Photovoltaics are coming up - Options: 19 kWp, 25 kWp, 30 kWp, Storage?

Good morning everyone,

we are planning to acquire photovoltaic systems and I have finally received a first offer. At the moment, everyone seems very busy; out of three requested providers, only one has responded after several weeks. Compared to the many threads here, it seems a bit expensive to me, but this is somewhat offset by the fact that it could theoretically be installed in April (depending on the module selection, see below).

I am aware of the fundamental discussion about storage or not; the offers have been made with a storage system for the time being.

The local conditions:
Flat roof with almost 230 sqm usable area, completely without shading.
Last year’s consumption: 12,800 kWh: 8,300 kWh heat pump meter, 4,500 kWh household meter
I recently got an electric car, for which I expect around 4,000 kWh annual demand
Expected yield: 900 kWh per kWp

Offered options:

Possible modules, same price with the same total performance:
Hyundai HiE-S410VG (only available again from May)
Solarwatt Classic H1.1 pure 375 (in stock at the provider)

Optional storage:
E3DC S10X 14 kWh
E3DC S10E Pro 19.5 kWh

Complete system offers (net!):
19.68 kWp - €22,828
+ 14 kWh storage €13,250
Opt. 19.5 kWh €18,630

24.6 kWp - €27,552
+ 14 kWh storage €13,250
Opt. 19.5 kWh €18,630

According to the provider, 30 kWp also fits on the roof, but then a ripple control receiver would be mandatory. Can be offered on request.

My questions:
- Are the offers still fair or overpriced?
- Does it make sense to take the available but somewhat “weaker” solarwatt modules? Considering the current situation, is “a bird in the hand better than two in the bush”?
- Is storage possibly still sensible with our comparatively high consumption and the low feed-in tariff? Probably not mathematically, but considering the current trend in the energy market at least an investment in independence and some peace of mind?
- Is a controllable wallbox (E3DC Connect) worthwhile? It is apparently included in the offer but not separately priced; I already have a CEE32 socket in the garage and charge with a Juice Booster up to 22 kW (missed the wallbox subsidy, so approved 22 instead of 11 kW by the network operator)

My line of thought: If I realize about 60% self-sufficiency with the storage, I save €2,380 per year at the current electricity costs of 31c/kWh, so the “small” system with 19.68 kWp and 14 kWh storage would be “paid off” in 18 years. Feed-in and maintenance costs are not considered here.

I find the photovoltaic offers very fair to cheap given the current market and also a quick implementation. However, I find the storage system very expensive at that price; it should be significantly cheaper if you want one. For example, look up the prices of the popular Byd storages online. If the storage price is also net, then all the more so.

Regarding the storage system: The offered storage is tendentially too large for the size of the offered photovoltaic system.

If the two modules are priced the same, then you are using less roof space for the final output. Therefore, clearly go with the better modules and possibly expand later. The statement about 30kWp is wrong; you can install up to 29.99kWp without any regulatory technology. If that fits, then build that according to your consumption. The question would be how much fits completely. You could a) calculate whether >30kWp makes sense despite the extra effort or b) install a larger inverter and expand the system after 13 months.

A storage system is worth it at best if you can reclaim the VAT (only possible with a complete purchase including photovoltaic, not as a retrofit) and can take advantage of funding (usually at the state level) and the price is right. Economically, a storage system will be worthwhile depending on further price developments at a purchase price of around €500/kWh after all deductions. You are far from that.

I cannot contribute anything regarding the wallbox. But that should not be overestimated, because when will your photovoltaic system deliver >22kW? With your current offers, never; with 30kWp, only on a few sunny days in midsummer at midday.

PS: I myself have 28.35kWp (east/west) and 10.2kWh storage.

8300 kWh heat pump meter

What kind of house are you heating with that? Sounds at first like poor insulation, huge house, or poorly adjusted heat pump.

What kind of house are you heating with that? Sounds at first like poor insulation, a huge house, or a poorly adjusted heat pump.

