Grid Outage

[ckbook]

It is really frustrating that I can't use solar electric when grid is down unless I have Powerwall. Is there a device or a way to configure that you can stop from sending to Grid during outage and utilize that power from panels?

 

[Ampster]

Is there a device or a way to configure that you can stop from sending to Grid during outage and utilize that power from panels?

Yes a hybrid inverter can do that. You would need to connect that to a battery pack and they could operate much like the powerwall does. Depending on the sophistication of the hybrid inverter it may have much of the functionality of the Powerwall. It could disconnect from the grid to protect linemen working on the dead grid or one could make that disconnection manually. The hybrid inverter could manage the power generated by the solar panels and distribute it to the house loads with any excess going to the battery pack. If the pack is full and the house load cannot use all that the panels produce then the inverter would shut down the panels. This is often called AC coupling. It is not simple to emulate everything that the Powerwall does in one system. So far, Sonnen is the only complete package that I have seen that will do what the Powerwall does. The price I was quoted six months ago was not competitive with the Powerall quote. However lead times may be shorter.

 

[Nikki's Dad]

Not sure this will be relevant to your situation but for what it is worth ... I have a solar panel system tied to the gird but no battery storage system. I was surprised to learn that my system would not generate when the grid went down. My installer said it was a regulation as the utility companies did not want power from a solar panel system leaking into the lines of the grid while repairmen might be working on them. Something to consider.

 

[ckbook]

Yes that is what I was told also. But I was thinking there has to be a device or way to configure the system to not send power to grid during outage. Haven't had chance to investigate hybrid inverter mentioned above, but maybe that is what is needed.

 

[Ampster]

Not sure this will be relevant to your situation......

Yes, that is a good explanation of the safety requirement of grid tie inverters and why they are not designed to produce power when the grid is down. As a practical matter grid tie inverters are less expensive than hybrid inverters.

 

[Ampster]

But I was thinking there has to be a device or way to configure the system to not send power to grid during outage.

It is simple to disconnect a grid tie inverter from the grid. To make the grid tie inverter produce power you need to spoof the 60 cycle AC so the grid tie inverter can sync up. That is the easy part. Managing the output of the panels is where is gets complicated. In the case of the grid it presents and infinite load to the panels via the grid tie inverter. In other words the grid can take whatever the panels produce from sunrise to sunset over and above the house load. The grid is acting as a huge battery. As you can imagine both the house load and the solar generation vary from minute to minute. When disconnected from the grid something has to act as a buffer and that is where batteries come into play. As I mentioned earlier, it is not simple and there is no simple device to do all of the above. It takes a system approach to get the functionality you are looking for.

 

[cwied]

SunnyBoy has a "Secure Power Supply" feature that basically provides one outlet on the inverter that is powered even if the grid is out.

As others have said, if you want to power your whole house (or a significant portion thereof) you need something fancier plus a transfer switch to disconnect from the grid. It turns out the Powerwall is one of the cheaper options for the capacity it provides if that's what you're going to do. Also the transfer switch in the Gateway is pretty fast - almost fast enough for all equipment to stay up when an outage hits.