefully before proceeding.
Why Bright Spark Energy?
At Bright Spark Energy we don’t compete to be the cheapest.
We compete to deliver the best long-term value.
Every installation is individually designed around your property, your electricity usage and your future plans.
We specify products we would happily install on our own homes, including:
- Sigenergy
- Tesla Powerwall
- SolarEdge
- Enphase
Our systems are designed with:
- Future expansion
- Whole-home backup
- Electrical safety
- Fire safety
- Neat cable routing
- Long-term reliability
As a local installer covering Sussex, Hampshire, Surrey and Kent, our reputation depends on every installation performing for decades – not just until the final invoice is paid.
Buy cheap. Buy twice.
A solar PV system should last 25–30 years.
Saving a small amount today can easily cost many thousands over the lifetime of the system.
Choose quality.
Choose experience.
Choose products that will still be supported years from now.
Because the cheapest quote is rarely the cheapest system. If you’d like a quote you can actually compare, get in touch.
Frequently asked questions
Why are some solar quotes much cheaper?
Lower-cost quotations often reduce specification by fitting smaller batteries, lower-quality equipment, omitting optimisers or reducing installation time.
Are premium solar panels worth it?
Yes. Premium manufacturers typically provide better long-term reliability, stronger warranties and lower degradation over time.
Why should I choose a local solar installer?
A reputable local installer is easier to contact for servicing, warranty support, future upgrades and ongoing maintenance.
Can I add more batteries later?
Some modular systems, including Sigenergy, allow future expansion. Others have limited upgrade options.
Is the cheapest quote ever the best value?
Usually not. A professionally designed, well-installed system using quality components almost always provides the best long-term return on investment.
