Self Consumption in residential systems

Transcription

1 Self Cnsumptin in residential systems Brad Bassett Sr. Applicatin Engineer Jan 27, 2017 San Dieg, CA

2 What is Self Cnsumptin? A direct grid tie system is where slar energy prduced, pwers the huse lads as limited self cnsumptin, and excess slar prductin is exprted back int the utility grid. This self cnsumptin happens nly while the lads are present at the same time as slar prductin. N energy is stred by the user fr use at anther time. Any pwer needed fr lads, abve what the slar is prducing, is drawn frm the utility. Self cnsumptin, als knwn as Selfsupply, is a system where sme f the slar energy prduced is stred n site fr use at anther time when slar prductin is less than the lads. Shuld it be called Self-cnsumptin r Self-supply?

3 What is Self Cnsumptin? The graph belw demnstrates a typical lad prfile fr a self cnsumptin strage system. Peak net charging f batteries cincides with midday peak slar prductin and discharge is frm 6:00-10:00 PM.

4 Why use Self Cnsumptin? Off grid The riginal slar self cnsumptin N utility grid available r cnnectin very expensive Often with generatr backup Net metering nt available There is utility service, but utility intercnnectin and net-metering r feed-in are nt available Lw feed-in tariff rates There is utility service, and intercnnectin is available, but feed-in tariff has lw payback rates Time f use rates, demand charges There is utility service, and intercnnectin is available, but electric rates are in a higher tier when drawing ver a specific energy use level, r higher time f use rates at certain parts f the day. Curtesy Aquin Energy

5 Types f Self Cnsumptin Off grid N cnnectin t the grid, r grid is nly used fr backup if the slar supply cannt keep up with the lads. Self cnsumptin with grid exprt Slar can recharge the battery during the day and when the battery is full and current lads are supplied, excess slar pwer can be exprted t the grid. Energy frm the battery can be used during peak use in the evening. Battery pwer can als be used t reduce demand charges at any time f the day. Self cnsumptin withut grid exprt Slar can recharge the battery during the day and when the battery is full it will supply current lads, but nt exprt t the grid. Energy frm the battery can be used t supply the lads at any time the slar cannt d s. When the battery is depleted, the lads will be supplied by grid pwer until the sun cmes up.

6 Types f Self Cnsumptin systems Primary self cnsumptin Where the slar and battery can supply pwer t lads n the main huse panel, but des nt feed back t the utility. The inverter is subject t grid tie anti-islanding limits. The inverter will supply bth the huse and backup lads panels when there is grid pwer available. If the inverter has the capability, it can als prvide backup pwer during a utility utage. A prtected lads sub-panel is required fr backup pwer in almst all cases. The system will supply pwer t nly the prtected lads panel during a utility utage. Secndary self cnsumptin supplies nly lads n a prtected lads panel. The inverter will supply the backup lads panel. The inverter will supply the main huse panel nly when there is unlimited grid tie feed-in. Same as a grid tie inverter. Supplies pwer t the prtected lads panel during a utility utage.

7 Primary self cnsumptin withut backup Primary self cnsumptin

8 Primary self cnsumptin with backup Primary self cnsumptin

9 Primary self cnsumptin AC cupled Primary self cnsumptin

10 Secndary self cnsumptin with backup Secndary self cnsumptin

11 Sizing fr self cnsumptin Strage Slar Batteries are the mst expensive cmpnent f the system. Minimize the size and cst fr the best ecnmics. Mst ften sized t pwer the lads fr ne daily cycle at the apprpriate depth f discharge. May require detailed time f day use data. Hard t size fr highly variable lad prfiles. Extra capacity may be included fr backup pwer. Mst ften sized t pwer the lads during the day and recharge the battery fr the daily average. If net metering r even a reduced feed-in tariff is available, a larger slar array may be ecnmical. A larger array will help prductin fr cludy days.

12 Inverters used fr primary self cnsumptin Inverters fr primary self cnsumptin StrEdge 7.6kW uses a high vltage battery ie: 350 VDC t 450 VDC. Can be grid tied withut strage. Can ptinally supply backup pwer t a sub-panel with ~2 sec transfer time. Limited t 5kW utput t backup system and requires an aut-transfrmer. Frnius, SMA, OutBack SkyBx & thers upcming in the future. They will mstly use a high vltage battery. SkyBx will likely cme in high vltage and 48 VDC versins. Sme third party integratrs use metering n secndary type inverters t give them primary type capability. Inverter integrated with the battery Enphase, Tesla 2.0. The Enphase has n backup capability. These are AC cupled t the slar grid tie inverter.

