House that is almost energy independent, and is designed for a temperate climate. And some musings on ammonia and nuclear power.

I noticed that photovoltaics are really cheap now. 27 kW of peak power would cost around 30 000 PLN (1 USD is equal to 3.65 PLN when I am writing this). Array of 60 of those, with peak power of 475 W each, which actually will be closer to 450 W, because of marketing and degradation progressing with time, would cost under 30 000 PLN now.

I was actually thinking about array of 4 rows and 12 columns of 1757 × 1134 mm panels, that are mounted on a south facing side of a gable roof with a 45° pitch. Four places in this array are empty, because of windows that are to be mounted there. Ideally PV panels would track the sun, but in winter sun changes position in the sky only slightly, and pointing photovoltaics directly at it is not a bright idea, because much of the light received is diffused, and comes from around the sun, and rather not from below the horizon.

30 kWh of LiFePO4 batteries would cost 14 000 PLN. This would be enough to provide 12 kWh of electricity during most of the days, even during Polish winters. I am assuming that only 60% of maximum batteries capacity is used (overcharging and deep discharges are bad for batteries). I would like to add that if all of the lithium produced during a year was to be converted into LiFePO4 batteries, and then all of them would be distributed equally among all humans, everyone would get only around 0.3 kWh of them. So per a member of 4-person household 25 years of lithium production would be required.

The real problem however is heating of home during winter. My idea for solving this is using electricity that cannot be stored in batteries during sunny winter weather to power cheap air source heat pumps to increase temperature of a "swimming pool", that is actually a thermal energy reservoir consisting of 50 tons of water. Reservoir is slightly insulated from the rest of the building. Five heat pumps with COP of 4,15 and maximum heating power of 16 kW at A7/W55 costing 7000 PLN each would suffice to fully take advantage of winter sun.

In the case of a southern Poland, during an average December day, 15.7 kWh of power would not be stored or directly consumed as electricity. This could be used to make approximately 60 kWh of heat. Well insulated building with recuperators, and possibly ground-coupled heat exchanger , could probably keep a decedent temperature inside with that kind of heating, although keeping everyone comfortable would require additional energy from the outside.

When it comes to producing domestic hot water, I would like to use waste heat from water-cooled energy demanding electronics, such as CPUs and GPUs, to generate heat required. Refrigerator (which basically is a heat pump) could lower temperature of electronic components, while increasing temperature of utility water. Additional source of heating might sometimes be required (extra heat pump for instance). If tank with utility hot water gets too hot during winter, it could transfer heat to the "swimming pool".

Large heat pumps and "swimming pool" could be used to keep interior of the house cool during summer.

I would like to add, that I think that breeder reactors are better energy sources. They are not intermittent, so production of hydrogen and ammonia would be much cheaper. I dream of a transportation that is ammonia based. 1 trillion (10^12) PLN would be required to build installations producing 1 EJ (10^18 joules) of chemical energy that can be released during combustion of ammonia over all year, which is the amount required to power all road vehicles. Approximately 100 GW would be required to keep this operation continuously ruining. So if 1 GW of power from nuclear power could be kept below 5 billion (10^9), 1 kWh of ammonia would cost as much as oil. Intermittent solar power would increase this cost twice.

I will probably add illustrations and additional information in the future.