So I'm getting close to pulling the trigger on a solar PV system at home. Have spent the past few weeks reading, e mailing and talking to so many sources my head is spinning. It's a really strange industry, seemingly flooded with cheap and nasty companies just trying to undercut each other in order to sell as many units as possible before closing up and running for the hills. Amongst these are the reputable, genuine companies who actually know more than can be read on their web page and actually care about giving you the right advice and product. It's a slippery course to navigate but I'm slowly whittling away the cheapos and rip offs and am settling on a particular configuration of 5.4kw system with Fronius single phase inverter and panels either by Jinko or et solar.
Quotes for identical systems in terms of these components vary from $5300 to $7700, which is huge in terms of percentage. They all spruik certified electricians, installers, system engineers, cec accredited independent inspections same warranties on products and workmanship, so the hard part is believing they'll still exist long enough to honour a 25 or even 10 year warranty..
So where is the rest of the value? One company offers lifetime system analysis so as to be able to inform us on more beneficial energy usage patterns, or issues with power generation etc, so that could be handy but not essential.
Who around Melbourne or within Victoria has had a system installed, and what would you recommend to help sift through the shit and not get ripped off but at the same time not just assume more expensive is better? I'm leaning toward a company that's about middle ground price wise, seem pretty honest, get decent independent industry reviews and are local and been in business for years. But any advice or experiences would be great to hear before I throw down 6-7k.
I installed a 6.4kW system on my house in QLD about 8 months ago, and whilst it is not Melbourne, I too anguished over all the literature, hype and bullshit during the selection process. I'm also an electrical engineer so have a pretty good understanding of what is truth and what is horseshit coming from the salespeople I dealt with from the prospective vendors.
To address some of your comments and some things in general:
1) I'm fairly certain that ALL installers need to be CEC accredited these days - the industry has cleaned up it's act after a lot of dodgy installers put systems in and people's houses burnt down.
2) Premium panels usually have a much better performance guarantee eg. guaranteed electrical output after 25 years - this is what you should be looking at in terms of degraded performance over time. You can calculate this out as an actual cost (ie. better output for longer saves you money) and determine if a more expensive system with better panels will cost you less in the long run. I went with LG Neon 2 panels (19.2% efficiency, and a 25 year output guarantee of around 83% which is very good) - they are also 320W panels, so it maximises output per square metre of roof space if you have limited roof area.
3) These 'lifetime system analysis' offers are crap IMHO. All they do is set up the inverter to connect to your home WiFi and send data back to a centralised database that they can pull data out of and send you fancy looking reports. If you keep an eye on some basic things yourself, it's easy to tell if the system is healthy and working as intended. If, however, you're a set and forget sort of person, paying a premium for a monitoring service will mean you will be alerted quickly to any system faults that result in no power output (rather than discover it yourself when you get your next power bill). If you have a new 'smart' energy meter, you can generally get access to your metering data from your retailer, and get an hour-by-hour view of you home energy usage, including solar output. That's a free service from your retailer (well it is with AGL).
4) Your roof area, pitch, shading and which direction it's facing will be important factors to consider. A ~25 degree pitch north facing roof with no shading is ideal, and will also mean a much simpler and cheaper install. Why? Because you'll only need one 'string' of PV panels and central inverter. Where your roof area faces several directions and when there is partial shading needs some more thought to maximise the efficiency of the system. My roof for example had NE and NW facing roof areas, but very little shade on each. I went with a Fronius inverter that supported 2 PV array strings (two independent arrays of panels back to the one inverter). It allows the inverter to maximise the output of each roof face independently of the other - the NE facing roof cranks out more in the morning, whilst the NW roof performs better in the afternoon.
5) The problem with series connected PV panels is that the whole 'string' only performs as well as the poorest performing panel in the string. If one panel is faulty, the whole string goes down. If a couple of panels are partly shaded during the day, the whole string output reduces accordingly. Part shading of roof area makes a good case for micro-inverters - each panel essentially has it's own inverter and the maximum possible output from each panel is ensured all the time, regardless of shading on other panels. Plus they are generally smart devices and you get masses of wonderful marketing data from them like how each panel is performing compared to the others. Micro-inverter systems are also more expensive, and only give you marginal performance gains over central inverter systems when you have no shading issues. I considered it when looking at my system, but the economics didn't stack up because of my roof configuration. I also don't like the idea of having sensitive electronic equipment sitting up on the roof in the baking heat year in year out, getting shat on from the heavens all the time. A cheaper alternative to micro-inverters for partial shading is a chainsaw...
6) There are some physical limitations when connecting a solar system to your house (bit of simplified electrical theory here). For an inverter to send excess power back to the grid, it has to increase it's output voltage so that it's higher than the grid voltage. If this voltage is too high, it will start messing up things in your house. Most electronics can tolerate over-voltage for short periods, but it will reduce operating life over time. Think electronics primarily, and fridges. Modern inverters will generally have a maximum output voltage to help protect your household goods, but this limit may also prevent the inverter from sending all available solar energy to the grid, reducing your feed-in kWh (not that you get much $ for them these days, but it still adds up over time). If you have a house with 3-phase power, then you can largely avoid this problem with larger Solar PV systems (>=5kW or so). The other limitation we have in QLD (other states may be similar) is that above 5kW, the inverter needs to deliver power to the grid with a power factor of 0.9 - it's an AC electricity concept (phase relationship between voltage and current), but in net terms it means you only get 90% of the output from your inverter. This is done to help reduce over-voltage action on the local electricity grid. So my 6.4kW PV array is connected to a 6kW inverter, but is limited to 5.4kW of actual electrical output. The large 6.4kW array is still beneficial in that I get 5.4kW of available power for longer during the day (kicks in earlier and cuts out later). Because my 6.4kW array is split across two different facing roof areas, it doesn't usually peak more than about 6-6.1kW on any given day, so I'm not losing much by only having a 6kW inverter (instead of one sized for the maximum PV array kW).
All of the above should be part of any well-considered offer you might receive from a solar company. Bear in mind though, that they can't afford to do the 'detailed design' up front for each customer to ensure the best system for the application - they couldn't compete. So they dazzle you with marketing spin on the basis that you're an uneducated buyer and will trust their 'professional' recommendations.
Hope this provides some background to inform your own decision making. You mileage will obviously vary, so do your own homework and don't rely solely on the above.