In our ever increasing bid to be green we are now the proud owners of a 4kW Solar array and a 5.8kWh battery. The panels themselves were installed last week. Steve and Dan from Pure Electrics were here today to wire everything up, install the battery and the inverter and get it all up and running.
The solar panels took up more of our roof than we were expecting. We had 12 360W panels fitted, which is a total of 4.32kW. We can probably fit another 4 or 5 panels on in the future should the need arise which would allow us to increase our maximum generating capacity to around 5.7-6kW.
You can’t really see them from the road or the garden but I did sneak up the scaffolding to get a couple of photos of them over the weekend.
The roof faces directly south so they should be in the ideal position.
Battery and Inverter
With the panels on the roof the job today was to install the battery and the inverter. The battery is a 5.8KWh affair. The inverter converts the DC output of the panels into AC current that we can use. It also determines where the power is needed and directs it there.
The battery itself looks fairly nice in the office. Certainly no worse than the storage heater that was there before.
It even has some nice flashy lights on it to tell us how much charge it has and whether charge is being added or drained from it.
The inverter isn’t quite so pretty and the isolator switches next to it and the cable ducting around it look a little industrial. Fortunately it is behind the door so is never really seen. I guess if we felt the need we could get a cupboard constructed around it to hide it all away.
There are of course various ways these things can be set up. We’ve gone with what is probably a fairly standard set up.
When the solar panels are generating it will first be directed to whatever is using energy within the house. We always have the aquarium on and at least the 24/7 weather station computer. There are plenty of other things that are always on and drawing small amounts of power too. A fridge, a freezer, a fridge-freezer, several things on standby, the router, telephones, the water feature, the chargers for our three robots and such like all contribute to our background consumption. This means even if everything else is off we are constantly using about 0.2kW. Anything from the solar panels will go to that first. If we have more power-hungry appliances on such as the shower, washing machine etc then it’ll go to that as well. Essentially if there is enough power coming from the solar panels then it’ll get used by whatever we are doing first.
If there is more power being generated than we are using then it will next go to charging the battery. That will continue until the battery is fully charged At that point, if we have the car plugged in then any excess from the solar panels will go to the car.
Finally, if we are generating more than we are using, the battery is full and the car is either full or not plugged in then any surplus will then be fed back into the grid – we’re not set up to get paid for this yet though and we’re not sure if we can as we don’t have a smart meter and apparently we can’t have one fitted either.
So, the power from the solar panels will follow this hierarchy
Solar -> House Requirements -> Battery Charging -> Car Charging -> Export to Grid
As far as where our energy will come from this means that if we are using less than we are generating it will of course be coming from 100% self-generated solar power. If we are using more than we are generating then any further requirements will be drawn first from the battery and then from the grid.
So, at the moment a few hours after the installation it is pouring with rain and almost dark. The solar panels are barely generating anything (according to the display on the inverter just 90W). From what I can see, the house is using around 0.5kW, so quite a lot more than we are generating. The battery however has 39% charge so we should in theory be using power from that. I’m not completely convinced we are but I’m also not properly familiar with the various displays on the inverter yet.
It seems to be suggesting that the full 0.5kW is being drawn from the grid rather than the battery which isn’t what we want. But then again, the battery charge level has dropped a little which would suggest that power is being drawn from it as intended. I guess we’ll have to keep an eye on it and get used to the various screens. We’ll need some sunshine at some point too so that we can see if everything is working as we want.
We’ll also connect a wi-fi dongle to it soon so that we can monitor things on a app which might make it easier to understand.
It’s not going to change our world or save us huge amounts of money but every little helps.