There are many countries (even ones in Europe were grid feed in is possible) were it is preferable to consume your own power. There are many reasons to do this where you can’t feed back to the grid or the buy and selling rate does not make sense.
There are may options provided by Victron out of the box to do this but none of them ideal or as controllable as you would want. Don’t get us wrong, Victron are excellent products, it’s just about the implantation method.
There are a number of issues when wanting to consume all your own power in the most efficient way possible:
- Often the battery backup solution does not scale to accommodate heavy consumers of power but you still want them to benefit from excess solar.
- Existing Hub configurations set to limit grid feed in, will limit at the input to the Multiplus or Quattro. Basically when solar exceeds the loads on the output of the island inverter, the input needs to be isolated so the output can vary frequency and regulate the output of the grid tie inverter (GTI).
- When the input is isolated, power cannot flow to heavy consumers on the input side of the island inverter.
- Frequency shifting and charging batteries by pushing power back through the island inverter can result in visible light flicker.
- FLA Battery charging needs to have a bulk and long absorption time without reversing the chemistry on the batteries in this time. This is not possible wit the grid isolated as the GTI cannot react to instant demands and the peaks will have to come from the battery.
- Control of other loads like hot water heating or water pumping needs to be included in the solution and also leverage PV.
- It does not make sense to scale PV systems for total off grid living in urban areas. The costs of scaling a system 3 times as large as it needs to be so you can ride out extended bad weather is prohibitive for most.
- Timing of when and how to disconnect/reconnect, charge/discharge etc is not easily controlled to suit your lifestyle or personal requirements.
Our solution is a hybrid semi off grid system that controls all these elements without disconnecting from the grid during Sun hours. A set percentage of battery power is consumed by disconnecting your essential loads from the grid overnight but not charging until excess solar is available. Once batteries are charged other loads like geyser elements are given an opportunity to consume and store energy in water.
This is done with our Smart Energy Controller (SEC) intergraded with Victron, Fronius or Kaco.
In the above diagram, the Victron Multiplus or Quattro, GTI and loads are controlled by our SEC. Normally when the Sun is shining, the Victron is connected to the grid and allows energy to pass through to loads on the non essential side. Energy is monitored and limited from being exported to the utility. This limit is set as a threshold meaning that it can be positive, negative or zero. This means that in countries where a maximum export limit is set, the GTI can still be larger than this but only export a set maximum.
The Victron will disconnect from the utility at a set time and only return to the grid if a load above a set threshold is reached or if the battery SOC reaches a set value. On reconnecting to the grid, battery charging will be held at 1A until excess PV is available.
For a detailed explanation and quotation, please contact Exsolar.