Small photovoltaic system 2 KWp

That is not really worthwhile. The proportion of fixed costs is too high for such a small system. Installation, electrician, scaffolding, inverter – these costs are incurred anyway, and even if the inverter becomes a bit cheaper and the installation perhaps goes faster, the difference will not decrease proportionally to the system size. 2 kWp might be about 1.5 kW output at peak times. That is enough for own consumption but only in summer and only if you can use the appliances at noon and cook at noon – but not at the same time, because at 1500 W minus the base load in the house you are already over the limit with stove OR washing machine and have to buy electricity. From autumn until spring, it hardly covers the base load.

With a realistic 30% self-consumption and an optimistic 1000 kWh/kWp per year, that would be about 600 kWh saved. You save about 150 euros per year with the energy provider – please do the math yourself.

This does not mean that photovoltaics are not worthwhile. I have a system myself and after one year of operation and first bills, I can make some reliable statements about whether it pays off. Yes, it does if the system is as large as possible (but under 10 kWp; otherwise, unfavorable conditions apply) so that you still have enough reserves to convert as much as possible to electricity. Because feeding in is no longer worthwhile, but self-consumption more so. Increasing it is an art form and takes a while, but you can increase self-consumption with targeted measures without relying on storage systems, which unfortunately still do not pay off at all, not even approximately.

For example, we acquired an electric vehicle (Twizy), a split air conditioning system (heating during transitional seasons and cooling in summer), a domestic hot water heat pump instead of an instantaneous water heater is planned (next year), as well as app-controlled wireless sockets for perfect utilization of surplus production.

In the first year from Nov 13 to Nov 14 we took 1890 kWh from the energy provider; before that period it was still 3500. Still, of the 7367 kWh produced (7.28 kWp system), we only consumed about 1200 ourselves. That means we also used less electricity. Well, the Twizy and the air conditioner only came in October 14.

Accordingly, I would advise choosing the system as large as possible to have reserves for self-consumption and to make an energy consumption above the base load possible at all, and for as long as possible during the year (Nov/Dec/Jan still look very dark in this respect, because almost nothing comes in then). Better to take stronger modules if space is tight. Better to banish solar thermal to the facade, where it makes more sense anyway, instead of giving up roof space. Also mandatory: Inform yourself further here in the forum (technology! tax issues!!) and get many quotes – the guideline for prices is 1300-1400 euros per kWp – so with your system size, no 3000 euros! Possibly a bit more due to the higher proportion of fixed costs. But as said – better build somewhat larger, i.e. at least 4-5 kWp.

Hello Elina,

Thank you very much for the detailed reply. Since we are still in the preliminary planning, the scaffold would be standing anyway. Do you have any good companies in Lower Saxony that you can recommend?
Feel free to send them in a private message.
Thank you Xinette

If you buy at all, really consider getting a larger system for a few euros more. For at least 7kwp, it should be clearly under EUR 10,000 net (as an entrepreneur, you get the tax refunded by the tax office)!

@ Elina
Good company, they operate nationwide in Germany and we were also very satisfied with them.

I would also recommend a somewhat larger system to you. Otherwise, the fixed costs make the whole thing unprofitable. We also used the standing scaffolding of the plasterers immediately when building the photovoltaic system. Unfortunately, the decision in favor of photovoltaics came very late for us. Therefore, the roofer's scaffolding (higher up) was already gone, and we still had to pay extra for a one-sided scaffolding extension. We installed 5.5 kWp. I can’t say much about the achieved efficiency for self-consumption yet, as we just moved in about two weeks ago. Our idea was also to cover a larger portion of washing machine, dryer, dishwasher, and the individual permanent consumers (e.g., fridge/freezer) and only feed in "a little" electricity. Since I am not at home from 6:30 am to 7:30 pm, cooking is usually done in the evening, so this consumer can at most use the photovoltaic system on weekends. If you are planning new purchases, make sure that the devices are programmable. I assume your electricity consumption has generally decreased because you moved in with newer appliances and possibly also pay more conscious attention to low consumption. Regarding your Twiezy - I just googled it. Is the battery rental charged annually or monthly? I suspect it is annual because, in my opinion, monthly rental wouldn't be worthwhile anymore. You are right about the dark season. Here in December from the 1st to the 6th, we did not produce a single kW because it was permanently dark and the cloud layer seemed endless. Yesterday was the first day the sun shone. Unfortunately, my wife forgot to start the washing machine, which had already been prepared. Well - everything is still settling in.

@ F-pNo no, it's not the devices. We moved in here 2.5 years ago, and the two yearly statements I mentioned are both from here. One is from Nov 2012 to Nov 2013 and the other from Nov 2013 to Nov 2014. Nothing changed with the devices except for one thing: at the end of Nov 2013 we bought a new refrigerator, the A3+ instead of the previous A2+, but the new one is roughly twice as big and also consumes almost twice as much.

Our Twizy costs 40 euros per month for battery rental for 5000 km annually, it is also possible with 30 euros (2500 km annually). However, the Twizy is still worth it because a tank fill-up then costs less than one euro! If you drive more, it is even more worthwhile, but at first we didn’t know how much we would drive with it. We can increase the mileage at any time. Since the battery is rented, it will be replaced free of charge if something breaks or the capacity drops below 75%. Also, you can get a free tow if you run out of charge and there is no charging station nearby. We don’t pay taxes for the little one, insurance is 260 euros per year regardless of SF and mileage (flat rate).