{"id":13572,"date":"2021-04-03T13:38:44","date_gmt":"2021-04-03T17:38:44","guid":{"rendered":"https:\/\/www.greenneedham.org\/blog\/?page_id=13572"},"modified":"2024-01-20T12:22:34","modified_gmt":"2024-01-20T17:22:34","slug":"battery-storage-adding-to-your-pv-system","status":"publish","type":"page","link":"https:\/\/www.greenneedham.org\/blog\/battery-storage-adding-to-your-pv-system\/","title":{"rendered":"Battery Storage: Adding to Your PV System"},"content":{"rendered":"

Reasons for Battery Storage<\/strong><\/h4>\n

Let’s explore the reasons why you may want to include battery storage with your solar PV system.\u00a0 First\"tesla<\/a> of all, you don’t\u00a0need\u00a0 <\/strong><\/em>battery storage to be able to operate your solar system when connected to the grid.\u00a0 When you generate more power than you need (e.g. sunny daytime when not at home), the excess power is exported to the utility grid where it becomes available to other grid customers.\u00a0 In Massachusetts, the utility pays you the same amount of money for that exported power as you pay when you draw from the grid.\u00a0 So your savings are not<\/em> \u00a0<\/strong>affected by whether or not you store the power in your home.<\/p>\n

The primary<\/em> \u00a0<\/strong>reason to have battery storage as part of your system in Massachusetts is the ability to keep your house powered during a blackout.<\/em><\/strong>\u00a0 (Note that battery storage can be utilized in solar systems that have centralized inverters and<\/em> <\/strong>systems using microinverters.) Even if the sun is shining during a blackout, the solar system can not<\/em> \u00a0<\/b>provide power to your home without<\/strong><\/em> a battery storage system.<\/p>\n

The second<\/strong><\/em> advantage of having storage is that you can earn money from Eversource by allowing them \"home<\/a>to use the stored energy in the battery during periods of high electrical demand on the grid (e.g. hot summer afternoon, cold winter day).\u00a0 Known as demand response<\/em><\/strong>, this interaction occurs without any intervention from you – it is enabled through your internet connection which allows Eversource to communicate with your battery storage controller.\u00a0 Demand response allows Eversource to use decentralized energy storage resources like batteries in homes and businesses to meet infrequent periods of peak demand.\u00a0 This reduces the need to construct more costly power plants or to call on expensive (and often very dirty) generation sources that are typically used only as a last resort in these peak demand situations.<\/p>\n

If you choose to take part in this program, you can earn roughly $1,000\/yr, depending on the size of the battery storage system.\u00a0 Eversource will not initiate a demand response request when prevailing weather conditions indicate a possibility of adverse weather (because this is when you would need the standby power available in case of a blackout).<\/p>\n

Battery System Availability<\/strong><\/h4>\n

Battery storage systems are available from most solar companies.\u00a0 The large battery manufacturers include Tesla, Enphase, Sonnen, Generac, Panasonic, and LG.\u00a0 The batteries utilize Lithium Ion chemistry, similar to the batteries in your laptop computer or an electric vehicle.\u00a0 A newer version of the Lithium Ion chemistry (LiFePO4) has no potential for overheating\/fire.\u00a0 But both chemistries have a long and safe track record when installed by trained contractors.<\/p>\n

Battery System Cost<\/strong><\/h4>\n

Battery storage can be expensive, depending on how much storage capacity you desire.\u00a0 Installed cost typically runs $1,000 – $1,500\/KWH of storage capacity.\u00a0 In a house where you want to maintain power for 24 hours to supply your important 110v. loads (lights, refrigerator, TV, computer, furnace, etc.), you will probably need around 10-15 KWH of storage, with a cost of $15,000 – $25,000.\u00a0 As of 2023, battery storage systems are eligible for the 30% Federal Tax Credit (the same as for a solar system), reducing the total cost to you.\u00a0 Zero interest loans for Battery Storage systems are available through the Mass Save Heat Loan Program<\/a>\u00a0(about 1\/2 way down the page under “Financing Options”).<\/p>\n

Fuel-power Generator Comparison<\/strong><\/h4>\n

A fuel-powered generator with automatic transfer controls to serve as a backup system typically costs around $10,000.\u00a0 At first glance that may seem significantly less expensive than a battery storage.\u00a0 \"home<\/a>But after you factor in the federal tax credit, savings from demand response and the fact that a battery system requires no maintenance, you will likely be close to breakeven between batteries and a generator.\u00a0 You can get real numbers for your particular application from your solar contractor.\u00a0 Also, Battery backup is \u201cclean\u201d and quiet compared to a generator.\u00a0 You can easily add battery storage to an existing solar system without costly modifications.<\/p>\n

Battery Life<\/strong><\/h4>\n

The batteries are typically warranted for 10 years, but this does vary by manufacturer.\u00a0 The battery bank capacity typically declines over time as the batteries age (e.g. 70% storage capacity after 10 years).<\/p>\n

Battery System Install Location<\/strong><\/h4>\n

The battery bank should be installed indoors<\/strong> <\/em>(e.g., basement, utility room, attached garage).\u00a0 Outdoor installations are not recommended unless there is no other option.\u00a0 In our climate, there is a loss of capacity during hot\/cold conditions and the battery life is likely to be shortened.\u00a0 The space required for the battery varies by manufacturer, but using Tesla as an example, their single 13 KWH module is 4\u2019H x 3\u2019W x 6\u201dD.\u00a0 Depending on the size of your house and the loads you want to carry on battery backup, you may need two modules.\u00a0 In this case, the second module is placed in front of the first for an overall depth of ~12\u201d.\u00a0 The modules are very heavy and are typically mounted against a wall on a solid floor. Recent changes to the Fire Codes include requirements for fire-rated enclosures around batteries in certain locations.\u00a0 Review this with your contractor.<\/p>\n

Shopping for a Battery System <\/strong><\/h4>\n

When you shop around for a solar system, you should definitely ask for a cost\/benefit analysis for adding storage.\u00a0 You may find that the convenience, reliability, and net-cost make it a \u201cno-brainer.\u201d\u00a0 You might want to look closely at the specifications of the battery systems that you are interested in —\u00a0 Tesla’s Powerwall spec sheet.<\/a> is an example of what to look for\/expect.<\/p>\n

Still have questions?<\/strong><\/h4>\n

Would you like to talk<\/strong> \u00a0<\/em>to someone knowledgeable about solar battery systems who is not<\/em> \u00a0<\/strong>a salesperson?\u00a0 A Green Needham Energy Coach can provide expert advice that is free from commercial bias (we\u2019re not trying to sell you something).\u00a0 We can meet with you in your home or over the phone to help answer your questions.<\/p>\n

What we can<\/u><\/em>\u00a0 do:<\/strong><\/p>\n