When do I select Solar Control Mode on a Microcare Inverter?
Solar control mode can be described as an OFF-Grid solution with AC backup. The Inverter mainly runs in the Inverter mode. The batteries power the load via the Inverter circuitry. Renewable energy charges the batteries. The system will run from battery power until the batteries have discharged to a set level. At this level, the load is disconnected from the batteries and the load is connected to the grid. As soon as the batteries are charged to a set level, the Inverter switches to Inverter mode and the load runs from the battery powered Inverter.
What is the purpose of an MPPT?
An MPPT allows you to take advantage of the mathematics behind power conversion and allows maximum power delivery from the panel. Let’s look at a typical solar panel (the values will be adjusted to make reading/maths easier). Read more here
How do i size a system? Click here
What size fuse do I require for 4 x 200AH batteries?
The battery fuse is based on which Inverter you are using and not so much the batteries. The calculation to use is (INVERTER (W) / BATT (V)) so as an example for a 5000W inverter divide the inverter wattage by the battery voltage, 5000/48=104A, so you would need at let a 104A fuse but to compensate for surges there are 125A fuses available.
What amperage is required for the 2 pole change over switch?
I assume the change- over switch you refer to is the switch to bypass the Inverter power? This can be any amperage based on the load, it is not really meant for protection at all so you can install a 63A without a problem.
What size Earth leakage is required for the Inverter?
The earth leakage that can be used depends on the through put of the Inverter, the Inverter can generate 25A but can pass through 200% of Eskom power so it can pass through up to 50A. I would say for the earth leakage a 63A unit is fine.
Seeing that the electrical supply is 3 phase should I install a three phase surge arrestor?
Yes I would protect all three phases instead of just the one. If there is a close strike you could get arcing from the other two phases to the phase that the Inverter it is connected to, it is just safer.
Should I isolate Eskom or Main power for maintenance?
Also remember never to disconnect the Neutral from the Eskom input. The isolation breaker on the Inverter input should always be a single pole (Live Only) breaker and to distinguish the sizing you will again need to consider the maximum bypass current of 200%. If the Neutral is disconnected this will result in a floating earth.
Scenario: If I go with two banks of 3 x 305 w panels VMP 36.6 v/ Imp 8.33 A with 3 panels on the north side roof and 3 on the west. Will I need two MPPT ( Size) as well as 2 surge arrestors and fuses?
Each bank of solar panels should be on their own orientation, so one bank North and the other West, never mixed. I would advise by all accounts that you should use two MPPT’s. This is due to the MPPT’s Maximum Power Point tracking. Each array at different times of the day will have a different VMP voltage, the North facing will be higher in the morning and midday, the West will be higher in the afternoon. Hence in the morning the VMP of the West facing array will be very low and will pull down the voltage for the north facing array, confusing the MPPT and vice versa in the afternoon. This will seriously drop your power production. For a 48V battery system, you could use two 2x 20A LCD MPPT’s if required calculated using the formula Wp/44V, 915W/44V=20.78A. We use 44V to calculate because the voltage can go as low as 44V in the mornings. Yes you would need 2x surge arrestors and fuses for each MPPT.
What size PV surge arrestor do i need?
The sizing of the PV surge arrestor is dependent on the max VOC of the MPPT, in our case 150Vdc. You surge arrestor should not have a higher surge voltage than this, I know you can get a 140V unit.
How does the Microcare Bi-Directional Inverter operate at 200% of the rated output?
For example can the 1kW supply 2kW. When an overload occurs the Inverter will switch into the turned off-mode. A warning message “UPS Overload” will appear on the display and the Inverter will beep continuously until the enter button is pressed. Disconnect the load from the Inverter. The Inverter can now be switched on by simultaneously pressing the Enter and Menu Up button. Also: If the grid fails or Load shedding takes place a 1kW Inverter can then only supply 1kW of power to the load. If the load exceeds 100% of the Inverter power, the Inverter will also shut down due to overload. Default Setting: IF AC INPUT = ON AC OUTPUT = NOR With the above selected a 1kW Inverter will supply 1kW of power when connected to the grid AC OUTPUT = 200%: IF AC INPUT = ON AC OUTPUT =200% This setting will allow the Inverter to supply 200% of the rated power only when the Inverter is connected to the grid. *This menu can be accessed from the System Setup Menu* Note: This mode should not be selected when the Inverter is programmed in Solar Control Mode, The 200% feature is only available on models manufactured later than June 2015, “Connected to the Grid” means as long as Eskom is connected. The Inverter may still allow a surge or short term operation of the load at 200% when connected to batteries and is useful when starting motors. While the Inverter is connected to the grid it may supply 200% without overload indefinitely.
Can the Microcare Inverter switch up to 200% of the rated Inverter power in solar control mode?
Yes. From the 1st March 2016 this feature will be available on the 5kW 48V, and the 10 & 15kW Inverters.
Remember the Inverter can only produce its rated power, in other words an Inverter rated 5kW can only produce 5kW of power.
To set this up you will need to go to the following option on the Inverter setup menu.
IF AC INPUT = ON AC OUTPUT = NOR
IF AC INPUT = ON AC OUTPUT = 200%
If the 200% option is selected the Inverter can switch 200% of the rated power when programmed in “UPS Mode, Normal Sense mode” BUT only while the grid is available.
In other words: a 5kW Inverter will be capable of switching a 10kW load
If a load exceeding the rated power is connected, the Inverter will trip due to overload
The reason for this feature is that many users have requested to have the function available for Off-Grid solutions where the grid is available.
We refer to the above as an Off-Grid solution with grid assist.
For Off-Grid solutions with the Grid connected we will program the Inverter as “UPS Mode, Solar Control ”. you will also need to change the following: IF AC INPUT = ON , AC OUTPUT = 200%
In this mode the Inverter can switch a load of up to 200% of the Inverter capacity when connected to the grid. When the Inverter is programmed to solar control mode and is operating in the Inverter mode – the Orange LED comes On, meaning the load output AC is generated from the batteries. When the load exceeds 100% of the rated Inverter power, the Inverter will disconnect from the batteries and connect to grid power alone.
The load stays connected to the grid until the load is reduced to 80% of the Inverter capacity and then switches back to Inverter mode.