Tuesday, October 27, 2009

Our New PV System

I've been trying to get the new PV system in the last week or so, and as a result I'm falling behind on getting new entries up on the website.  Thought I would just give a short progress report on the PV system. 

I do plan to do a new section with a lot of detail on the whole PV system process with lots of detail on design, site survey, mount construction, wiring, installation, ...   probably a lot detail more than you ever wanted to see :)

After much looking at a lot of options, I chose the type of system that uses one Enphase micro inverter for each PV panel.   In this kind of system, each PV panel gets its own grid-tie inverter, which is mounted right at the PV panel.  Each inverter takes one PV panel's DC output and converts it to 240 VAC that is grid compatible.  Each inverter plugs into the next inverter in the array, and you end up with all the power from up to 15 PV panels being available as 240VAC at the last panel/inverter in the string of panels.  My system has 10 PV panels at 215 watts each for a nominal total of 2150 watts. 

I bought the system as a "kit" from Wholesale Solar -- this one...

The more common approach on grid-tie systems is to wire several PV panels in series so that the they produce a high DC voltage.  This string of PV panels are then wired to an single inverter which takes the several hundred volts from the string of PV panels and converts to grid compatible 240 VAC. 

There are pros and cons to each approach, but (I think) both are pretty simple systems that can be DIY projects as long as you are VERY careful to mind the safety precautions. 

In my system, the PV panels are mounted on the ground and are located about 100 ft from the house out in the weeds.  The wires are run underground from the PV panels to the area where power comes into the house, and the grid-tie is made there.

I rented a power trencher to dig the trench for the wires.  In our hard soil, this saved a lot of time and effort.

After some debate with myself, I settled on a rather robust mounting system made from 4X4 treated lumber.  I wanted something that would withstand the high winds we get occasionally, and that would last 30 years.  Treated lumber may not be the best choice for long life in some areas, but around here, if properly installed it lasts a very long time.

This shows the framework that the PV panels will be mounted on. 
Anchored in about in 3200 lbs of concrete!

Running the wire (in conduit) from the house to PV array.

I clamped the PV support rails and a PV panel in place just to get the spacings
right and to plan where the inverters would go (they mount to the same rails as the PV panels)

This is where I am -- just waiting for a day or two of descent weather to finish it up.


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