Greetings!!!
I have an assignment for school which involves notionally designing an off-grid power system. I've decided to add an element of realism by gearing it towards a very small local farm.
This farm has a stream situated about 80 meters below (vertically) the main house and fields. I'm toying with the idea of using solar panels to power the home, and using excess power to run a pump to raise the water the 80m. When there is a lack of sun, the water can flow through the motor and generate power. Basically pumped hydro storage.
I'm fairly certain pumped hydro will not be the most cost effective option. In the context of this assignment its irrelevant, as long as I make sure to note that it is less cost effective than batteries.
Currently I plan to evaluate a diesel generator as a back-up power source, unless the teacher specifies that maintaining a grid connection is permissible (Which I doubt, because it makes the assignment very easy). I figure the generator can be a bit undersized in the peak load department, and have the surge currents compensated for by a small battery bank.
Peak loads will be carefully controlled by inexpensive micro controllers and relays. Simple logic will shutdown water heaters, dryers, and ovens when the A/C wants to kick in, and restore them as feasible when surge currents pass. I don't have to actually design the logic, but I will emphasize that the system would have priority load shedding defined by the home owner.
There a few things I don't know anything about, and I'm betting someone (nsaspook, for one) would know quite a bit about.
1. What do batteries cost when you buy them in the quantity and type for an off-grid system? Are the prices similar to what I see for standard deep-cycle?
2. Cables? What do they cost? Aluminum or copper?
3. Are DC or universal motor water pumps available? Can I generate power with a universal motor? Or, better question, if I generate power with an induction motor, will the rectifier and inverter care that the current and voltage are out of phase? Should I add some sort of power factor correction?
4. Realistic peak loads on induction motors. So given a list of motor parameters I can calculate it, but I know the blower and compressor on an A/C are not so nicely labeled. Is there a good rule of thumb I can use?
I have an assignment for school which involves notionally designing an off-grid power system. I've decided to add an element of realism by gearing it towards a very small local farm.
This farm has a stream situated about 80 meters below (vertically) the main house and fields. I'm toying with the idea of using solar panels to power the home, and using excess power to run a pump to raise the water the 80m. When there is a lack of sun, the water can flow through the motor and generate power. Basically pumped hydro storage.
I'm fairly certain pumped hydro will not be the most cost effective option. In the context of this assignment its irrelevant, as long as I make sure to note that it is less cost effective than batteries.
Currently I plan to evaluate a diesel generator as a back-up power source, unless the teacher specifies that maintaining a grid connection is permissible (Which I doubt, because it makes the assignment very easy). I figure the generator can be a bit undersized in the peak load department, and have the surge currents compensated for by a small battery bank.
Peak loads will be carefully controlled by inexpensive micro controllers and relays. Simple logic will shutdown water heaters, dryers, and ovens when the A/C wants to kick in, and restore them as feasible when surge currents pass. I don't have to actually design the logic, but I will emphasize that the system would have priority load shedding defined by the home owner.
There a few things I don't know anything about, and I'm betting someone (nsaspook, for one) would know quite a bit about.
1. What do batteries cost when you buy them in the quantity and type for an off-grid system? Are the prices similar to what I see for standard deep-cycle?
2. Cables? What do they cost? Aluminum or copper?
3. Are DC or universal motor water pumps available? Can I generate power with a universal motor? Or, better question, if I generate power with an induction motor, will the rectifier and inverter care that the current and voltage are out of phase? Should I add some sort of power factor correction?
4. Realistic peak loads on induction motors. So given a list of motor parameters I can calculate it, but I know the blower and compressor on an A/C are not so nicely labeled. Is there a good rule of thumb I can use?