Ready to generate your own electricity?

Apart from kW size, detailing and cost-saving potential, ask plenty of material questions during the site visit by your SEAI-registered PV engineer. Is the roof suited to PV and what quality of no-lift fixing does the firm use? What warranty can you expect? Could the array be placed (as here) on a garage or outbuilding?

Kya deLongchamps starts her journey toward mirco-generation with photovoltaic solar panels that can produce free, green electricity.

I've made the commitment to photovoltaic panels for my house. Utilising semiconductor materials that react to solar radiation to create electricity, photovoltaic (PV) panels and optional storage batteries are now State grant-aided through the Sustainable Energy Authority of Ireland. I’m sceptical about anything new when it comes to a major spend — even a lean, green spend with a virtuous aftertaste. Just what are the incentives, projected cost, and the hassle of producing at least a portion of your own current?

System costs

The following are the figures for PV from Electric Ireland. This system, like other systems I’ve investigated thus far, is installed in a day and includes the panels, the inverter (to transform DC to AC current), and software to monitor generation in real time.

A 1.8kW array of six panels installed over two areas of a roof will come in at €4,800 including VAT and installation. An additional .3Kw panel can lift that daylight collection potential to a 2.1kW set of seven panels. This will add just €300 before grant aid with an actual final cost of about €150. Adding a diverter would add €400 to direct surplus energy during the daylight hours to the hot water supply.

The presence of a storage battery would make a diverter unnecessary according to an Electric Ireland representative I spoke to, but Martin Desmond, CEO of PvGen (pvgeneration.ie), tells me that the diverter should retain its role providing hot water from surplus collection during the day.

The battery from Electric Ireland was the number that gave me pause — €6,900 for a 5kW Sonnen unit including VAT and installed. So all in and before grant aid or the final confirmation of these figures after my engineer’s visit, I will be looking at a choice of (before SEAI aid):

  • €4,800 for a 1.8kW array working alone
  • €5,200 for a 1.8kW array plus a diverter for hot water during the day
  • €5,500 for a larger 2.1kW array plus a diverter
  • Around €11,000-€11,500 for a 2.1kW array matched to a 5kW battery (without supplied diverter)

SEAI grant aid comes in at €1,260-€2,400 depending on my choices. To get the SEAI battery grant of €1,000, you must install the battery at the same time as the array. Install a battery, and the kWh panel grant increases by €700 per kW, up to 4kW (otherwise it’s 2kW or €1,400). The total grant aid possible through the SEAI is €3,800. That juicy Home Renovation Incentive Scheme claw-back of VAT? Flattened in the last budget.

So the final finish delivers a cost of €3,540 to €8,800 for a working PV array after SEAI grant aid being awarded. That’s a lot to think about even with the interest-free payment package over 36 months channelled through an Electric Ireland account. The minimum deposit is €960, which climbs depending on the package.

I had a second quote by phone for a very similar product to the €5,500 Electric Ireland offering that was €912.75 more for a 2kW array with diverter at a rounded €6,412. This more expensive deal also shaved .1kW of working panel size off the system. Comparing like with like, is not easy with different specifications on different products.

For larger arrays, PV Generation in Cork (pvgeneration.ie) offers a generous 4kWp of PV with 6.3kWh lithium ion battery storage which comes in at less than €10k after SEAI grant aid.

Savings and payback

Now, this is a difficult area to drill down on. The weather is impossible to closely predict (ask Met Éireann) and the habits and lifestyle of the users of the PV array and any battery or diverter will influence just how long this large capital outlet and ongoing kW unit savings will come home in a meaningful way.

If you are at home all day, and able to run your large appliances sequentially (not together) during daylight hours, obviously the return will be faster as you generate that power in real time. Using a battery and NightSaver electricity rates could again coax the savings.

  • Electric Ireland offers the following guide for a 1.8kWh panel without a battery:

  • Kildare: 1,520 kWh (Savings: €239)
  • Clonmel: 1,480kWh (Savings: €232)
  • Cork: 1,610 kWh (Savings: €253)

Based on 85% consumption at 18.5c per kWh, that’s a saving a click over 38% of the average household kWh use in Cork.

With those modest savings, and clattering it out on a calculator, I would pay for my cheapest array in savings in about 14 years. It’s hard to get excited about that, but keep in mind that energy prices are rising and in 10 years a kWh of energy is unlikely to be 18.5c. What about a heat pump or an electric car? There’s a lot of play there.

