Under loading the generator is a concern you need to address. You need to figure out how many watts you will be needing, an Energy Budget, and get a system that works with that load/budget. Too much generator is bad as is too little. You need a Goldilocks solution/generator.
If you have Internet access, having the systems in the cloud would likely be cheaper than having to burn the diesel to run a generator to power the systems in house.
What you are trying to do is what cruising boats do all of the time. They have power loads, ironically called house loads, that are almost always powered from batteries. The batteries are charged via alternators on engines, generators, solar, winder generators, and/or hydro generators.
The big consumers of power in a house or a boat are HVAC(Usually AC), fridges, freezers, and hot water makers. Working within an energy budget, which is what one does if not grid connected, means you best bang for the buck is to minimize energy requirements. What you don't want to do is run a generator anymore than is required to generate power due to cost.
Solar power is a rich mans game in that it cost quite a bit of money up front for the installation. However, there are Federal, and sometimes state, tax rebates that will pay back a good percentage of the installation cost. The problem is that you have to have the money upfront, and depending on the state incentives, have the financial ability to wait for years to get the full rebate. The last time I checked, between the NC and Federal tax rebates, I would get 65% of the cost of the solar installation paid back to me. But I would have to have about $20,000 upfront and it would then take a few years for all of the state rebate to be paid. My system would not have batteries...
Batteries are the real Oh Scat in off grid systems, be it a house or a boat. Lead acid batteries are a consumable. An expensive consumable. You will use them up, they will have to be replaced and if you get 10 years out of them, that would be amazing. Lead acid batteries should not be used so that more than 30% of the energy in the battery bank is used. Using more than 30% of the power starts to dramatically reduce the number of cycles/lifetime of the battery which increases long term costs. What this means is that once you figure out you how many watts/amp hours you need each day, you have to triple the size of the battery bank. :shocked: Taint cheap but it is worse. If one is depending on solar or wind to power the battery bank, then the battery bank needs to be even larger to cover the time when there is no sun or wind. :shocked::shocked::shocked:
So one might say, well use a generator to fill up the battery! Well, that will be expensive because one of the problems with lead acid batteries is Partial State of Charge(PSOC). Lead acid batteries self regulate how much power they will take as they become charges, say around 80% filled. At that point, they started taking less power, and depending on the size of the battery bank, it can take many hours to FULLY charge the batteries. If one is using a generator to fill up the batteries, the generator will be producing very little power because the batteries are not asking for power, and the generator will be under loaded... :confused2:
The best way to fully charge lead acid batteries, ie, get that last 20ish% into the batteries is with solar or wind. But to do that, the solar and/or wind power producing system has to be designed with the size of the battery bank.
Lithium batteries don't have the problems of lead acid but one REALLY has to pay attention to the various Lithium battery chemistry. The information I have read about Tesla's wall batteries does not mention which Lithium chemistry they are using which is critical. The fact they do NOT mention the chemistry to me is a big red warning flag. Another problem with Tesla's wall battery is that is only warranted if one is using solar and maybe wind to charge the battery. Grid or generator charging nullifies the warranty.
:shocked:
The best Lithium battery is LiFePo chemistry. These batteries do not explode nor catch on fire like other Lithium chemistry batteries. They do not have the PSOC problem of lead acid, they can be charged with a huge amount of power in a short period of time and can also provide a higher amount of power out of the battery compared to lead acid. Roughly twice the power in and power out vs lead acid. Even better, the batteries can be used so that up to about 80% of the battery capacity without too much of a life reduction. However, using about 50% of the battery capacity seems to be a good balance between lifetime and battery bank size/cost. Yet another advantage of LiFePo is that as the power is used of voltage remains pretty constant unlike lead acid. LiFePo batteries are also about half the weight and size of lead acid and because there is more power available with LiFePo, one can have a much smaller and lighter battery bank.
Soooo, since LiFePo batteries are soooo much better than lead acid why aren't they being used? One word. Cost. They are much more expensive than lead acid on an upfront comparison. However, even with the high prices, their long term costs seem much cheaper than lead acid. But the price to buy is easily $10,000+ depending on the size of the battery bank.
Circling back to the proper loading of the generator, it is easy to miss one important fact in what I just said. LiFePo batteries can accept huge amounts of power in a short tme which means you can design a battery bank to power your loads/Energy Budget for N number of days, which then allows one to size the generator so it only needs to run X number of hours at a given load Y, where Y is going to provide a load that will maximize the life of the genset.
Later,
Dan
