Choosing battery storage for our Fronius system

[Keith123456]

We currently have the following

1. Fronius Symo 12.5-3-M - connected to 36 LG 340W solar panels shared between the roof and a few on a south facing wall
2. Fronius Symo Hybrid 5.0-3-S - connected to 22 LG 340W solar panels on the same south facing wall

Our electricity usage is highest outside sunlight hours, therefore to get maximum impact from our panels we will have to invest (heavily) in batteries and / or heating elements for our hot water.

Unfortunately our 'solar energy' electrician seems to be learning on the job, so our trust is quickly dwindling. I'm sure I'll have further questions but these are currently badgering me.

1. I was thinking of getting x2 LG Chem 10 Lithium batteries as they are compatible with the symo hybrid. Would these have a maximum 'upload' of 5kWh or 10kWh our electrician was on about AC 5 and DC 5 but this is where it all got cloudy for me.

2. How do the LG Chem batteries compare to the Fronius storage system ( looking at the 4.5kw system) which appears to be double the price....?

3. As the feed-in tariff is shocking here in Austria - (fixed €0.029) we need to utilise all solar energy, therefore the plumber / electrician have suggested a 9.8kWh 1000l hot water system, what would be the pros / cons of such a system as I really feel I don't have a clear picture anymore

thanks in advance
Keith

[Ampster]

1. I was thinking of getting x2 LG Chem 10 Lithium batteries as they are compatible with the symo hybrid. Would these have a maximum 'upload' of 5kWh or 10kWh our electrician was on about AC 5 and DC 5 but this is where it all got cloudy for me.

The specs may be different in your country. I would check the LG Chem website for details. They may also have a list of installers that have more experience than your guy. I am only suggesting that for just the battery install. It takes some knowledge and experience in the cases I have seen them installed. There maybe a special interface board that might be needed.

2. How do the LG Chem batteries compare to the Fronius storage system ( looking at the 4.5kw system) which appears to be double the price....?

LG Chem is one of the largest battery manufacturers in the world. As far as I know Fronius is primarily an inverter company that probably sub contracts out the battery business. The best way to compare prices is to use the same capacity in kWhrs or if that is not possible divide cost by capacity to get a price per kilo Watthour of storage.

3. As the feed-in tariff is shocking here in Austria - (fixed €0.029) we need to utilise all solar energy, therefore the plumber / electrician have suggested a 9.8kWh 1000l hot water system, what would be the pros / cons of such a system as I really feel I don't have a clear picture anymore.

If you are talking about electric water heating I would look at heat pump technology. Initial cost is higher than simple resistive heat but operating costs are a lot less so in the long run you pay less.

[bcroe]

If you are trying to heat electrically, heat pumps are the way to go. My inverter driven compressor
heat pumps are 4 times as efficient as resistive heat. Not sure how efficient pump water heaters
are today, but you had best do all your water heating under the sun and take the load (and losses)
off battery. I have been able to use hot water for several days after the heater was turned off.
Bruce Roe