For a 2kW size of array without a battery, I was told my another Cork supplier by phone that the savings would be in the area of €360-€400 per year, which seemed initially wildly out of sync with the SEAI’s projected savings. The same supplier advised me that a battery for a 2kW size array of their eight panels was “overkill” and suggested an array/diverter package would be sufficient.

I know you all love online calculators, so here’s one from the SEAI which includes more individual detail, but don’t treat this as a site survey: www.seai.ie/resources/tools/solar-electricity-calculator. Plumbing in my own situation, including the orientation of my roof, the size of a proposed array (2k/2.2W in my case) plus the crucial question of how much of the day I was at home, my figures came back at €335pa in savings, or a 12-year payback — so a bit better than the standard savings cited by the SEAI which are clearly taking in all roof aspects and all times of use including homeowners absent at work from 8am-5pm.

Adding a battery will increase your potential savings, and depending on who you talk to, this could be as much as 70%-80% off your current kWh unit usage from the grid. I’m told my 4.2kW array (with a 6.5kW battery) should comfortably net €1,000 in savings. Standing charges and VAT will change little however, so don’t presume your actual bill will fall by 70%-80%. Without a battery, PV is a use-it-or-lose-it experience, gifting surplus energy not used by the diverter back to the national grid.

The amount of power you can generate and use in your home from PV during daylight hours depends on the weather, the orientation and pitch of the panels, any shading and (obviously) the number of panels making up your roof-mounted system and the presence of any battery. We’re not talking about 100% capacity and the kW given for the panels is peak wattage or max capacity — rarely a go. Add a battery and it’s tempting to think you’re an independent micro-generator and can scoff at any incoming electricity bill.

In conversation with Brian Denvir, solar PV coordinator for the SEAI, I was struck by something he said regarding a claim of 80% savings for an array with a battery from a supplier I had interviewed.

“This example,” Brian explained, “would be for a home with below-average electricity consumption. A 3kWp system will generate around 2,600kWh of electricity per annum. Therefore, if the home’s average annual electricity demand is only 3,250kWh, then yes, this could reduce their grid electricity consumption by up to 80%, assuming that the battery allows them to use 100% of the electricity they generate.”

For more information and a register of approved PV suppliers/installers, go to seai.ie

Going for green gas

Bio liquefied petroleum gas (BioLPG) is the latest product from Calor Gas to address the greenhouse emissions levelled at fossil fuels with a carbon value 80% lower than oil and gas alternatives. BioLPG (100% or a blend, depending on supplier) is produced at the Neste biodiesel refinery in Rotterdam, a byproduct of hydrotreated vegetable oils (HVO) diesel production, and is fully traceable through the Sustainability and Carbon Certification Scheme, and certified as renewable (not carbon neutral).

Suited for use for heating and cooking, bulk tanks, and patio gas cylinders, bio liquefied petroleum gas does not carry a carbon tax and therefore the complete product is comparable to standard LPG in pricing and will work with your existing LPG (tank-fed) boiler and appropriate LPG appliances.

With thanks to Mary Coughlan, LNG Project Manager, Calor. For further information, phone 1850 812450 or visit calorgas.ie

  • Brightest and best

  • Choose the right size and detailing of system for your household usage from the start. It’s cheaper to get it right first time than to “add on” as you go
  • Future-proof: Would you think about an electric (EV) car or a heat pump for heating in the coming years? Will your system be ready?
  • Follow your power usage with the app tuned to your device. There’s an app with most batteries, free through the maker’s website, if you want to opt out of any charged service
  • Install an instant hot-water tap and ditch that expensive, watt-hungry kettle
  • Use timers for appliances that can be safely on during the day, when you are not at home. Do not include the tumble dryer, which is safer to run when you are at home
  • Run appliances, including the washing machine and dishwasher, sequentially, to use power generated by the PV, intelligently, in real time
  • Even if you don’t vouch for a PV battery, choose battery-operated (rechargeable) devices —strimmers, lawn-mowers, and the household vacuum to store and offset the surplus bleed back to the national grid of unused power
  • Investigate new forms of electric heating
  • Reduce your power usage, as much as possible, with efficient behaviour

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