The choices for "grid-tied" PV systems:
Solar CenTex installs "grid-tied" solar PV systems which means you are still receiving a portion of your electricity from your current Retail Electric Provider (the "REP"). The amount you get from your REP is entirely dependent on the size of the PV system that is installed: typically expect that 30% to 85% of your electricity needs can be met by solar.
While we can install battery backup systems, the reality is that 90% of homeowners in our Central Texas region will be fully satisfied with a "grid-tied" versus "battery backup" system.
You will have two choices when it comes to "grid-tied" PV systems:
- "String" Inverter: we typically use Fronius and SMA
- Module-level electronics (DC Optimizers) at each solar module; we use SolarEdge
Solar CenTex will recommend one of these to you during the design, and in some cases, we can make that recommendation during the initial site visit.
String Inverters have some advantages. Typically less expensive (~10%) than the DC Optimizer installation, central "string"inverters are good to use when your PV panels are installed on a single roof facing the same direction, with no shading. This covers many homes in our area (stop cutting down the trees, developers!). Disadvantages include a limited ability to add more solar PV panels later and a limited ability to monitor "by-PV panel" performance. We'll recommend string inverters when they make sense.
Above, we see a dual Fronius IG installation for a customer in Copperas Cove.
DC Optimizers are gaining huge support and for good reason.
A DC Optimizer attached to each solar panel ("module") brings each module to the same voltage, regardless of sunshine or shading. This allows the entire "string" of modules to operate at its peak efficiency.
This power is delivered to an inverter at the wall (slightly smaller than the ones seen above) where it is turned into AC power for the house.
The advantages include great warranties (25 years for the DC Optimizer, 12-20 years for the inverter); the ability to monitor the power output of individual modules; much better shade tolerance so if that chimney casts a long shadow in the afternoon, you won't see a significant power degradation.
SolarEdge is what we install on 80% of our residential roofs and after leaving Solar Power International 2015, we're convinced as ever that this will remain our top choice for most of our customers