Sizing Energy Storage Systems for Rural environments:
Overview
This blog will focus on using battery storage and solar for the rural user. The biggest difference from urban sizing is that in cities the infrastructure is shared, but in the country it is often the responsibility of the homeowner. These responsibilities include:
Propane tank, and usually a service
Water through pumping from wells, springs or streams
Waste management, through septic systems
Also, rural properties often have more space, out-buildings, ponds, irrigation needs, and other various usages, than their urban counterparts.
Moving water and waste for a rural homeowner is often the main reason they look at backing up their property. Pumps have high electrical surges and require special consideration when designing storage. The primary loads rural property owners typically want to back up and attach to their protected loads panel (PLP) are:
Well Pumps
Boost Pumps
Septic Pumps
Refrigerators
Freezers
Igniters for propane furnace, water heater(s) and stove
Some lights and electrical outlets
Other loads we see less frequently but that are becoming popular are:
Electric water heaters
Mini-split space heaters/coolers
While the trend to switch appliances from propane to electric is happening in rural areas, it is generally not done for back up reasons. Unlike the urban dwellers who rely on utility services for gas, rural dwellers do not need to worry about the utility turning off their propane service, and most propane systems do not have the earthquake shut offs found in natural gas distribution. Propane can be a great tool for short term backup since it can provide heating for water, food and space, with minimal additional electrical load. However, many of our customers are evaluating moving away from propane. In addition to costing more than twice as much as natural gas, new research is showing that while propane burns clean, obtaining it is very harmful to the environment (maybe even worse than the full cycle of burning coal). Our customers are moving to solar and storage to address these concerns.
Design:
Okay, so onto design. Many of the storage systems that are on the market today are, in my opinion, designed for the urban dweller. Often, blogs of other solar and storage companies recommend that if you have a well pump, a generator is a better solution, since their storage system cannot handle the pump. I think the real solution is a better storage system. To understand this, you need to understand “surge”. Surge is the amount of power it takes to start a motor (refrigerator, well pump, septic pump etc.). For example, while a 1 hp (horsepower) well pump may run at 1,000-watts, it can surge to more than 5,500-watts when it first starts up. Many of the less expensive storage systems on the market have a 5,000-watt inverter with a maximum of 7,000 surge watts available. When you add a refrigerator, lights, plugs and maybe a septic pump, these systems fall short. But there are systems on the market that can handle this surge, like Sonnen, or multiple batteries from Enphase and Tesla.
. When one of our rural Sonnen customers flushes her toilet, the 1.5 hp well pump, the 1 hp booster pump and the 1 hp septic pump can all kick on at the same time creating a surge of up to 15,000 watts – and the Sonnen system can handle this. Another customer of ours has a 1 hp well and an electric water heater that surges to 11,000 watts. Again, that’s not an issue for the Sonnen. It is important to take into consideration these surges when designing Energy Storage Systems (ESS). You can always conserve battery storage by taking a 10-minute shower instead of 15 minutes, but you will not be able to take a hot shower at all if your storage system does not have the capacity to handle the surge on your well or electric water heater. Summary Let me leave you with a few ideas when selecting a storage system. One concept we always like to consider with storage is future proofing. From time to time water wells may go dry and need to be drilled deeper, or homeowners convert propane appliances to electric ones, or maybe you are building a rental or additional out-buildings. Make sure any storage system you purchase today can handle your future needs. Also look at a complete backup plan and ensure it meets the desires of your household in an outage. If you have a propane hot water heater, make sure the igniter is on the backup system. And try to leave items off your PLP that could drain a battery in backup mode like a hot tub or pond pump. A well designed back-up plan can provide a rural dweller with peace of mind with our ever increasing outages from the utility. Take the time to explore your needs and find a designer/installer and products that can meet them.
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