First, some simple notions…

First, some basic electrical concepts regarding solar panels, inverters, and batteries. We all have appliances that can be both plugged into the mains and powered by batteries. For example, you might have a clock radio that you plug into the mains. You have a power supply that you plug into an electrical outlet, and the other end of the cord (often round) plugs into the clock radio. And you can put batteries in your clock radio that will work in the event of a power outage. In reality, this appliance only runs on direct current, the type of current provided by batteries. The job of the power supply is to convert the alternating current in your home into direct current so that the clock radio can use it.
Solar panels are a bit like the same thing, but the other way around. They're like large batteries with their + and - sides. Like batteries, you can connect multiple panels together and thus increase the electricity produced. The only difference is that batteries produce their current through a chemical reaction, and panels use the sun.

Inverters

The panels (a huge battery, you might say) produce direct current, but your home needs alternating current. Just like with a clock radio, we need some kind of power supply to convert the current, but this time from direct current to alternating current. This is the job of an inverter.
The panels are connected to the inverter, and the inverter is typically connected to the input of your main electrical panel, like the cables that come in from your electricity supplier. For panels installed on a roof, the inverter is usually positioned a little further away from the panels. In this case, the inverter converts the direct current into alternating current for all the panels. There are "micro-inverters," with a micro-inverter for each panel. This is advantageous because if one panel fails, the others can continue to operate.
In France, there's a general rule that your installed capacity cannot exceed your electricity supply contract. If you have a 9 kVA contract, you can't have more than 9000W of panels. This is also to limit your injection, as the French grid can't support everything (see below).
If you have solar batteries, the inverter takes care of storing your excess production in the battery in the form of direct current, and will convert the current in the battery into alternating current when you need it. An important thing to understand: the inverter itself needs to be supplied with electricity in order to perform its function as a current converter. Most solar panels and solar batteries do not work if there is a power outage. This is mainly for safety reasons. First, the inverter cannot work because it is no longer supplied with electricity. But also, if your inverter were to work even during a power outage, and you produce a lot of electricity, this electricity cannot be injected into the grid because it could electrocute the personnel working on the problem of the outage. So the panels stop working during a power outage, and also the solar batteries, due to lack of power supply (except for some very recent solar batteries, which offer to power a small low-power "emergency circuit").

Plug-and-Play (PnP) panels

Another type of solar panel is called "Plug-and-Play." These panels have a plug and are plugged directly into an electrical outlet, saving you the hassle of hiring an installer. The inverter is positioned behind the panel so that the current flowing into the outlet is alternating current, ready for use in your home.
Plug-and-Play (PnP) panels have a few additional safety considerations to consider. Since they are plugged directly into an electrical outlet, the watts produced by the panels are added to the watts that may already be present in the circuit (appliances could be plugged into other electrical outlets on the same circuit). Since the standard circuit breaker on a circuit of electrical outlets is 16A, you should not exceed 16 x 230V or 3680 watts. However, the circuit breaker "does not see" the watts put into the circuit by the panels, and therefore may not trip when it should. The wire cross-section must also be taken into account. This is why it is highly recommended not to connect other appliances to a circuit where there are PnP panels, and to connect the panels directly to the circuit breaker (although in this case, not plugged into an outlet, they lose some of their PnP concept). This is also why PnP panel manufacturers recommend not plugging more than 4 panels into a socket (4 500W panels = 2000W). Although the circuit can theoretically support 3680 watts in total, the electrical outlet itself, if it is not of good quality, may not support this current. Sometimes, to be really safe, we even see manufacturers whose recommendations are draconian: no more than 800W on a circuit.
The electricity distribution manager (ENEDIS in France) also limits the number of PnP panels you can have. Let's remember the main purpose of PnP panels: to provide the "resting electricity" for your home. What is resting electricyt? It's the electricity consumed by your home when no major appliances are running. It's the electricity for your fridge, your freezer, your internet box... it's approximately 500W to 1000W depending on the household.
The distribution network in France would not be able to support the current if everyone injected a lot of surplus into the network. First of all, you cannot be paid for the surplus from your PnP panels that you inject into the network. In theory, you are not even allowed to inject current from the PnPs into the network at all, but ENEDIS tolerates a little injection (electrically speaking, they are obliged to accept a little injection because in any case, the electricity cannot go anywhere; it MUST go somewhere and if your house does not consume it, the only way out is the network).

