Thinking of buying a new microgeneration technology such as a solar panel: PV or thermal? Or some other technology such as a heat pump or a wood stove?
Ideally the consumer needs to ask their potential suppliers of green technology these questions – and get standard answers.
Financial Metrics Itemised
- £. Capital costs. What it costs to install and commission the solar panel etc.
- £. Yearly average net income = (savings + subsidy) – (operation + maintenance)
- Multiple X. Return on investment over warranted life / expected life
Energy Metrics When Operating
- kWh. Annual Energy budget: Gross – Parasitics = Net Energy
- Ratio. Typical Coefficient of Performance = CoP = Net Energy / Parasitics.
- EST Energy Rating. CoP should inform the EST’s ABCDEF energy efficiency rating.
Wider Life Cycle Analysis Metrics
- Years. How long to embodied energy payback?
- Years. How long to embodied carbon payback?
But how many of these metrics can you actually get from the microgeneration industry today?
Solar Twin Ltd have campaigning for 12 years greater transparency so that customers of microgeneration systems such as PV and thermal solar panels can make better choices.
We are not popular for having done so. We have even been ordered by a rogue trade body to stop doing so!
Please don’t let vested interests keep you in the dark. You have a right, as a consumer to be properly informed on questions like these.
Ask, ask and ask again!
Visible technology options for solar thermal consumers need broadening.
Here is a case study in the solar thermal arena.
Options for consumers need to be spelt out in a far more balanced way by government, trade bodies, regulators and bodies such as BPEC, CT, BRE, EST. Here are just a few suggestions which, if adopted, may help to deliver better balance. There are many areas to consider, including
1/ plumbing
2/ collectors
3/ circulation
4/ concept, operation & control
The next section looks closer at possible new agendas for these four areas.
1/ Traditional Plumbing Agenda
- Indirect twin series cylinders
- Indirect twin coil cylinders
- (gap)
- (gap)
- (gap)
The New Wider Solar Water Heating Plumbing Agenda Includes
- Indirect twin series cylinders (with shunt pump)
- Indirect twin coil cylinders (with shunt pump)
- Indirect heat to base cylinders (retrofits or replacements)
- Direct heat to base cylinders (retrofits or replacements)
- Thermal stores (prefeeding combis / high pressure plumbing)
All options need to be illustrated, explained fairly, and listed as suitable.
Exclusion can limit consumer awareness and choice.
Exclusion may even imply disapproval.
2/ Traditional agenda, solar thermal collectors can be:
- unglazed collectors
- evacuated tubes
- metal flat plates
- (gaps)
New wider agenda for solar thermal collectors includes:
- unglazed collectors
- evacuated tubes
- metal flat plates
- freeze tolerant flat plates (Solartwin)
- maybe also concentrating collectors?
Consider the pros and cons of not using antifreeze as a heat transfer fluid.
Also of using soft water instead. Drain down or freeze tolerant systems should be covered fully and fairly.
3/ Traditional solar water heating circulation agenda
- thermosyphon OR forced, and if forced, then
- on/off and high speed
- mains powered
New broader circulation agenda
- thermosyphon OR forced, and if forced, then
- on/off OR variable speed
- in low flow OR med flow OR high flow ranges
- mains OR PV powered
- low speed (using energy saving microbore pipes) and high speed (wasteful fat pipes)
Thermosyphon and PV pumping = zero carbon operation = delivery of free energy, free hot water, etc. Give quantitative clarity on: operational energy / carbon clawback / parasitics / coefficient of performance etc.
4/ Traditional Solar Thermal Conceptual / Operation / Maintenance Agenda
- Sealed, pressurised systems are the norm.
- Antifreeze is the norm.
- Indirect is the norm.
- Glass for glazing is the norm.
- Overheat control by “pump off” is the norm.
- Replacement cylinders are the norm.
- The Norm = The Best.
- Dismiss innovations as “not proven”.
- Installers must be high pressure G3 plumbers.
- Installers need mains electrics skills.
- Never discuss legionella.
- Don’t mention operating costs.
- Don’t mention maintenance costs.
- Nor coefficient of energy performance.
- Don’tmention / underplay carbon clawback.
- Don’t mention life cycle analysis.
- Focus on panel efficiency per square metre.
- Claim that solar fraction is a key number.
- Ignore this scope’s many exclusions.
- And tell consumers “what you need is…”
New Wider Conceptual / Operation / Maintenance Agenda
- Sealed & pressurised OR open vented
- Always filled OR drainback
- Antifreeze OR water OR air.
- Indirect OR direct.
- Glass OR polymer glazed.
- Overheat control by pump off OR heat export OR drain down.
- Replacement cylinders OR retrofits approaches
- Retrofits vary: internal Ht Exch / external Ht Exch / direct
- Be open to innovation and safety improvements.
- Recognise that the new might be the best.
- Installers don’t all need to be high pressure G3 plumbers.
- Installers don’t all need mains electrics skills.
- Discuss legionella safety, ranked in relation to plumbing options.
- State typical operating costs.
- State typical maintenance costs.
- Explain / state typical coefficient of energy performance.
- Explain / state typical carbon clawback.
- Explain / provide a typical life cycle analysis report.
- Debunk panel efficiency per square metre.
- Laugh that no backup heating = 100% solar fraction = cold showers!
- Focus on system (not component) performance.
- Explain how performance also matters beyond the panel.
- Explain why the net energy budget also matters.
- Target a reduction on bought in energy.
- Target a reduction in CO2 emissions.
Ask consumers what they want from this agenda.
Conclusion. It would be great for a trusted, independent and impartial organisation to be free to offer solar thermal consumers a far wider agenda than is traditional in UK.
UK consumers of microgeneration and renewable energy technologies would gain a more level playing field if a more balanced informational approach were to be adopted. The solar thermal industry want to think solar heating is technologically mature. In fact it is a diversifying into numerous techologies. The solar industry’s diehard metalheads want you to ignore, or better still for you to never even know the following facts:
- Several suppliers use water as a heat transfer fluid.
- There are around 5000 freeze tolerant collectors fitted in UK.
- Several suppliers offer open vented low pressure systems.
- Heat export is a standard option on many solar controllers.
- At least two leading UK made collectors use polymer glazing.
- Increasing numbers of suppliers offer PV pumps and controls.
- Increasing numbers of suppliers offer variable speed pumps.
- More suppliers than before are heating daily to the base of cylinders.
- Increasing numbers of suppliers use energy saving microbore pipes.
- Increasing numbers of suppliers offer heat exchanger retrofits.
- Some suppliers offer direct retrofits.
- Increasing numbers of suppliers offer thermal stores.
Customers deserve to be able to compare aspects such as: safety,
operational costs, maintenance costs, CO2 emissions, net energy savings,
and life cycle impacts within solar thermal technologies.
Today’s old solar thermal consumer-conning agenda is moribund – and a much wider agenda is now needed.
You heard it first from Solartwin!
