In recent years, solar power generation technology has become increasingly mature, and more and more industries have begun to try using solar power generation instead of directly purchasing electricity from energy companies. This can not only save a lot of electricity expenses for homeowners and reduce their carbon footprint but also help homeowners improve their power supply autonomy to a certain extent.
This advantage makes solar power systems one of the optimal choices for providing power to camping vehicles that require long-term off-grid operation. After determining the rough equipment connection diagram, you still need to carefully choose some important components. This article will introduce how to choose an inverter for your DIY solar system.
1. Selection of wattage size for inverters
Generally speaking, the wattage of an inverter mainly depends on the load capacity of the solar energy system you DIY for your camping vehicle. Generally speaking, the wattage of the inverter should be slightly larger than the wattage of the supplied load. For example, if your overall load size is about 1200W, it is recommended that you use an inverter with a size of 1500W or above.
But in practical applications, there may be a special situation: surge. Load surge behavior refers to a sudden increase in the power required for a certain electrical appliance to start, and the instantaneous power at this time may be much higher than the power of the appliance during normal operation. For example, when the air conditioning on your camping vehicle starts running, the instantaneous operating power of the entire vehicle may reach 3000W.
To cope with this situation, typical inverters have two power ratings: continuous rating and surge rating. Continuous rated value refers to the maximum power that an inverter can continuously supply, which is the wattage of the inverter slightly larger than the overall load size, as mentioned above. The surge rating refers to the maximum power that the inverter can provide in a short period.
If your power supply includes appliances with compressors, motors, and transformers, the surge power of these appliances may reach 4-7 times their operating power. Therefore, the minimum surge rating of the inverter you choose also needs to meet the surge power of these appliances during startup.
2. Selection of inverter types
Before choosing the type of inverter, we need to first understand a professional term: harmonic distortion (THD). This is a term used to measure the deviation between the waveform emitted by a certain inverter and the pure sine waveform. Generally speaking, inverters can generate square waves, sine waves, corrected sine waves, and near-sine pulse width modulation waves, among others.
Among them, the waveform generated by a pure sine wave inverter is the closest to that of a pure sine wave, with harmonic distortion usually below 3%, while the waveform generated by a modified sine wave inverter typically has harmonic distortion between 10% and 30%.
In summary, we generally recommend using pure sine wave inverters instead of cheaper stepped waveform inverters. The voltage graph generated by this pure sine waveform inverter is smooth rather than stepped, which is more friendly for some sensitive equipment. Inverters that generate square waves and corrected sine waves may damage the load on the circuit due to excessive voltage fluctuations.
Secondly, despite being inverters of the same type of waveform, there are still many price differences. For example, a typical cheap inverter may maintain a current of 3-5A even when there are no electrical appliances in the camping vehicle, which may cause safety issues.
So this type of inverter requires you to pay attention to keeping it turned off at all times when the inverter is not in use. However, slightly more expensive inverters do not experience this situation, as their current is negligible when running without any electrical appliances, allowing them to remain in the on state at all times without the need for manual shutdown.
3. Use an inverter charger
Generally speaking, not all inverters need to be equipped with a charger. But for DIY solar systems for camping vehicles, adding shore power is necessary. It can help you convert the 12V power supply of the battery to a 110V power supply, compatible with the possibility of charging camping vehicles on the power base or household socket, which can greatly assist the normal operation of high-power appliances in camping vehicles, such as air conditioning.
4. Other related issues regarding inverter selection
4.1 Minimize the harmonic distortion of the inverter to improve the service life of various electrical appliances in the camping vehicle
Generally speaking, the higher the THD of an inverter, the greater the likelihood of it causing noise or interference in the electrical system. For sensitive devices, this may cause them to malfunction or overheat, greatly reducing their lifespan.
For example, this may result in inaccurate or unable to locate navigation and positioning inside the vehicle, as well as engine failure or unstable operation in camping vehicles. To ensure that your inverter does not cause damage to the electronic devices and expensive appliances inside the camping vehicle, it is generally recommended to choose an inverter with a THD of less than 3%.
If you have more demanding electronic devices in your car, you can choose to install filters to help reduce the remaining small amount of harmonic distortion.