Your town hall and the electricity distribution manager

In France, if your PnP panels are not installed more than 1.80m from the ground and you have a maximum of 3000W of panels, you do not have to declare anything to the Town Hall. You must, however, inform ENEDIS that you have PnP panels via a form on their website (this is a declaration, not a request). The 3000W limit is used to limit the amount of watts that you can inject into the grid. ENEDIS assumes that if you have 3000W of panels, they will not produce 3000W all day long. Even if you produce 3000W, your house uses a good portion of these 3000 watts. In general, you produce 2500W, your house uses 1500 or 2000W, so you only inject 500 to 1000W. This is an injection into the grid that ENEDIS can "tolerate". In any case, even if you produce 3000W and there is nothing running in your house, the 3000W that you will inject are still "tolerable". Note that if you already have a self-consumption contract with surplus injection, your injection limit normally increases to 6000 watts.

How does SWOpti allow me to have more than 3000W of PnP panels?

Take the case where you have three sets of PnP panels (of course, all connected to different circuits or better, directly to your electrical panel!), each set capable of producing 3000W. If you produce a total of 7000W and your house consumes 4000W, you will not have problems with ENEDIS because you would inject 3000W, the maximum (the maximum normally increases to 6000 watts if you already have a self-consumption contract with surplus injection). But if your production increases and/or your house's consumption decreases, you would be injecting more than 3000W; you would exceed your injection limit. If you produce 8000W and the house only consumes 3000W, that's 5000W of injection, 2000W too much. Since SWOpti takes all its measurements every 5 seconds, it will detect this and will actually turn off one of the sets of panels. If the set of panels that SWOpti turned off was producing 2500W, your new production is 5500W, less the 3000W consumed by the house, leaving 2500W of injection. You can therefore have a large quantity of panels and SWOpti will ensure that you remain in compliance with your injection limit. The nature of PnP panels is that you can buy them as you go, so you can get additional panels whenever you want and your budget allows.

SWOpti is composed of 4 elements:
• A mini PC with SWOpti and Homeseer software installed
• Current clamps to measure your consumption/production
• Modules that communicate with the appliances to be controlled/monitored
• A controller connected to the mini PC which communicates with these clamps/modules

They say "Necessity is the mother of invention." That's how SWOpti came about. Its creator has a water heater that runs for about three hours a day. He also has solar panels, and in a day, these produce more than enough electricity to power the water heater. One day, towards the end of the morning, he noticed that his water heater was drawing electricity from the grid, and it was very cloudy outside. This continued for an hour (2500 watts at €0.20 per hour = €0.50). Then the sun came back in full force, and the electricity to complete the last two hours of the water heater's operation was provided by the solar panels (cost of €0). If this same scenario occurs for a month, it's €15 unnecessarily paid to the electricity supplier, and that amounts to €180 per year. Not happy with this observation, he was looking for a way to automatically operate his appliances only when there is enough solar production. He found quite a few mobile phone apps that simply tell you what you are producing and sometimes your consumption, but do nothing to truly optimise self-consumption by turning appliances on/off. Or, it can only control one or two appliances. Or, you have to log into an external website with a username and password to see what's happening in your own home (what if the internet is down?). Or, these apps use simple weather forecasts for your zip code to "suggest" turning appliances on or off, without taking into account what's happening on YOUR roof. Finding nothing satisfactory, he decided to create the software himself.

With SWOpti, you make a list of appliances you want to control/monitor and the order of priority for them (in your home, you might give your electric vehicle charger a higher priority, and the water heater will have second priority). When you produce more than you consume, your solar system sends the surplus to your energy supplier. You may be paid for this electricity, but probably not at the same price as you would have to pay to get the same amount of electricity from them. Instead of letting this electricity leave your house, SWOpti will turn on an appliance with the highest priority that is not already turned on.

But what's great is that it works the other way around! If you produce 4000 watts and consume 3000 watts (including your water heater with its 2500 watts), your surplus of 1000 watts is sent to the grid. If someone turns on a 1500 watt hairdryer, you will be forced to "take" 500 watts from the grid. Although SWOpti does not directly control the hairdryer, by taking its measurements every 5 seconds, it will detect that you are consuming electricity from the grid, and it will try to turn off an appliance that it controls in order to reduce or even eliminate these 500 watts. If it temporarily turns off the water heater, this will "give" 2500 watts to your home, and therefore the "missing" 500 watts. You will even inject 2000 watts into the grid. As soon as your solar production increases and/or the hair dryer is no longer used and/or your consumption decreases elsewhere in the house, SWOpti will turn the water heater back on.

What about SWOpti's other features?

SWOpti doesn't require any intervention from you to run. You can monitor everything that's happening by connecting to its control screen from a web browser (inside or outside your home).

