ᐅ New photovoltaic system with storage in a single-family house – experiences

Good luck with implementing your plan. With a primary energy demand of 88 kWh/m² (8.2 kWh/sq ft) and a final energy demand of 48 kWh/m² (4.5 kWh/sq ft), it won’t add up, even with a wood stove. It won’t be cost-effective, and ambiance was not part of the discussion and cannot be measured.

berny schrieb:
That’s why I’m also building a house with < 20 kWh/m²/year, and in winter we’ll just use the fireplace

I hope your plan takes that into account. Especially as you get older, it can become difficult to source, store, stack, and bring in the wood. Unfortunately, wood is no longer cheap either—ready-split firewood, preferably pre-dried, can be quite expensive. At that point, the few extra cents for electricity don’t really matter anymore.

@hagaense: Thanks for the tip about the Volksbank NRW website; they really have a very good overview of batteries.
@Wastl: That’s exactly the plan: staying fit and getting old by building with wood myself in the forest (very close by); it might seem like my grandfather’s way for a long time. This won’t be a burden for me, but a pleasure...

berny schrieb:
Hello everyone, has anyone already installed a photovoltaic system with storage? If yes: How long have you had it, which brand, and what are your experiences? Is anyone (like me) planning to install such a system soon? Considering the continually declining feed-in tariffs, it seems worth reconsidering. What basic data are you using for your calculations? Thanks for concrete answers!

Hi,

yes. Since 04/07/2016.
An SMA Sunny Boy 5000 Smart Energy with a 2kWh (2.1 kWh) battery.

East/West orientation. Peak 6.625 kW. East 11 modules at 265 W heat pump, West 14 modules (Solar-World).

My experience so far is good, although we had spring/summer.... From late October to February at the latest, the system probably won’t generate much.

So far:
- about 1 kWh grid consumption per day
- 85% self-sufficiency
- Of the solar power consumed in the house, the battery supplies 30%! It is noticeable that even in bad weather conditions with very low yields, the battery still manages to charge somehow and the 2kWh (2.1 kWh) capacity is used. The best case was almost 4 kWh (4.2 kWh) per day through multiple charge/discharge cycles. Really good!

The battery is not economically worthwhile – currently, it’s a technical experiment, a world view, a hobby, call it what you like. I can only run the numbers in a year, but I estimate the battery costs me about 20 per month more than before.

The solution with the small battery definitely increases autonomy a lot. And it satisfies my urge to experiment as well as my pleasure in buying as little coal-generated power as possible. Just my opinion, nothing more.

Also, the system has helped me optimize my electricity consumption further. At idle during the night with ventilation and so on, I’m now at 175 Wh (earlier 245)! Daily consumption around 6-8 kWh (cooking, washing, dishwasher, TV,...). Last year it was over 15 kWh per day, sometimes 18. Now in summer: no problem. Not so in winter.

Regards,
Thorsten

Hello Thorsten, thanks for your reply. It looks quite good so far, despite the relatively small battery. I see it the same way: you definitely won’t get richer with a battery, but you should minimize purchasing coal or nuclear power. Otherwise, the description could have come from me as well: it definitely already contributes a lot in terms of self-sufficiency and satisfies my enthusiasm for experimenting. Just a quick question: what kind of heating and hot water system does the house have? Probably not a heat pump, right?

Best regards, Bernd

You have already heard several times that batteries are not currently worth it.
Whether the future will bring more improvements remains to be seen. Tesla entered the market last year with the Powerwall and plans to produce it in mass quantities. Other manufacturers are on a similar path. This could lead to a drop in prices—or not.

berny schrieb:
Interest rates for money in the bank are almost nonexistent now, so we simply avoid taking out loans and prefer to invest in an (energy) cost-efficient future.

Are you currently building or have you just recently purchased?
I’m just wondering because you mention that your money in the bank barely earns anything.
Mine doesn’t either—after building the house, aside from the reserves, it’s also gone from there.
What I mean is: those who install photovoltaic (PV) systems on their roofs usually have to finance them, since equity has already gone into the house. The interest on that financing must be earned by the PV system itself. This further delays the break-even point for purchasing a battery.

berny schrieb:
Also, everyone here in the forum apparently still benefits from the relatively high feed-in tariffs so far, but those will be quite low in the future—around 12 cents per kWh—and likely to decrease even more later.

I think most of the people posting here receive between €0.12 and €0.13 per kWh.
We are currently feeding in power at €0.1275 (as of August 2014).
At the moment, we do not run our geothermal heat pump directly from the PV system; instead, we use the heat pump electricity separately. Last year, our heat consumption was just under 3,500 kWh (KfW70 standard according to the 2009 Energy Saving Ordinance). Unfortunately, during the times of highest consumption, there is hardly enough sunlight.

By the way: this year was worse in every month except January and February in terms of production compared to the same period in 2015. Even the record August is likely to result in 20 to 30 kWh less feed-in. We’ll see how much September and October can make up for this. According to the weather forecast, it should at least start off positively.