We are building our own self-build house in the UK and part of it is 7.6kw solar PV array (separated into two strings). The panels are due to be installed on our roof next week and then when our house is a bit further along (and after we have received our G99 back) we will install the batteries and inverter. We have sourced the PV panels already. My electrician and his colleague who owns a solar PV renewables company who is MCS certified will be installing all of our equipment.
We are on single phase 100A mains electricity. We would like to have battery storage such as 4 or 5 Pylontech US5000 to begin with, as I know battery capacity is crucial. I was initially looking at a hybrid inverter which will do everything for us, such as a grid-tied Solis 6kw hybrid inverter with EPS backup. It apparently allows up to 100A and 5kw continuous discharge current in event of a powercut (or at night time) which I believe means we are not limited to small critical loads only during the evening or a powercut?
What we would like to do is charge our batteries over night on off-peak grid mains (so the inverter needs to have a good charge rate) and during the day charge up too directly from the solar PV. We are going to be running an ASHP (but we have solar thermal going in too so it won't be used that often). Our aim is to be able to run most of our appliances during the day and crucially also during the evening and in event of a powercut (assuming we have enough battery storage). So the inverter (and combined battery modules) needs a good discharge rate too and seamless EPS changeover. So we need a grid-tied inverter which can also work off-grid.
We don't want to be restricted to running only small essential critical loads only during the evening/event of powercut. In summary we want a solution which, in the event of a powercut (or at evening when there is no sun), is seamless changeover. I assume 5kw would suffice (from the Solis hybrid inverter). From what I can ready the Pylontech US5000 have a continuous discharge rate of 80A (although some people say it is just 50A..which is confusing, although I assume 50A would still be fine for average household loads - although our heat pump will require a 25amp breaker, the heat pump controller will require a 16amp breaker and the hot water cylinder/immersion will require a 16amp breaker, so a total of 57amps so we may struggle during the evening or event of powercut when running solely off batteries?), and if more than two modules would have a combined discharge rate of 4.8kwh (I think). So I am guessing in order to run our average household loads during evening or event of powercut we will need a good amperage and kw discharge rate (from the inverter/combined batteries).
I am assuming the Solis 6kw hybrid inverter do the job for what we need. Not sure about the Pylontech US5000 batteries due to the low amperage available. Should I be looking at higher voltage batteries instead of these?
I have also been recommended I look at Victron too, as an alternative to a hybrid Solis inverter. However I know the Victron solutions work slightly differently - ie you have a solar charger and a battery inverter and Victron don't do an "all-in-one" hybrid inverter. So ultimately I will need two inverters in total from what I understand and also two separate MPPT units to handle our two PV strings. Or are the MPPT units acting as the "solar chargers" and to go with this I need a battery inverter (such as Quattro or Multiplus II)?
I am a little confused as to what items of equipment I would need in order to fulfill our requirements (mentioned above). I know Victron might be slightly more expensive but I want to be able to look at all options because I want a solution which will be reliable for many years and I know Victron is one of the best around (plus I like tech things). I understand some of the Victron inverters (which are grid tied as well as off-grid), are not G99 certified. We need a relatively simple solution, ideally to keep cost low too, and it has to be able to handle an input of around 8kw pv and ideally be acceptable by SSE, our DNO for single phase (ie our G99 application).
Sorry for the questions. I have searched extensively on this and spoken to a few helpful people online but to be honest I am still slightly confused with what items I might need in a Victron solution to meet my requirements. Please can anyone help?
Thank you very much for any help.