Ask a Renewable Energy Expert

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

I'm going to disagree with Bill on this one.  The off grid guys I know (through the Outback Power user forum) all pretty much use their systems to run well pumps, A/Cs (many are in warm climates), even large power tools.  The secret is in having an inverter sized large enough to handle the starting current.  And many have soft start motors that reduce the inrush current. Most off grid batteries can handle large surge currents as well, if they are sized appropriately.

Resistive loads for heat are a steady current draw on a battery and will quickly reduce your battery "fuel tank".  That's why the push to heat pumps and HP water heaters.  

In short, resistive loads are not a good choice if you want to live off grid, unless you have a large solar resource with a huge battery. 

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

------------------------------
Kat Friedrich
Editor in Chief
American Solar Energy Society
Monona WI
------------------------------

Thanks for your responses, everyone. 

I was going to recommend this book as a shelf book for the ASES office, but based on your comments, I think it may have technical issues. It seems to advocate for undersizing solar power systems and relying on utilities and generators more than I hear other people discussing. 

What are some other books that you think provide a better general overview that really gets into the nuts and bolts of how to install and design PV systems? 

As someone who is editing Solar Today, I want to be familiar with instructions for the process down to the nut/bolt level, even if I am not planning to ever install solar panels hands-on myself. 

Thank you,

Kat

------------------------------
Kat Friedrich
Editor in Chief
American Solar Energy Society
Monona WI

Original Message:
Sent: 05-14-2023 02:05 PM
From: Kat Friedrich
Subject: Are fossil fuels required if an off-grid home has resistive loads?

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

------------------------------
Kat Friedrich
Editor in Chief
American Solar Energy Society
Monona WI
------------------------------

Thanks for your responses, everyone. 

I was going to recommend this book as a shelf book for the ASES office, but based on your comments, I think it may have technical issues. It seems to advocate for undersizing solar power systems and relying on utilities and generators more than I hear other people discussing. 

What are some other books that you think provide a better general overview that really gets into the nuts and bolts of how to install and design PV systems? 

As someone who is editing Solar Today, I want to be familiar with instructions for the process down to the nut/bolt level, even if I am not planning to ever install solar panels hands-on myself. 

Thank you,

Kat

------------------------------
Kat Friedrich
Editor in Chief
American Solar Energy Society
Monona WI

Original Message:
Sent: 05-14-2023 02:05 PM
From: Kat Friedrich
Subject: Are fossil fuels required if an off-grid home has resistive loads?

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

------------------------------
Kat Friedrich
Editor in Chief
American Solar Energy Society
Monona WI
------------------------------

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

I've had a remote Alaska off-grid facility for 27 years and consider resistive loads too demanding and inappropriate. I heat with wood when needed (only on site for March and summer) and have a supplementary propane space heater that is minimally operated. I have a 48v/1200 ah battery bank (16-600ah Sureties) and not had a need since 2014 to run any back up genset to charge the batteries. Each battery cycle rarely hits 25-30% drawdown. Avoid drawn down of 50% or more.  We have two 10 module azimuth tracing arrays for a total of 4.4kW. The trackers are not activated in March. Ample sun/diffused sun and albedo from the snowpack is ample for any electronics, shop equipment and kitchen appliances, LED lighting. 

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat

"Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid?"

No.  If you have enough solar resource and a large enough battery, any amount of extra loads can be supported off grid.  But it's much more efficient to use efficient electric appliances.  With today's available technology, anything that heats with resistance can be replaced with something better, and minimize the need for a huge battery and solar array to charge it.

I've had a remote Alaska off-grid facility for 27 years and consider resistive loads too demanding and inappropriate. I heat with wood when needed (only on site for March and summer) and have a supplementary propane space heater that is minimally operated. I have a 48v/1200 ah battery bank (16-600ah Sureties) and not had a need since 2014 to run any back up genset to charge the batteries. Each battery cycle rarely hits 25-30% drawdown. Avoid drawn down of 50% or more.  We have two 10 module azimuth tracing arrays for a total of 4.4kW. The trackers are not activated in March. Ample sun/diffused sun and albedo from the snowpack is ample for any electronics, shop equipment and kitchen appliances, LED lighting. 

I just finished reading the book "Photovoltaic Design and Installation for Dummies" by Ryan Mayfield. Overall, it seems like a good book. I noticed a surprising paragraph in it. 

"One type of load that should never be placed on a battery bank is anything that uses electricity to generate heat (these are called resistive loads). That rules our water heating, space heating, and electric stoves (incandescent lights also fall into this category). In a stand-alone, battery-based system, petroleum-based fuels generally support resistive loads, with propane being one of the most common in off-grid applications. For people connected to the grid with a utility-interactive, battery-based system, these loads can still be present; you just can't back them up with the batteries."

Does this mean that anyone who has electric heating, incandescent lighting, electric stoves, or space heating has to have a generator run by propane or another petroleum fuel if they are off-grid? 

Thanks in advance for your answers to this question. 

Best regards,

Kat