Thanks for the responses, I wanted to get into the deeper parts after the small introduction
We live in Uruguay and we´re a blessed with a lot of sun and a lot of incompetent professionals So I might end up doing it myself, even though I would prefer a professional installer.
I also had to wire the house myself, after talking with some of these "professionals".
The primary reasons for installing solar system is unreliable power from the grid. The power is usually out for 15 minutes and sometimes for a few hours, a couple of days ago we were without power for about 5 hours. There may also be fluctuations in the voltage. So the system needs to work sort of like power stabilizer and UPS.
The secondary reason is to be able to "survive", without grid-power for extended periods of time. Which means keeping the combined freezer/fridge running, heating a bit of water, having a bit of light, washing clothes. We have a big solar oven and a wood fired oven for heating/cooking, so that saves some energy.
We expect to get most of the consumed energy from the solar system, but would like the convenience of having the grid as a backup.
We don´t expect the solar system to be able to pay for itself, but probably everything besides the batteries. We pay about 0.2 USD/kWh.
We would like to keep maintenance low, keep the batteries inside the house (close to the inverter) and as mentioned it should work like an UPS.
So far I think this points in the direction of deep cycle AGM or lithium and a suitable hybrid inverter.
If we buy deep cycle AGM, then we have to consider that they are not as good at deep discharging, so we would have to buy more battery capacity to compensate for that. Further I don´t think there are any really good quality AGM here. Lithium Ion is a bit more than double the price of AGM. All in all I think they economically end up somewhere in the same ballpark. So that makes me look at other factors.
Lithium Ion has a higher roundtrip efficiency, can better utilize the stored energy at various loads and can charge/discharge faster, which should translate into better utilization of the collected energy and a better user experience. So this tips me in favor of lithium ion.
We have very limited options in regards to what we can buy here in Uruguay, haven´t seen Victron, but I can get a GroWatt 5000W hybrid inverter, that delivers 5000W and can receive maximum 8000W of solar power. I can buy Everexceed and Weco lithium batteries, with decent cycle life and warranty, but there are not many reviews about them. I can buy some good JA Solar panels with about 19% efficiency.
We have sun most days, most of the year, usually cloud free or very few clouds. According to WeatherSpark.com, the darkest day of the year has 2.5 kWh per squaremeter a day and 7.8 kWh/sqm/day at the day with the most light, but WeatherSpark.com significantly overexaggerate the amount of clouds we have. It seems that sometimes the end of winter can be cloudy and rainy.
The highest point of the sun in the summertime is about 85 degrees and about 35 degrees in the winter time. We live in the southern hemisphere, so the sun is coming from the north. I figure we would get more stable output from the panels by angling them more towards the winter sun and after doing some calculations, it seems like 45 degrees fit the bill very well.
If match our consumption with the production we could have in June, when the sun is at it´s lowest, I end up with a need of about 25 m2 of panels at 19% efficiency, which is roughly 5kW. I guesstimated and subtracted a loss of 15% in the system, if I use an efficient inverter, short cable run and lithium-ion. To be on the safe side (dirt, variation in quality of panels e.t.c.), I think 6kW is suitable?
We would like to mount the solar panels on the roof of the porch, which is about 28 m2 and is facing north (slightly tilted, I think 5 degrees).
We would like the system to discharge max 60% and then switch to grid power, but have the ability to discharge further in case of power outages. It would be ok if the emergency discharge was able to cover a couple of hours without sun, as we rarely have longer power outages than that, I consider to have a rated battery capacity for somewhere close to a days use.
We already have 3x6mm2 cable (about 4 meter long) that goes to the porch, that could be repurposed for transporting energy from the solar panels to the inverter. As far as I can see, you can transport the power at fairly high voltages to the Growatt inverter, 120V to 550V, so this should give an insignificant voltage drop in that cable. I would like to keep them in groups of just above 120V, not to run too much power through the panels and also to some degree avoid too many panels being slowed by a panel that is not performing well.
We have laws in Uruguay, I don´t think a lot of people use them for anything, so I feel free to do whatever I want ;-D
We do very rarely get golf-ball sized hail, but would probably figure it out in advance. They caused 3 half cm deep dents on the roof of my Hilux.
Any thoughts, corrections and suggestions are very much appreciated.