About two weeks ago my eldest son asked a simple question "Dad - why don't we go solar?". Talk about an idea whose time had come. We weren't financed nicely when the solar wave first broke - and you could spend $24K for a 3kilo Watt system that guaranteed your a 0.66 cents feed in from the grid for every kilowatt hour (kWh) produced. It was an idea that has been at the back of my mind for some time now - but I had done no research on it. But having three teenagers our annual electricity bill is around $3,600. So I thought why not indeed?
I googled a bit and found the idiots guide to and how to get decent quotes and read Whirlpool's Green forum and came to a very interesting realisation - now's a great time. My research basically showed electricity costs have pretty much quintupled whist solar cost had gone down by a factor of three, whilst capability and energy management systems had pretty much arrived. This is the short story of how in two weeks we sized, selected and implemented a 4.94kW system that is monitors energy provision and you can browse the web any time to see how your house, or thousands of people all over the world are producing in real time.
The biggest learnings I got where
- There are a handful of tier one solar cells (Trina from China and Q-Cell from Germany) seem to be the best
- Inverter selection is critical - you feed all the solar panels arranged in identical rows (called strings) into one big, unintelligent inverter that will die in around 8 years or you go with intelligent, programmable micro-inverters that allow amazing flexibility but cost more
- You plan your system to cover your average Summer day time load (for me around 30 kWh)
- You consider a system that you can add battery storage to to better manage peak versus average day time load
- You reality check that you can consume at least 70% of the energy you produce rather than over produce and feed it to the grid for a pittance of a pay back rate.
- You select an energy monitor that displays not only what you produce but what you consume
- You seek to implement a solution with a four to six year payback over a likely twenty five year life (meaning it should save you tens of thousands of dollars)!
The first week was spend modelling how large a system we wanted, and coming to the realisation it should offset our minute by minute day time electricity consumption. So after reviewing a few quarters of energy bills I was able to reasonably determine how much we use each day. Next it was understand the tariff system - I am with AGL so it costs me 55 cents for peak power, 23 cents for shoulder and 11 cents for off peak. I can earn a measly 8 cents for power we feed into the grid - even at peak times! This means you size your average hourly peak load, then double it to allow for semi-sunny days.
I did all this and arrived at 5 kW - which every quote I got confirmed my analysis. But the biggest realisation on gear came from just how impressive a micro-inverter solution is and how intelligent they are, and how future ready they turn out to be. A micro inverter is simple a small programmable inverter that sits at the back of each solar cells and is constantly talking to a gateway controller and from there to the web. Enphase have a huge lead in this market and a stellar reputation. It brought my costs up from around $7,500 to $8,700 - but it dramatically increases the life time value of my system. Micro inverters have a few very cool advantages:
- There mean time between failure is 129 years
- If a micro fails the rest of the system performs unaffected
- If a cell with a micro under performs - the rest of the array is unaffected. With string / central inverters if a single cell in a row under performs the whole row performs down to the level of the worst cell (shading one cell drops the whole string by this amount)
- If a micro performs out of specs it will generate alerts in real time - and your energy installer will notify you before you realise an issue is even begining
- Micro designs allow for any size, number and random type of cells to be placed anywhere on your roof
- Micro's are constantly tracked and reported for all systems installed world wide - they individually report to a gateway controller and you can use any smart device with a browser to see you energy creation history in real time.
- Micros only run low voltage (30 - 38 volt) current across your roof to the fuse box.
- Micros allow for later addition of battery storage (in pilot now and coming out later this year).
So I got three quotes for a 19 Trina cell (260W) M250 Micro-inverter second story roof install on a tile roof, with 7 cells placed facing North and 12 cells facing West. North facing cells produce more energy during the day, West facing cells produce more energy at the time of the day when our consumption is at its maximum. Solaray eventually beat Nicholls with a cheaper price and a much faster install. Roof brackets, meter change over and internal wiring went up on Tuesday last week (then at 2pm the skies poured down). The team came back and installed the micro inverters and solar cells on Friday afternoon and installed the gateway controller in the fuse box. Finally on Saturday one of their head engineers came in a also installed a Wattson energy meter (tracking both consumption and provision of energy) and then told the gateway to switch everything on voila we were producing! By Tuesday my systems exact configuration was loaded into their world wide web database and I could see everything it was doing.
The Wattson really helped me understand energy hogs. The big ones we switch out of hours to off peak when we can (pool pump - 1.2 kW, clothes dryer 1-2 kw, clothes washer 0.5 - 1.5 kw). The other main energy guzzlers running during the day are a big ducted air conditioner - 3.5 kw and a big electric oven 2kw. The Wattson sits next to our kettle in the kitchen downstairs and shows us moment to moment what we are drawing or feeding into the grid (and many other things).
Anyway if you'd like to see what we produce its here: https://enlighten.en...tems/LbBY574110
This shows how much energy we produce - by month, day or 15 minute intervals. The System in a fully Sunny day should produce North of 30kWh a day - but so far we have had three half days were its done between 18 to 22 kWh. At present we have created created 76.7kWh, of which 17 where exported to the Grid and the rest we consumed for our selves. If we keep that rate up the gear will pay for itself in just over four years of its 25+ year life.
Hope this is very useful information to share. I ponder how many other folk have gone solar and has it deliver, failed or exceeded your expectations.
Later this year I will consider sizing additional battery storage and see if its economical to store what we over produce and feed back in when our peak consumption - say 6 kWh for a few hours - exceeds what this system can do at peak 4kWh. So if I desire a 5 - 15 kWh storage solution is this economically sensible or should I just buy excess energy from the grid. All up I hope this solution will at least hlaf my bills going forward - if not better if I can use it wisely!