Couple looking up at home

What type of homes are suitable for residential solar panels?

Generally speaking solar panels can only be installed on single family homes. Solar panels produce their most power (watts) output when they are installed on a tilted, south facing roof, that is unshaded.

However, they can be installed east or west with a reduction in output. If installed on a roof facing due west the reduction in output is around 13% (depending on the pitch of the west facing roof).

Often where there is not a south facing roof a house will have both east and west facing roof spaces. In this instance the preference is usually for the one that is orientated closest to south but with the introduction of time of use billing and late afternoon peak periods more people are now opting for the west to capture more power generation in the later afternoon. This is particularly the case in California where all residential customers will be on time of use billing plans from their utility by the end of 2019.

Can I still purchase solar panels for my home if my roof is partly shaded?

Shade will affect the number of kWh's (kilowatt hours) of electricity that solar panels installed on your home would produce.

Prior to 2011 it was the case that a small amount of shading would make solar panels not viable for a home. The reason for this is that solar panels are connected electrically in a series (often known as a string) and in this configuration the Amperage that can come from each panel is only as much as the amps that flow through the panel with the lowest amount of current. So if one panel is shaded it would lower the output in each panel in the string. The inverters that were used in this instance are known as string inverters (click the following link for an explanation of the difference between string and micro-inverters).

However, since 2011 micro-inverters and panel level optimizers have become quite common through companies like Enphase and SolarEdge and have taken a significant portion of the market share ways from string-inverters.

Micro-inverters optimize the power at each panel level by varying current (I) and voltage (V) to maximize power output and then converting it to AC power at the panel. What this means is that a reduction in Amps in one panel caused by shade no longer affects the other panels that are not in shade.

Micro-inverters are slightly more expensive than regular string-inverters but can improve the results from a site with intermittent shade quite significantly.

Shading is one of those things that really requires an expert to determine how much it will affect the viability of solar panels on your home. The best way to get an expert to review the shading at your home is to enter your details on the Solar-Estimate marketplace. There is a section where you can enter information about your house, including roof type and roof shading, where you choose from a selection of shading examples that best describes your property. You can also select how many solar companies you would like to hear from, who will then provide you with their expert opinion on how much shading would reduce electricity production from solar panels on your home.

Can I install solar panels on my home if I rent?

Residential rental agreements are usually short term in nature and because solar is a long term project it is usually not possible for those renting to install it on the premises they rent.

However, legislators in some states have stepped in to provide a mechanism such that renters can get the same benefit from solar as a homeowner by installing solar panels in a community solar project.

The way community solar works is that you buy a small portion of the output of a large solar farm. These solar farms are usually 1-5 MW, or (1,000 to 5,000 kw ). You can buy a normal sized residential system from this community solar farm, say 5 kw and then you are credited with this percentage of the power generated at the community solar project.

Community solar is a great idea and to be frank I believe it is the way all distributed solar generation should have been done from the outset. Having said that, we all like to control what we own and so I think in my case that if I did own a house I would install my own solar panels rather than buy a system in a community solar farm.

There are now active community solar projects being sold in California, New York and Vermont, Colorado, Massachusetts and Texas. However, for most people that do own a house with a suitable roof most would rather install their panels on their own roof.

How many square feet of roof space are needed to install solar panels?

Close up installed solar panels

The square feet of suitable roof space you need to install solar panels square feet of suitable roof space you need to install solar panels will vary with the size of solar system you need. This in turn will vary with the amount of power you consume and the utility company you are with. You can work out how many solar panels you need for your home using this free solar panel calculator.

Generally speaking the average residential solar system is around 6kw and depending on the exact brand of solar panels you purchase this will require around 400 square feet of roof space. This roof space needs to ideally be orientated as close as possible to south facing and have a roof slope of between 18 and 30 degrees.

How much electricity will solar panels installed on my home produce?

The amount of energy that will be produced by a solar power system installed on your home will be affected by the location as well as the factors above. For calculations of solar energy output for a specific location visit Solar-Estimate.org.