Viktor wrote:Can U comment on the financial part of your system - do U see it paying for itself within 10 years or so?
No, not at the current price of electricity here: 10.5c/kWh. That said, when I bought our Honda Civic Hybrid in April 2002 gasoline cost $1.65/gal. I calculated that it would take about 100,000 miles at $2.00/gal. to pay back the $4000 difference in price between the Hybrid and the normal Civic. After 11 years we have only driven the car 89,000 miles, but gasoline is now at $3.19/gal., so I'm pretty sure it has paid back the extra expense.
With Obama pushing the EPA to require coal-fired electricity providers to greatly clean up their power plants, I expect the price of electricity in this area of the country to undergo big price increases within the next 10 years, so I expect our payback will be much shorter than the current calculated time of 20 years.
Viktor wrote:I meant roof over the patio - basically just as little of support as I need to accomodate the panels and potential snow accumulation. Speaking of which - most would probably use wood for the base to place the panel on?
Well, our roof is wood, but it is covered with black paper and asphalt shingles. None of the structure above the shingles is wood. It is all extruded aluminum and stainless steel.
Viktor wrote:How many wires do I need to hide up there?
One cable and one wire for each string of panels/inverters. The cable carries L1, L2 and Neutral and there is a requirement for a bare copper ground wire.
Viktor wrote:Do I just use regular metal tubing to protect the wires?
On the roof, none of the wires are protected. They are all outdoor rated. Under the roof, the requirements for conduit depend on the environment and the type of wiring you are using.
Viktor wrote:What size electric cables do we need?
The bare ground is 6 AWG while the other wires in our system are 14 AWG to the panel. Enphase has improved this aspect and the new system uses 12 AWG for wiring the strings.
Viktor wrote:Hardware wise - what meters do U use - specific models if possible?
Each Enphase inverter contains its own meter and communicates with a central unit over the power lines. As a result, there is a lot of information about power, voltage and current collected and stored for each panel.
Viktor wrote:Apparently some of them would make U pay for the electricity U generate ((
Yes, we had one of those on our house when we first installed our system. You can see on the webpage for our system that we had an outage between February 2011 and June 2011. This was due to the old meter charging us for power flowing either direction through the meter. It's a long story, but that problem was resolved and all is well now.
Viktor wrote:Issues of microinverters vs the old ones - why micro?
Reliability is the main difference. You can expect to replace all central inverters after about 10 years, at which time the inverters you purchase today will likely no longer be available. Microinverters should have a 30 year life (guaranteed for 25) and have a calculated MTBF over 300 years and the *actual* MTBF is known by Enphase because they monitor a large percentage of the installed product. PV panels have an MTBF on the order of 600 years. So for our 42-panel array, I expect to have about 1 failed PV panel and 2 failed microinverters after 20 years. I have had one microinverter fail to date, but that may have been an infantile failure (not supposed to be considered in MTBF), but I am not sure. It was replaced at no cost to me. They updated the firmware in all of our microinverters while we were investigating, and I seem to have better solar production than I did before the failure, so I'm happy!
Viktor wrote:And at the end - can U post pictures of your system?
Here is one:
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