The control screen shows all energy flows: solar panels to the house, to the outside grid, or to your batteries (if you have any); electricity you receive from outside or from your batteries; and your home's total consumption. The status of your appliances and the number of watts they are currently consuming are also displayed.
• If you want to force an appliance to work (even if you don't have enough production), do a "Force On" or on the contrary a "Force Off".
• You can also add the number of minutes to stay in these modes with the "Timed Force On" or "Timed Force Off" functionality.
• Want your Timed Force On to only start at a different time? Create a Deferred Timed Force On. This is useful, for example, when someone takes a shower at 6 a.m. before leaving for work, and you want to make sure there's enough hot water for that person. You set a 60-minute Deferred Timed Force On starting at 5 a.m. And you can configure this feature to skip weekends and Wednesdays, since the person doesn't work on those days.
• Does your pool filtration need to run 5 hours a day? Do a 5-hour Guaranteed On. At sunrise, SWOpti will start a 300-minute Timed Force On for this appliance. Like an appliance in "Normal" mode, SWOpti will turn the filtration on and off during the day depending on your solar production, but the remaining minutes will only go from 300 to 299, etc., if the filtration is actually on. If the 300 minutes are reached during the day, you can tell SWOpti what to do next with the filtration. However, at sunset, if the appliance has not run for its 300 minutes, SWOpti will start a Timed Force On for the remaining number of minutes. Of course, if you benefit from off-peak hours, SWOpti will launch this Timed Force On at the start of the next off-peak period.
• Are you on the French EDF Tempo rate scheme? With an exorbitant rate of around €0.70 per kWh during peak hours on a red day, let SWOpti handle it! Note that the SWOpti control screen indicates the current colour and tomorrow's colour. At 10 p.m. the day before a red day, SWOpti will Force On the appliances you have specified (normally water heaters, electric vehicle chargers, etc.). The goal is to get these appliances working before 6am, in order to have hot water for the day and a good charge for your vehicle and thus not consume any electricity at all on the red day for these appliances. So at 6am, SWOpti will initiate a Force Off until 10pm for these appliances, adding electric heaters, etc. (you decide which appliances are affected).

SWOpti and heating

SWOpti can control your electric radiators (and in some cases, your heat pump). Standard setpoint temperatures are already programmed for each radiator, but you can set a setpoint temperature for each radiator individually, down to the half-hour, and this can be different for each day of the week. The savings are substantial when your radiators are controlled by SWOpti, and here's why. Let's look at what happens without a SWOpti: You have 5 electric radiators that each consume 1000 watts. Depending on the temperature in each room, a radiator will click on and heat the room and turn off with another click in maybe 20 minutes. Each radiator does this independently; there is no orchestration between the radiators. If your solar production is 3000 watts, and 1000 watts are used by other appliances in your house, then you have 2000 watts available. If two of your radiators are on, that's good, you're making good use of those 2000 watts. But if three radiators are on, you'll need to take 1000 watts from the grid. This is not good because you have to pay. SWOpti, on the other hand, will manage the radiators to avoid consuming electricity from the grid as much as possible.

You're probably familiar with backup inverters called "uninterruptible power supplies (UPS)" where you plug a computer into the battery and then plug the battery into an electrical outlet. Normally, your home's electricity keeps the battery charged, while at the same time, current flows through the battery to power the computer. If there's a power outage, the battery instantly takes over to continue powering the computer until the mains power is restored. If the battery is properly sized, it could be used to power a refrigerator, freezer, lights, etc.

Indeed, a modern freezer consumes 200 watts for 20 minutes (when the motor/compressor is working), then only a few watts (or even 0 watts) for 40 minutes. In terms of kilowatt-hours, this means that the freezer actually consumes 200/3 watts or 67 watts per hour. Neglecting the few watts consumed during the 40 minutes, it is easy to understand that a battery with a capacity of 1 KwH (1000 watts) can power this freezer for an entire night and even more (1000 watts / 67 watts per hour = 14.92 hours, let's say 14 hours).

The battery can be installed "locally," i.e., next to your freezer, or, if you want to power your lighting circuit, the battery can be positioned near your electrical cabinet. In this case, the circuit breaker that currently powers your lighting circuit will power the battery, and it is the battery that will power the lighting circuit.

Using free electricity from the sun, SWOpti will recharge the battery during the day, and as this electricity passes through the battery, the freezer will also be powered for free. At sunset, SWOpti "cuts" the battery, simulating a power outage, and the battery takes over. That said, if there is an actual power outage during the day, the battery will be able to continue powering your freezer, thus protecting its contents.

What are the advantages of an MNR compared to a solar battery?
• An MNR is MUCH cheaper than a solar battery
• A solar battery needs grid power to convert the direct current in the battery to alternating current; you cannot use your solar battery if there is a power outage!
• It takes a while to charge a large solar battery; this is not the case with an MNR due to its smaller capacity