Here's my equipment...what can I do???

I guess you are in the Netherlands? Your system is relatively small. Many times is it worth the costs (building permits, labor, etc.) to properly "connect" for GT Tied solar power plan. And many utilities/locations may not allow GT solar connections anyway.

Assuming you 1,400 kWH per day, and that nominal cost of power in Netherlands is ~Eu 0.20 per kWH:

• 1,400 kWH per year * Eu 0.20 per kWH = $280 per year

And you have 3x 12 volt @ 100 AH automotive GEL batteries. GEL batteries are typically used for standby applications (float, then supply high power for 30 minutes to allow for a power outage/recovering/genset start to take on loads longer term/etc.). 

You need to look at the cycle life of those batteries (car batteries are not usually deep cycle design) which may be in the 100-500 Cycle range (if you pull them below ~85% State of Charge (all examples/guesses as to how "your batteries" will behave).

For example, if you cycle them below 85% every night, that is ~365 cycles in 1 year... Or you have to replace those batteries once a year (2 year life for "standby" GEL in UPS applications is pretty standard).

So--What would be the cost of replacing your batteries every 1-2 years (>$280 in energy saved)?

And there is the question of your operation with a GT Capable (?) hybrid AC inverter... Since you have had "no issues" in the last 4 years (no knocks from a utility worker asking about your system), I assume that everything is working (if not 100% legal).

What happens when you generate/backfeed energy to your home panel... When solar power is less than your loads, you are slowing down the meter and using your power during the day--Which is saving you actual money.

When the solar power exceeds your local loads, one of three things may happen (and this depends on your utility meter configuration by your utility).

1. Meter spins "forward" when you consume power (normal operation)
2. Meter spins "backwards" when you generator power back to the utility (in decades past, utility meters worked this way) And you actually put money "in the bank" (generate power daytime, consume power at night). If this is your setup, just about perfect.
3. Meter does not spin backwards... If your solar power exceeds your loads, the "excess" power is "lost" to you and give "for free" to the utility. Not great, but for a small system like this, your daytime loads may exceed your solar output much of the time--So not much money is "lost" to you.
4. Meter spins forwards if you consume or generator excess energy. New meters (at least in the US) are doing this more and more. This is branded as "revenue" guard. Some folks have been known to install their meter "upside down" for a week or two a month. And when the meter turns backwards, it reduces their bill by a lot. With "revenue guard", the meter spins forwards no matter the direction of energy flow. With GT Solar, this means your "donation" of energy to the utility actually shows up on your energy bill as if you consumed this power....
5. Meter phones home when GT solar is detected. Some utilities have worked/programmed their computers to find guerilla solar installations. And in the USA, the utility can pull your meter and the local city can red-tag your home. I have not read of this happening to anyway, but is is in our laws.

On a sunny day, with few loads, see if your meter is spinning forwards or backwards or stopped (turn on/off your loads and GT inverter--See what happens)... And see what is actually going on with your meter... Mechanical meters tend to be bi-directional or one way. Electronic meters can be programmed to do just about anything the utility wants.

-Bill