13 Grid Zer and Peak Lad Shaving Inverters used fr secndary self cnsumptin Grid Zer and Peak Lad Shaving mdes will try t prevent grid usage by pwering the lads with slar and/r battery until the battery is depleted. While the slar can supply sme pwer the lads, it will ffset the use f grid pwer. When the slar is nt able t fully pwer the lads, the inverter will use the battery t pwer the lads until the battery is depleted. The next day the slar will recharge the battery. If the lads are t large fr the inverter t pwer, it can draw n the grid t help pwer them. T make sure that the inverter des nt push any pwer back t the grid it will always draw sme small amunt (~1 A 240 VAC) frm the grid. This is cmplicated by measurements f Watts and VA and the pwer factr f the lads. OutBack Pwer GS A and FXR-A series inverters Schneider XWPlus inverters Sunny Island?

14 Offset and similar mdes Inverters used fr secndary self cnsumptin Offset, Grid Supprt, Enhanced AC Supprt r Lad Supprt VDC mdes wrk while there is still a cnnectin t the grid. In these mdes the inverter will use slar pwer t reduce the draw frm the grid fr lads n the prtected lads panel. It will nt ffset lads n the main panel. The inverter can add grid and inverter pwer tgether t pwer larger lads. These mdes will nt use battery pwer fr any lads unless there is a grid utage, and will keep the battery fully charged. OutBack Pwer GS A and FXR-A series inverters Schneider XWPlus and SW inverters Magnum MSH hybrid inverters Sunny Island?

15 Drp Grid and similar mdes Inverters used fr secndary self cnsumptin Drp grid, Mini-grid, HBX, Online mdes will discnnect the inverter frm the grid and run the lads ff grid using slar and battery pwer until the battery state f charge r vltage drps belw a setpint. At the lw charge r vltage setpint the inverter recnnects t the grid t pwer the lads and may charge the battery frm the grid r nt as it is setup t d. Lads are limited t the inverter capacity. OutBack Pwer GS A and FXR-A series inverters Schneider XWPlus and SW inverters Magnum MSH hybrid inverters (r external cntrls) Samlex EVO inverters AC cupling AC cupling des nt wrk with any f these mdes with these inverters. The pssible exceptin is the lder SMA setup, and that is n lnger supprted fr grid tie systems with the newest US- 40 Sunny By inverters. Future inverters include the MidNite B-17 Capabilities nt specified yet

16 Batteries used fr self cnsumptin Flded lead acid High maintenance, high self discharge, lw efficiency, hazardus gases and electrlyte. Lw t medium high cycle life. Pr chice fr grid tied standby backup systems. Valve regulated lead acid - VRLA AGM r gel; sealed lw maintenance, lw self discharge, gd efficiency, very lw gassing. Lw t medium high cycle life. Superir life in standby applicatins, up t 20 years. Carbn enhanced lead acid Nan-carbn and Ultra lead acid; in VRLA cnfiguratin, lw maintenance, lw self discharge, higher efficiency, gd partial state f charge life, and medium t high cycle life.

17 Batteries used fr self cnsumptin Lithium-ION NMC Nickel Manganese Cbalt Oxide; very lw maintenance, lw self discharge, high efficiency, high cycle life, ptentially hazardus in thermal runaway r in a fire. Available as UL listed high vltage systems. Mderately expensive but cming dwn in price due t extensive use in EV s. Lithium-ION LFP Lithium Irn Phsphate; very lw maintenance, lw self discharge, high efficiency, high cycle life, mre stable, thermal runaway is less likely. Mst expensive s far. Aquin (aka: Saltwater) Aqueus Hybrid In; n maintenance, high self discharge, lw rate charge and discharge, mderate efficiency, very high cycle life, cmpletely nn-txic and nn-hazardus, mderately expensive.

18 End f life ratings Batteries used fr self cnsumptin Lead batteries capacity drps rapidly nce they reach 80%, s that is cnsidered their end f life pint. Lithium batteries will slwly have reduced capacity withut any drp ff pint. End f life varies depending n the use, but 60% is cmmnly used by the manufacturers fr statinary systems. Aquin batteries drp faster after 70% capacity is reached and that is cnsidered their end f life. Temperature ratings Lead batteries can freeze if fully discharged, but will withstand -40 if fully charged. The capacity drps ff dramatically at lwer temperatures and life is severely shrtened by peratin at higher temperatures. Lithium battery capacity will nt be affected by temperature as much as lead r ther batteries. Hwever, their perating range can be limited t as wide as -4 F t 122 F r as narrw as 14 F t 113 F. Aquin batteries will perate dwn t 14 F with smewhat reduced capacity. They will perate at up t a daily average f 104 F withut shrtened life. Outdr ratings Lead and Aquin need enclsures. Lithium is ften rated fr utdrs, and this may be required by cde sn.

19 Brad Bassett x Thank yu!