Thinking about having your own solar PV system for your building? Here are some Frequently Asked Questions
Solar photovoltaic or PV is the term used for the technology that convert the energy from the sun (directly or indirectly) into usable electrical energy. From the Greek word phos meaning light and volt from the Italian physicist, the renowned inventor of the electrical battery, Alessandro Volta. Interesting isn’t it?
The solar panels which are made up of smaller modules called cells are made from a special material, a semiconductor that moves electrons (electricity) with a small encouragement from the light energy from the sun. This electricity is direct current (DC) and must be converted to alternating current (AC) to be used in appliances in your house.
Once properly installed, the solar PV panels on your roof can last up to 25 to 30 years. With no moving parts, there is very little maintenance on your part other than the occasional wiping of dust which can be mostly taken care of by the rain. Handy.
Your solar PV system will keep converting away any energy it gets from the sun – even when it’s not shining directly on it. We call that daylight energy. The excess energy that are not used immediately are exported to the national grid where you get your conventional electricity from for about €0.19 per kWh. Currently in Ireland, unlike other countries, you’re not getting any money in exchange. This is called Feed-in tariff (FIT).
So unless you stay at home during the day, to use your kettle multiple times a day, the energy is only being used by your ‘always on’ appliances such as your fridge, etc.
The energy consumption case in buildings such as offices is even stronger simply due to the fact that we leave our homes to work in these buildings and we make our tea & coffee there. This is where a sizeable solar PV system can really be taken advantage of. Most commercial buildings can use all if not most of its energy generated on demand instead of paying an electricity supplier for it.
Since the electricity from the sun through the solar panels must be used as it’s generated, an electrical load (an appliance) must consume the electricity or it goes back to the grid. But you can keep more power for yourself if you have a battery. No, not the double A kind, a much larger battery to store the energy so that you can use that later on when you come home. Less export to the grid.
In today’s prices, not as much as they used to be. In fact, the cost is reduced to the point that it makes economic sense to get one with your solar PV system. You can learn more about battery storage here.
As a matter of fact, yes you can. It is another form of energy storage but not electricity. How about heating your immersion tank and keeping it hot during the day? Most houses have immersion heaters, why not use renewable energy to keep it topped up?
Why is that a good idea?
Well, to heat an immersion tank (120 litres) will take 2.5 hours from a cold start. Wouldn’t you want a hot shower when you come home without having to wait? Up to which point, you probably won’t bother then.
Ok, true but it’ll cost you €1.30 a day. Ah sure but that’s nothing. Really? That’s €475.00 per year. After 5 years, when your system has paid itself back, that can be a handy holiday pocket money or pay for your kids’ books!
By using these nifty devices called solar diverters also known as PV optimisers. Instead of exporting your excess energy to the grid which you get no money from, during the day, you can keep your immersion heated. But this leads to a sensible question…
A very good question to which there is a good answer. Your appliances in your home do indeed have electrical power ratings in order to work as per their design. Too much or too little power and they simply will not work, it might even break them. Your immersion heater however, is a heating element meaning it’s a resistive load. Whether your excess is 70W or 1kW, the electricity is there to convert it to heat energy. Some diverters are even smart enough not to call on grid power to supplement the electricity required to meet the 3kW immersion heater rating. Clever isn’t it? For more info about diverters, it’s here.
We can install these solar diverters with your new or existing solar PV system.
That’s all well and good but…
What your asking is the payback period of the solar PV system. The economics is simple enough, the electricity you don’t buy from a supplier goes toward paying off your solar panels. Typically, this is 5 to 6 years, if you’re smart about your usage, even less.
But come here, rumour has it that by the end of this summer, the Government will be offering grants to homeowners for installing solar PV panels on their roofs. However, SEAI registered installers must be the ones to put the panels up for you. Lucky for you, we’re registered and qualified! So, at the end of the day, that’s even less capital from you, quicker payback period and after that, profit! Happy days!