I am an electrical engineer and received this project to design an off grid PV system ( I think also known as a stand alone system since the power grid is not involved). I have never done anything similar in my classes that had to do with solar panels and PV systems in general.
I would appreciate any guidance that you can give me regarding the basic steps or important calculations to calculate in order to get started with this designing. I have attached the project question to this email.
Thanks for your help, I just need guidance to get started since I have never ever heard of PV systems before in my life.
I appreciate your help
As noted on this web site, we cannot provide specific design information on any solar project due to limited time available to answer each question on a free site, and with any design there could be critical information we do not have that could affect the advice given. However, I always try to provide a direction for our readers when possible.
First, any off-grid system starts with identifying what electric loads are to be powered, and for how many hours per day. Your list of this equipment has some serious problems which need to be addressed before even starting to complete a solar design. For example, you list an electric stove which is almost never powered from a solar system due to high load, but it is OK to power a microwave oven since they only operate a few minutes.
You list running power tools each day, but make no mention of a well pump which we would expect to have on an off-grid rural installation.
You list a refrigerator as a constant 24 hour per day load, but refrigerators and freezers cycle on and off all day, so you need to find the daily kW-hour usage for your average room temperature to use and not an instantaneous watt value.
You list a solar array output of almost 5 kWhs per day per kW installed which is highly doubtful. This may be possible for peak summer sunny days, but this is not realistic for an average output per day. We typically see solar arrays producing only 50 to 70% of their “nameplate” ratings except for very brief periods of extreme cold sunny days, and blue sky noon summers days with mild temperatures. For off-grid designs, this is a critical factor since you have no grid to fall back on.
Your battery bank requirements are not realistic and must have come from somebody reading a book. For example, your daily energy loads total 8.9 kWh and you want 3 days of no-solar battery time with 50% discharge. This means the battery bank would need have a capacity of 53.4 kWh, which would require four (4) deep cycle 1200 amp-hr batteries @ 12 volts each in series, which would have a combined weight of 4,640 pounds and would cost over $10,000 just for the batteries, plus a pot load of shipping and un-loading costs.
Finally, there are serious electrical design considerations when designing any solar power system, and this is even more serious for an off-grid system. The National Electric Code has an entire Section 690 that addresses wire and fuse sizing for solar arrays and I strongly suggest that you either obtain the services of a solar designer that has experience with these systems or plan on taking several courses on the subject first.
Good luck, and be sure to include a good fire extinguisher with your installation if you do not follow my advice.