Jason RothmanMay 16, 201839751
A string inverter is a stand-alone box that is typically installed close to your fuse box and electricity meter. The simplest explanation is that it changes the DC current into AC current that we all use for electricity here in the U.S. There is typically only one, or possibly two, string inverters on each residential solar installation.
Micro-inverters perform the same basic function but are installed underneath each panel on your roof. Each of these micro-inverters is about the size of an internet router. The big difference is that a solar panel installation with microinverters will have the same number of microinverters as there are solar panels.
Both types of inverters are useful and it really depends on how your solar panels are laid out before you need to choose one inverter over another.
A string inverter functions in a series circuit with their usually being 6-10 individual solar panels in what is known as a string.
The advantage of a string inverter is that you only need one of them. If anything is going to fail in a solar system it is likely to be the inverter and so it is less likely that as an installer you will have to go back to a job. Cost is another advantage, a single string inverter on a solar panel installation is usually cheaper than installing micro-inverters.
If one panel is shaded or is not working properly, it can take the whole system down. All the panels are attached or strung together, and if there is an interruption in the string, then the electric current does not work.
When solar panels are in a string the voltage is reduced to the voltage of the lowest voltage panel in the string. Sometimes you lose some efficiency because the current is reduced to the lowest voltage. You may not have the right roof for string inverters. If you need to have solar panels placed in different directions, as to avoid shade or to better capture the sun’s rays, then a string inverter just won’t work for you.
A microinverter functions in a parallel circuit. To simply put, a standard inverter will cap the electricity production of each panel by the lowest producing panel on your roof. A micro-inverter, on the other hand, will take full advantage of the production of each individual panel. It will convert the power generated by each panel to the grid voltage.
The core advantage of using microinverters is that theoretically, you can yield more solar electricity. The reason for this is that there are slight differences in voltages between solar panels. When solar panels are in a string the voltage is reduced to the voltage of the lowest voltage panel in the string.
If a solar system is facing multiple angles then micro-inverters are the way to go. Or, if you have shading issues from trees or a large chimney, again micro-inverters would be best. In these situations, the solar panels will be producing different amounts of electricity at different times of the day, but micro-inverters will ensure you harvest all of the energy,
Optimizers are an option for standard inverters as well, which function very similarly to a micro-inverter. With an optimizer, you still have a standard inverter, but you also have optimizers for each individual panel combating production differences. There are other aspects to consider as well. Micro-inverters typically have 25-year warranties while standard inverters typically have 5 or 10-year warranties. Micro-inverters and the add-on optimizers both offer an additional perk in system monitoring as well. With either of these devices, you have the ability to track the production of each individual panel, while with a standard inverter you only can track the production of the whole system.
If you were to expand your system in the future, micro-inverters are simple to add one at a time. However, with a standard inverter, it would be more costly to add another full unit. To sum it all up, micro-inverters definitely add value but are only recommended if you have panels facing multiple orientations or you have shading issues. Otherwise, the less expensive standard inverter is usually more cost effective.
The main disadvantage of microinverters is the price. They are typically a $1000 or so more expensive than a string inverter on a standard 5kW residential solar installation. The second disadvantage is that you have as many inverters on your roof as you have solar panels.
Although microinverter manufacturers sell the ability to monitor each panel as a benefit of micro's (and it is) they then don't include the monitoring that allows the customer to do this. They only allow the installer to see the panel level data from your system and not you as a customer unless you agree to buy the higher level of monitoring as an upgrade. This means you as a customer only see system-wide monitoring information not what is going on with each panel. A skeptic would say that the reason they do this is to protect them and their installers from support calls related to broken inverters. It is very difficult with only system-wide monitoring data to determine if only one or two inverters out of 25 or so have failed.
If you are a homeowner, it’s good to understand the basics of a solar panel system, but you don’t need to know the exact details. Here at HahaSmart, we connect homeowners to their local network of HahaSmart Verified Solar Installers who will answer all your questions and professionally install the solar system.
Design your home solar now and get multiple quotes for your budget by using our Online Design DIY tool. Our goal is to make solar easy, affordable and fun so feel free to start your journey to energy freedom with HahaSmart.
For information relating to going solar don’t forget to visit our solar blog section for more handy guides and articles.
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