Post #9675

If you are considering an inverter, there are two classifications... "off grid" and "hybrid". Off Grid has an internal transfer switch that either powers your load from the AC input (grid /gen) or from it's internal inverter. 100% of your load will be supplied from the generator or grid when they are available. These inverters to monitor the incoming AC voltage and frequency and if it gets too far out of spec, they will disconnect and supply power internally from batteries instead. Hybrid inverters have the ability to synchronize with the grid or generator. This gives them the ability to load share with the incoming power supply. For example, you have a small 1kw generator that cannot possibly run your house. If you run your microwave oven and the load suddenly goes to 1500w, your 1000w generator can't supply this power... so 1000w comes from generator and 500w comes from your batteries. When the load is below 1000w, the excess power available from the generator is used to charge batteries. This allows you to use a cheaper generator. Victron has added to this "blending" in their inverter software. If you suddenly change the load on a generator it will cause it to slow down a bit before the throttle can respond. If the generator slows too much, the inverter may think it is out of spec and disconnect. To solve this Victron inverters will take 100% of the surge and then slowly back off what they are producing from the battery. Over a period of 60seconds, they will slowly give over more and more load to the generator. The result is a sudden increase in load will gradually shift to your generator. A friend here running SMA inverters used this power limiting feature to run his house off a small extension cord. He programmed the inverter to never pull more than 1500w from the grid to avoid "demand fees" from his utility provider. The result was he could run hte microwave, hotwater, etc and it never pulled more than 1500w from the grid. He used this methodology until he got his solar panels installed.