Victron Energy offers a diverse range of inverters and battery chargers; we look at designing a standalone solar battery system and selecting the best products for your installation.
Solar charge controllers - the BlueSolar MPPT
The simplest standalone systems use a solar charge controller which takes DC power from the panels and uses this to charge a lead-acid battery.
A Phoenix inverter can be used to take DC power from the battery and convert this to AC power which can be used to power your customer's appliances.
The BlueSolar MPPT charge controller is usually the best choice as it offers high performance and a wide operating voltage from the panels.
For very small systems of a few panels, or installations in warm tropical climates, the BlueSolar PWM offers a value option.
Inverter/chargers - the MultiPlus, Quattro and EcoMulti
The Victron Energy inverter/chargers act as a hub for your system.
They take AC power and convert this to DC power in order to charge the battery bank. Then when demand exceeds generation they draw on the battery in order to help meet the energy requirements.
A back-up diesel generator is connected to the AC Input of the inverter/charger allowing you to provide power all year round.
For small systems (a few kWp or less) it is often more efficient to charge the batteries using an MPPT charge controller.
For larger systems (4kWp or more) it is often best to go with an AC design and run the panels with a standard PV inverter running in "off-grid" mode.
The PV system and consumer unit are connected to the AC Output of the inverter/charger.
The unit creates a virtual grid which allows the PV inverter to generate power.
- The MultiPlus inverter/charger features one AC Input where a diesel generator is connected
- The Quattro unit extends functionality with a second AC Input which can be connected to the grid
- The EcoMulti features a built-in Lithium charger and battery
Which is the best: Lead acid or Lithium?
Lead acid batteries are a proven technology and they are the cheapest solution for a solar battery system.
The GEL and AGM lead-acid batteries are the most popular as they are designed to be maintenance free. AGM batteries offer a high charge power whilst GEL batteries maximize the cycle life.
Lithium batteries offer a significant improvement over the standard lead-acid technology. Whilst they are more expensive for the same capacity they often work out better value over the life of the system as they enjoy a much longer cycle life.
Lithium batteries are lighter, smaller and perform across a wider temperature range. They support a deep discharge to 80% depth and they can handle a very high charge rate.
The cycle efficiency of a lead-acid battery is typically around 70-80% whilst Lithium batteries can enjoy an efficiency of around 92%.