250 sqm flat-roof bungalow, monolithic construction (36.5 cm Poroton) with an open inner courtyard, so lots of external walls and window surfaces (e.g. 5x 5m lift-and-slide door). With hot water circulation. It also doesn’t help that my wife insists on taking hot baths 3-4 times a week :rolleyes:

I find the photovoltaic offers very fair to cheap given the current market and also a quick implementation. However, I find the storage very expensive at that price; it should (if you want one) be significantly cheaper. For example, have a look at what the popular Byd storages cost online. If the storage price is also net, then even more so.

On the subject of storage: The offered storage is tendentially too large for the size of the offered photovoltaic system.

If the two modules have the same price, then you actually cover less roof area for the final output. So clearly the better modules and possibly expand later. The statement about 30kWp is wrong; you can cover up to 29.99 kWp without any regulatory technology. If that fits, then build that according to your consumption. The question would be, how much can fit completely? You could a) calculate whether >30kWp makes sense despite the extra effort or b) install a bigger inverter and expand the system after 13 months.

A storage only "pays off" at best if you can reclaim the VAT (only possible with a complete photovoltaic purchase, not with retrofitting) and can also take advantage of a subsidy (usually on a state level) and the price is right. Economically, a storage will be worthwhile depending on further price development at a purchase price of around €500/kWh after all deductions. You are far from that.

I cannot contribute anything about the wallbox. But that should not be overestimated, because when will your photovoltaic deliver >22 kW? With your current offers never, with 30kWp on a few sunny days in midsummer around noon.

PS: I myself have 28.35 kWp (East/West) and 10.2 kWh storage.

Thanks for the feedback. So tendentially rather towards maximum power on the roof area.

Normally I charge the car with the lowest power I can set (about 2.6 kW) as it’s gentler on the battery, but I can regulate up to 22 kW if it needs to go faster.

250 sqm flat-roof bungalow, monolithic construction (36.5 Poroton) with open courtyard, so many exterior walls and window areas (e.g. 5x 5m lift-and-slide door). With hot water recirculation. It doesn’t help that my wife thinks she has to take a hot bath 3-4 times a week :rolleyes:

36.5 Poroton sounds like a fairly new build. Then the heat pump consumption is still way too high. Normally it would be about 4000, at most 5000 kWh heating per year. Which heat pump do you have? Off to the piggy-pink forum with you :-)

Good morning everyone,

Morning.

A few things upfront: There is no limit at 30 kWp. You should always fully utilize a roof. Systems are getting cheaper and with your consumption, 100 kWp is still too small.
You need a ripple control receiver starting from 25 kWp, but it doesn't hurt (apart from the one-time 300,- Euro cost that most of them have). Nothing is curtailed because of it.

If the house connection only allows 30 kVA, you can easily install 40 kWp on the flat roof and limit the inverter to 30 kVA. If you talk to the right people, the grid providers know this too. You basically have no losses with that, since the flat roof can never reach the maximum power anyway.

Also important for the flat roof: You should always tilt about 15°. Something like this: /\/\/\. Some facing east, others facing west. If it fits better in terms of space requirements, north-south also works. The yields are roughly the same. Why do this? From 15° on, there is no longer a need to clean the modules. If you lay them completely flat, leave walkways free and really go up once a year with a scrubber and garden hose!

SolarEdge is always too expensive and practically never necessary. In your case, definitely not necessary. The inverters are anyway way too small.

The prices you mentioned for the modules are fair. Storage becomes economical from about 250,-€ per kWh.

With your consumption and the planned system size, you achieve 50% self-sufficiency even without storage. (Payback without storage is about 10 years.) The more consumption you have, the less it pays off. If you then also have a controllable large consumer (heat pump and e-car), it pays off even later. So just leave it.

E-car charging: The smaller the output, the higher the charging losses. So I would charge with at least 6-11 kW. Most models' batteries can handle even 50 and more, so you are still far from anything that could damage the battery. A controllable wallbox is mainly a comfort feature. Plug in in the evening, charging ends when the sun goes down, starts again when it rises. I find it practical. With a bit of running around, you can of course achieve similar results.